Clinical Approach to Abdominal Pain

Pediatric Comprehensive Framework

1
Symptom Overview
Overview
2
Pathophysiology
Mechanism
3
History Taking
History
4
Physical Examination
Examination
5
Differential Diagnosis
Differential
6
Investigations
Workup
7
Clinical Decision-Making
Algorithm
8
Pearls and Pitfalls
Summary

1. Symptom Overview

Understanding the clinical significance and classification of pediatric abdominal pain

Abdominal pain is one of the most common presenting complaints in pediatric medicine, accounting for approximately 5-10% of all pediatric emergency department visits. It is the most frequent cause of gastroenterology referrals in children, with functional abdominal pain disorders affecting 10-25% of school-aged children worldwide. The challenge in pediatric abdominal pain lies in the wide spectrum of etiologies — ranging from benign, self-limiting conditions to life-threatening surgical emergencies — and the difficulty in obtaining accurate histories from young children.

Key Epidemiology

Emergency visits: Abdominal pain accounts for 5-10% of pediatric emergency department visits
Functional pain: 10-25% of school-aged children experience functional abdominal pain
Appendicitis: Lifetime risk of approximately 7-8%, with peak incidence at ages 10-19 years
Surgical causes: Only 1-8% of children with acute abdominal pain require surgical intervention
Recurrent pain: Affects approximately 10-15% of children aged 4-16 years

Definition

Abdominal pain in children refers to the subjective sensation of discomfort or distress localized to the abdomen, arising from stimulation of visceral, parietal, or referred pain pathways. It encompasses a broad spectrum from acute surgical emergencies to chronic functional disorders, and its presentation varies significantly with age due to developmental differences in anatomy, physiology, and communication abilities.

Classification by Duration

Category	Duration	Common Causes	Clinical Significance
Acute	Less than 1 week	Gastroenteritis, constipation, appendicitis, urinary tract infection, viral illness	Requires exclusion of surgical emergencies; most cases are self-limiting
Subacute	1 to 4 weeks	Prolonged infection, inflammatory conditions, constipation, early inflammatory bowel disease	May indicate evolving pathology; warrants closer monitoring
Chronic or Recurrent	Greater than 4 weeks or ≥3 episodes in 3 months	Functional abdominal pain disorders, inflammatory bowel disease, celiac disease, chronic constipation	Functional causes predominate; organic disease must be excluded

Classification by Character and Location

Visceral Pain

Character: Dull, poorly localized, crampy, intermittent

Location: Typically midline — epigastric, periumbilical, or suprapubic depending on embryological origin

Mechanism: Distension, ischemia, or inflammation of hollow viscera

Examples: Early appendicitis, gastroenteritis, intestinal obstruction, functional pain

Parietal (Somatic) Pain

Character: Sharp, well-localized, constant, aggravated by movement

Location: Localized to the area of peritoneal irritation

Mechanism: Inflammation of the parietal peritoneum

Examples: Late appendicitis with peritonitis, perforated viscus, peritoneal abscess

Classification by Location

Location	Common Causes by Age	Key Considerations
Periumbilical	Functional pain, early appendicitis, gastroenteritis, mesenteric lymphadenitis	Most common location for functional pain; visceral pain from midgut structures
Right Lower Quadrant	Appendicitis, mesenteric lymphadenitis, ovarian pathology (females), inguinal hernia	Appendicitis is the most common surgical emergency; consider ovarian torsion in females
Left Lower Quadrant	Constipation, ovarian pathology, inguinal hernia, testicular torsion (referred)	Constipation is extremely common; consider gynecological causes in adolescent females
Epigastric	Gastritis, peptic ulcer disease, pancreatitis, functional dyspepsia	Foregut visceral pain; Helicobacter pylori less common in children than adults
Right Upper Quadrant	Hepatitis, cholecystitis (rare), pneumonia with referred pain, Fitz-Hugh-Curtis syndrome	Consider hepatobiliary and pulmonary causes; gallstones increasing with obesity
Diffuse	Gastroenteritis, constipation, diabetic ketoacidosis, peritonitis, functional pain	Peritonitis causes severe diffuse tenderness with guarding; metabolic causes often overlooked

Age-Specific Considerations

Age Group	Unique Causes to Consider	Clinical Challenges
Neonates (0-28 days)	Necrotizing enterocolitis, malrotation with volvulus, Hirschsprung disease, incarcerated hernia, intestinal atresia	Cannot verbalize; abdominal distension and feeding intolerance are key signs; high index of suspicion for surgical emergencies
Infants (1-12 months)	Intussusception, incarcerated hernia, colic, cow’s milk protein allergy, pyloric stenosis (early infancy)	Inconsolable crying may be only sign; intussusception presents with classic triad in only 20-40% of cases
Toddlers (1-3 years)	Intussusception, constipation, gastroenteritis, urinary tract infection, foreign body ingestion	Limited verbal skills; may localize pain poorly; behavior changes important
School-age (4-12 years)	Functional abdominal pain, appendicitis, constipation, streptococcal pharyngitis with abdominal pain, inflammatory bowel disease	Can describe pain but may exaggerate or minimize; school avoidance may be factor
Adolescents (13-18 years)	Appendicitis, ovarian pathology, testicular torsion, inflammatory bowel disease, peptic ulcer disease, pregnancy-related	Consider pregnancy in all females; psychological factors common; sexually transmitted infections possible

Classification by Pattern and Timing

Pattern	Description	Suggests
Colicky (Intermittent)	Waves of severe pain with pain-free intervals; child may draw up legs	Intestinal obstruction, intussusception, renal colic, biliary colic
Constant and Progressive	Steady pain that worsens over hours; child lies still	Appendicitis, peritonitis, pancreatitis, pyelonephritis
Post-prandial	Pain occurring 30-60 minutes after meals	Peptic ulcer disease, functional dyspepsia, mesenteric ischemia (rare), biliary disease
Nocturnal	Pain that wakes the child from sleep	Organic pathology more likely; inflammatory bowel disease, peptic ulcer disease
School-related	Pain occurring on school days, improving on weekends and holidays	Functional abdominal pain with psychosocial component; still requires organic workup
Menstrual-related	Cyclical pain in adolescent females	Dysmenorrhea, endometriosis, mittelschmerz, ovarian cysts

Key Concept — The Pediatric Triad of Serious Abdominal Pain:

Appendicitis: The most common surgical emergency in children — classic migration from periumbilical to right lower quadrant pain occurs in only 50-60% of cases
Intussusception: Peak incidence at 5-9 months — the classic triad (colicky pain, “currant jelly” stool, palpable mass) is present in only 20-40% of cases
Malrotation with volvulus: A true neonatal emergency — bilious vomiting in a neonate is volvulus until proven otherwise

Clinical Pearl: Functional Abdominal Pain Disorders

Functional abdominal pain disorders (previously called “recurrent abdominal pain of childhood”) are the most common cause of chronic abdominal pain in children, affecting 10-25% of school-aged children. According to the Rome IV criteria, these are diagnosed based on characteristic symptom patterns after appropriate exclusion of organic disease — NOT as a diagnosis of exclusion. The four main subtypes are: functional dyspepsia, irritable bowel syndrome, abdominal migraine, and functional abdominal pain not otherwise specified.

2. Pathophysiology and Mechanisms

Understanding the underlying mechanisms of pediatric abdominal pain

Understanding the neuroanatomy and pathophysiology of abdominal pain is essential for accurate localization and diagnosis. Abdominal pain arises through three distinct pathways — visceral, parietal, and referred — each with characteristic features that provide important diagnostic clues. In children, developmental differences in nervous system maturation affect pain perception and localization, particularly in younger age groups.

The Three Pain Pathways

Pathway	Origin	Nerve Fibers	Characteristics	Clinical Examples
Visceral Pain	Abdominal organs and visceral peritoneum	Unmyelinated C fibers traveling with autonomic nerves	Dull, crampy, poorly localized, midline; often associated with autonomic symptoms (nausea, diaphoresis)	Early appendicitis, intestinal distension, biliary colic
Parietal (Somatic) Pain	Parietal peritoneum, abdominal wall, diaphragm	Myelinated A-delta fibers via spinal nerves	Sharp, well-localized, constant, worsened by movement or coughing	Peritonitis, appendicitis with rupture
Referred Pain	Distant sites sharing spinal cord segments with abdominal structures	Convergence of visceral and somatic afferents at spinal cord	Perceived at a site distant from the pathology; well-localized	Shoulder pain from diaphragm irritation, testicular pain from ureteral colic

Embryological Basis of Visceral Pain Localization

The location of visceral pain depends on the embryological origin of the affected organ. Understanding this relationship helps explain why early appendicitis causes periumbilical pain rather than right lower quadrant pain.

Embryological Division	Structures	Spinal Segments	Pain Location
Foregut	Esophagus, stomach, duodenum (proximal to ampulla), liver, biliary tree, pancreas, spleen	T5-T9	Epigastric region
Midgut	Duodenum (distal to ampulla), jejunum, ileum, appendix, cecum, ascending colon, proximal transverse colon	T8-T11	Periumbilical region
Hindgut	Distal transverse colon, descending colon, sigmoid colon, rectum, upper anal canal	T11-L1	Suprapubic and hypogastric region

Clinical Pearl: The Classic Migration of Appendicitis Pain

Early appendicitis causes visceral pain (via midgut afferents) perceived as vague periumbilical discomfort. As inflammation progresses and involves the parietal peritoneum, the pain “migrates” and becomes sharp and localized to the right lower quadrant. This classic migration occurs in only 50-60% of pediatric appendicitis cases — atypical presentations are common, especially in younger children and those with retrocecal or pelvic appendices.

Stimuli That Cause Abdominal Pain

Mechanical Stimuli

Distension: Stretching of hollow viscus walls activates mechanoreceptors (intestinal obstruction, constipation, intussusception)

Traction: Pulling on mesentery or capsule (hepatomegaly, splenomegaly, ovarian torsion)

Contraction: Strong smooth muscle contractions against resistance (biliary colic, ureteral colic)

Inflammatory Stimuli

Chemical mediators: Prostaglandins, bradykinin, histamine, and cytokines sensitize nociceptors

Bacterial toxins: Direct mucosal irritation and inflammatory cascade activation

Autoimmune: Inflammatory bowel disease, vasculitis

Ischemic Stimuli

Mechanism: Tissue hypoxia leads to accumulation of metabolic byproducts and inflammatory mediators

Examples: Volvulus, incarcerated hernia, testicular torsion, ovarian torsion, mesenteric ischemia

Character: Often severe, constant, out of proportion to examination findings

Common Referred Pain Patterns in Children

Pathology	Referred Pain Location	Explanation
Diaphragmatic irritation	Shoulder tip (Kehr’s sign)	Phrenic nerve (C3-C5) shares segments with shoulder dermatomes
Lower lobe pneumonia	Upper abdominal pain	Diaphragmatic irritation from adjacent lung pathology
Ureteral colic	Groin, testicle, or labia	Genitofemoral nerve (L1-L2) shares segments with ureter
Testicular torsion	Lower abdominal pain	Testicle shares embryological origin and innervation with abdominal structures
Hip pathology	Knee pain, groin pain	Obturator nerve (L2-L4) innervates both hip and knee

Critical Concept: Extra-Abdominal Causes of Abdominal Pain

Always consider extra-abdominal causes of abdominal pain in children:

Pulmonary: Lower lobe pneumonia, pleuritis — especially in children with fever and abdominal pain
Cardiac: Myocarditis, pericarditis — rare but important in children with chest pain and abdominal discomfort
Testicular: Testicular torsion — ALWAYS examine the genitalia in boys with abdominal pain
Pharyngeal: Streptococcal pharyngitis — commonly causes abdominal pain with mesenteric lymphadenitis
Metabolic: Diabetic ketoacidosis — abdominal pain is a presenting feature in up to 50% of new-onset cases

Mechanism by Condition

Condition	Primary Mechanism	Pain Characteristics	Why Understanding This Matters
Appendicitis	Luminal obstruction → distension → ischemia → inflammation → peritonitis	Visceral (periumbilical) → Parietal (right lower quadrant) over 12-24 hours	Explains classic pain migration; perforation more common in younger children due to thinner wall and delayed diagnosis
Intussusception	Bowel telescoping → mesenteric traction → venous congestion → ischemia	Severe colicky pain with pain-free intervals; child draws up legs	Intermittent obstruction causes intermittent pain; ischemia causes lethargy between episodes
Malrotation with volvulus	Midgut twisting → mesenteric vessel occlusion → rapid bowel ischemia and necrosis	Sudden onset, severe, constant pain with bilious vomiting	Time-critical diagnosis; complete vascular compromise leads to short gut syndrome or death
Constipation	Fecal impaction → colonic distension → visceral pain; hard stool passage → anal fissure pain	Crampy, intermittent, often left lower quadrant or suprapubic	Most common cause of chronic abdominal pain; palpable fecal masses on examination
Gastroenteritis	Mucosal inflammation → prostaglandin release → increased motility → cramping	Diffuse, crampy, associated with diarrhea and vomiting	Pain typically precedes diarrhea; viral more common than bacterial
Mesenteric lymphadenitis	Lymph node inflammation (often viral) → capsular distension → visceral pain	Right lower quadrant pain mimicking appendicitis; often with upper respiratory symptoms	Common appendicitis mimic; diagnosis of exclusion; usually self-limiting
Functional abdominal pain	Visceral hypersensitivity + altered gut-brain axis + psychosocial factors	Periumbilical, non-specific; does not wake child from sleep; no associated red flags	Real pain with real impact; not “making it up”; biopsychosocial approach to treatment
Ovarian torsion	Adnexal twisting → venous then arterial occlusion → ischemia	Sudden onset, severe, unilateral lower quadrant pain; may be intermittent	Ovary can intermittently torse and detorse; pain may wax and wane
Testicular torsion	Spermatic cord twisting → venous then arterial compromise → ischemia	Severe testicular pain often with referred lower abdominal pain	6-hour window for salvage; abdominal pain may be only complaint in young children

Developmental Considerations in Pediatric Pain

Why Pain Localization is Poor in Young Children

Immature nervous system: Myelination incomplete until age 2-3 years, affecting pain localization
Limited verbal ability: Cannot describe location, character, or severity accurately
Cognitive development: Cannot understand concept of localization until around age 7-8 years
Fear and anxiety: May report diffuse pain due to fear of examination

Clinical Implications

Neonates and infants express pain through crying, irritability, and changes in feeding
Toddlers may point to umbilicus regardless of pain location
Serial examinations are crucial — pathology often declares itself over time
Parental observation of behavior changes is more reliable than child’s localization in young children

Pathophysiology of Intestinal Obstruction

Intestinal obstruction is a critical concept in pediatric abdominal pain, as several emergencies present with obstructive features. Understanding the pathophysiology explains the clinical progression.

Stage	Pathophysiology	Clinical Features
Early Obstruction	Increased peristalsis against obstruction; fluid and gas accumulation proximal to obstruction	Colicky pain, vomiting (bilious if distal to ampulla), hyperactive bowel sounds
Progressive Obstruction	Bowel distension; third-spacing of fluid into bowel lumen and wall	Abdominal distension, dehydration, electrolyte abnormalities
Late/Complicated Obstruction	Venous congestion → arterial compromise → ischemia → necrosis → perforation	Constant severe pain, peritonitis, shock, absent bowel sounds

Often Overlooked: The Gut-Brain Axis in Functional Pain

Functional abdominal pain disorders are now understood to result from dysregulation of the gut-brain axis — a bidirectional communication system involving neural, hormonal, and immunological pathways. Children with functional pain have demonstrated visceral hypersensitivity (lower pain thresholds to balloon distension), altered intestinal motility, and changes in gut microbiome composition. Psychological stress activates the hypothalamic-pituitary-adrenal axis, increasing intestinal permeability and visceral sensitivity. This explains why cognitive-behavioral therapy and gut-directed hypnotherapy are effective treatments — they modulate the gut-brain axis.

Complications of Abdominal Pain Conditions

Condition	Complication	Mechanism	Prevention
Appendicitis	Perforation, abscess, peritonitis	Delayed diagnosis → ischemia → necrosis → rupture	Early recognition; perforation rate higher in children under 5 years (up to 80%)
Intussusception	Bowel necrosis, perforation	Prolonged venous and arterial compromise	Early reduction; surgical intervention if prolonged or failed reduction
Volvulus	Short bowel syndrome, death	Rapid complete mesenteric vessel occlusion	Emergency surgical intervention; high index of suspicion in neonates
Ovarian torsion	Ovarian loss, infertility	Prolonged ischemia → necrosis	Early surgical detorsion; ovary often salvageable even if appears necrotic
Testicular torsion	Testicular loss	Ischemia beyond 6-8 hours	Salvage rate 90% at 6 hours; drops to 10% at 24 hours

3. History Taking

A comprehensive approach to eliciting the pediatric abdominal pain history

Red Flags — Require Urgent Evaluation

Bilious (green) vomiting — Malrotation with volvulus until proven otherwise
Bloody stool or “currant jelly” stool — Intussusception, ischemic bowel
Abdominal distension with vomiting — Intestinal obstruction
Severe localized tenderness — Peritonitis, appendicitis
Pain out of proportion to examination — Mesenteric ischemia, volvulus
Involuntary guarding or rigidity — Peritonitis

Signs of shock — Tachycardia, poor perfusion, altered mental status
Testicular pain or swelling — Testicular torsion (6-hour window)
Inconsolable infant — Serious pathology; intussusception, incarcerated hernia
Pain waking child from sleep — Organic pathology more likely
Weight loss or growth failure — Inflammatory bowel disease, malignancy, celiac disease
Fever with localized abdominal pain — Appendicitis, abscess, pyelonephritis

Age-Specific Red Flags

Age Group	Critical Red Flags	Must Consider
Neonates (0-28 days)	Bilious vomiting, abdominal distension, failure to pass meconium, bloody stool	Malrotation with volvulus, necrotizing enterocolitis, Hirschsprung disease, intestinal atresia
Infants (1-12 months)	Inconsolable crying, drawing up legs, lethargy between pain episodes, palpable mass	Intussusception, incarcerated hernia, volvulus
Toddlers and School-age	Pain migration to right lower quadrant, fever with localized tenderness, limping or hip pain	Appendicitis, septic hip, psoas abscess
Adolescents	Sexually active female with abdominal pain, missed period, vaginal discharge	Ectopic pregnancy, pelvic inflammatory disease, ovarian torsion

Systematic History: The “ABDOMEN” Approach

Use the mnemonic “ABDOMEN” to ensure comprehensive history taking in pediatric abdominal pain:

A — Attributes of Pain: Location, character, severity, radiation, timing, duration, progression
B — Bowel and Bladder: Stool pattern, constipation, diarrhea, blood in stool, urinary symptoms
D — Diet and Development: Oral intake, feeding history, growth pattern, developmental milestones
O — Other Symptoms: Fever, vomiting (bilious?), rash, joint pain, respiratory symptoms
M — Medications and Medical History: Current medications, allergies, past medical and surgical history
E — Events and Exposures: Recent illness, sick contacts, travel, trauma, ingestions
N — Neonatal and Family History: Birth history, family history of gastrointestinal disease, psychosocial factors

A — Attributes of Pain

Attribute	Key Questions	Clinical Significance
Location	“Point with one finger to where it hurts the most.” “Did the pain start somewhere else and move?”	Periumbilical → right lower quadrant migration suggests appendicitis; children under 7 often point to umbilicus regardless of location
Character	“Is it sharp like a knife or dull and achy?” “Does it come and go or is it there all the time?”	Colicky = obstruction, intussusception; constant = peritonitis, appendicitis; crampy = gastroenteritis
Severity	Use age-appropriate pain scales (FLACC for young children, Wong-Baker faces, numeric scale for older children)	Severe pain with minimal findings = concerning for ischemia; pain out of proportion to examination is a red flag
Timing	“When did it start? What were you doing?” “Does it happen at certain times of day?”	Sudden onset = volvulus, torsion, perforation; gradual = appendicitis, infection; school-day pattern = functional
Radiation	“Does the pain go anywhere else?” “Do you feel it in your back or shoulder?”	Back radiation = pancreatitis, pyelonephritis; shoulder = diaphragm irritation; groin = ureteral colic, hernia
Aggravating/Relieving	“What makes it better or worse?” “Does eating, moving, or lying still change it?”	Worse with movement = peritonitis; better with defecation = constipation; worse after meals = peptic disease

Targeted Questions by Suspected Cause

Suspected Cause	Key Features	Ask This Question
Appendicitis	Pain migration, anorexia, fever, right lower quadrant tenderness	“Did the pain start around the belly button and then move to the right side?” “Has your child wanted to eat anything today?”
Intussusception	Colicky pain, drawing up legs, lethargy between episodes, bloody stool	“Does the pain come in waves with periods where your child seems better?” “Have you noticed any blood or mucus in the diaper?”
Malrotation with volvulus	Bilious vomiting, acute onset, sick appearance	“What color is the vomit — is it green or yellow-green?” “How quickly did your baby become this sick?”
Constipation	Infrequent hard stools, straining, withholding behavior	“How often does your child have a bowel movement? What do the stools look like?” “Does your child hold in their stool or hide when having a bowel movement?”
Gastroenteritis	Vomiting, diarrhea, sick contacts, crampy pain	“Is anyone else at home or school sick?” “Did the vomiting or diarrhea start before, after, or with the pain?”
Urinary tract infection	Dysuria, frequency, urgency, fever, flank pain	“Does it hurt when your child urinates?” “Have you noticed any changes in the smell or color of the urine?”
Testicular torsion	Sudden testicular pain, nausea, abdominal pain	“Does your son have any pain in his testicles or groin?” (Ask directly — children may not volunteer this)
Ovarian torsion	Sudden unilateral lower quadrant pain, nausea, intermittent pain	“Did the pain start suddenly?” “Does it come and go, or has it been getting steadily worse?”
Inflammatory bowel disease	Chronic diarrhea, blood in stool, weight loss, growth failure, extraintestinal manifestations	“Has your child lost weight or stopped growing as expected?” “Have you noticed blood in the stool or joint pains?”
Functional abdominal pain	Periumbilical pain, no red flags, normal growth, school-related pattern	“Does the pain ever wake your child from sleep?” “Is the pain worse on school days?” “Are there any stressors at home or school?”
Diabetic ketoacidosis	Polyuria, polydipsia, weight loss, fruity breath	“Has your child been drinking more than usual or urinating more frequently?” “Have they lost weight recently?”
Pregnancy-related (adolescents)	Missed period, sexually active, vaginal bleeding	“When was your last menstrual period?” “Is there any chance you could be pregnant?” (Ask confidentially without parents present)

B — Bowel and Bladder Function

Bowel History

Stool frequency: Normal ranges from 3 times daily to once every 3 days
Stool consistency: Use Bristol Stool Chart — Type 1-2 suggests constipation, Type 6-7 suggests diarrhea
Blood in stool: Bright red (lower gastrointestinal), dark/tarry (upper gastrointestinal), “currant jelly” (intussusception)
Mucus: May indicate infection, inflammatory bowel disease, or intussusception
Stool withholding: Crossing legs, hiding — suggests constipation with behavioral component
Soiling/encopresis: Overflow incontinence from fecal impaction

Urinary History

Dysuria: Burning or pain with urination — urinary tract infection
Frequency/urgency: Increased voiding — urinary tract infection, diabetes
Hematuria: Blood in urine — urinary tract infection, stones, glomerulonephritis
Urine color/odor: Dark concentrated = dehydration; foul-smelling = infection
Polyuria with polydipsia: Consider diabetes mellitus
Difficulty voiding: Consider obstruction, neurological causes

D — Diet and Development

Dietary History

Current oral intake: Anorexia is common in appendicitis; continued appetite makes serious pathology less likely
Recent dietary changes: New foods, lactose intolerance symptoms
Fluid intake: Assess hydration status
Feeding difficulties: Choking, gagging, refusal — may suggest reflux or anatomical issues in infants
Relationship to meals: Post-prandial pain suggests peptic disease, biliary pathology

Growth and Development

Growth parameters: Plot on growth chart — failure to thrive is a red flag
Weight trajectory: Weight loss suggests inflammatory bowel disease, celiac disease, malignancy
Pubertal development: Delayed puberty may accompany inflammatory bowel disease
Developmental milestones: Relevant for neurological causes of constipation

O — Other Associated Symptoms

Associated Symptom	Key Questions	Suggests
Vomiting	Bilious (green)? Bloody? Projectile? Timing relative to pain?	Bilious = obstruction distal to ampulla; bloody = upper gastrointestinal bleeding; before pain = gastroenteritis; after pain = appendicitis
Fever	Height, duration, pattern, response to antipyretics	High fever with localized pain = appendicitis, abscess; low-grade = mesenteric lymphadenitis, viral
Rash	Type, distribution, timing relative to pain	Purpuric rash on legs/buttocks = Henoch-Schönlein purpura
Joint pain	Which joints? Swelling? Migration?	Inflammatory bowel disease, Henoch-Schönlein purpura, reactive arthritis
Respiratory symptoms	Cough, sore throat, runny nose	Lower lobe pneumonia causing referred abdominal pain; streptococcal pharyngitis with mesenteric lymphadenitis
Lethargy	Altered mental status between pain episodes?	Intussusception — lethargy between episodes is characteristic and concerning
Headache	Timing, severity, associated symptoms	Abdominal migraine (episodic midline pain with pallor, anorexia, nausea, vomiting)

M — Medications and Medical History

Medications That May Cause Abdominal Pain

Non-steroidal anti-inflammatory drugs: Gastritis, peptic ulcer disease
Antibiotics: Antibiotic-associated diarrhea, Clostridioides difficile colitis
Corticosteroids: Peptic ulcer disease, pancreatitis
Iron supplements: Constipation, gastric irritation
Opioids: Constipation
Chemotherapy: Mucositis, typhlitis
Valproic acid: Pancreatitis

Relevant Past Medical History

Previous abdominal surgery: Adhesive obstruction risk
Sickle cell disease: Vaso-occlusive crisis, gallstones, splenic sequestration
Cystic fibrosis: Distal intestinal obstruction syndrome, pancreatitis
Immunocompromised: Typhlitis, opportunistic infections
Congenital heart disease: Mesenteric ischemia
Known ovarian cysts: Torsion risk
Previous intussusception: Recurrence rate 5-10%

E — Events and Exposures

Exposure	Ask About	Consider
Recent illness	Upper respiratory infection, gastroenteritis in past 2-4 weeks	Mesenteric lymphadenitis, post-infectious irritable bowel syndrome, intussusception (often follows viral illness)
Sick contacts	Family members, daycare, school outbreaks	Gastroenteritis, streptococcal pharyngitis
Travel	Recent travel, especially to endemic areas	Parasitic infections (Giardia), traveler’s diarrhea, hepatitis A
Trauma	Falls, sports injuries, bicycle handlebar injuries	Solid organ injury (spleen, liver), pancreatic injury, duodenal hematoma
Foreign body ingestion	Button batteries, magnets, coins, sharp objects	Esophageal or gastric perforation, obstruction, heavy metal toxicity
Toxic ingestions	Access to medications, household chemicals	Iron toxicity, lead poisoning, caustic ingestion

N — Neonatal, Family, and Psychosocial History

Birth and Neonatal History

Gestational age: Prematurity increases risk of necrotizing enterocolitis history, inguinal hernia
Birth weight: Intrauterine growth restriction may indicate underlying conditions
Neonatal complications: Necrotizing enterocolitis, bowel surgery → adhesions, short gut
Meconium passage: Delayed passage suggests Hirschsprung disease
Neonatal jaundice: Biliary atresia if prolonged conjugated hyperbilirubinemia

Family History

Inflammatory bowel disease: 10-25% of patients have affected first-degree relative
Celiac disease: Strong genetic component
Peptic ulcer disease: Helicobacter pylori clusters in families
Familial Mediterranean fever: Recurrent episodes of fever and serositis
Hereditary pancreatitis: Recurrent pancreatitis episodes
Hirschsprung disease: Increased risk in siblings
Functional gastrointestinal disorders: Often cluster in families

Psychosocial Assessment — Essential for Functional Pain

Psychosocial factors play a significant role in functional abdominal pain disorders and should be assessed sensitively:

School performance: Academic difficulties, bullying, school avoidance
Family stressors: Parental conflict, divorce, illness, death, new sibling
Social relationships: Peer relationships, social isolation
Mental health: Anxiety, depression (common comorbidities)
History of abuse: Physical, emotional, or sexual abuse may present with somatic complaints
Secondary gain: Attention, avoidance of school or activities

Important: Identifying psychosocial factors does NOT mean the pain is “not real.” Functional pain causes real suffering and requires appropriate treatment.

Clinical Pearl: History Taking in Different Age Groups

Age Group	History Source	Key Approach
Infants	Entirely from caregivers	Focus on behavior changes: crying pattern, feeding, activity, stool pattern. Ask about inconsolable crying, drawing up legs.
Toddlers (1-3 years)	Primarily caregivers with limited child input	Children may point to pain but localization unreliable. Observe behavior during history-taking.
Preschool (3-5 years)	Combined caregiver and child	Use simple questions. Children may exaggerate or minimize. “Show me on your tummy where it hurts.”
School-age (6-12 years)	Child with caregiver supplementation	Can describe pain character and timing. May be influenced by parental anxiety. Take history from child first.
Adolescents	Primarily from patient	Interview adolescent alone for sensitive topics (sexual activity, substance use, mental health). Confidentiality is important.

4. Physical Examination

A systematic head-to-toe approach for pediatric abdominal pain

Systematic Framework: Use the “General to Specific” approach for complete examination of children presenting with abdominal pain. Begin with observation before touching the child, and save the most painful area for last. In young or anxious children, examine while on caregiver’s lap and use distraction techniques.

General Inspection — Before Touching the Child

Observation	What to Look For	Clinical Significance
Level of distress	Crying, facial grimacing, body position, interaction with environment	Inconsolable = concerning; playful and interactive = less likely serious pathology
Position	Lying still vs. writhing; knees drawn up; leaning forward	Lying still = peritonitis; writhing = colicky pain (renal, biliary, intestinal); knees drawn up = peritoneal irritation
Movement	Willingness to walk, jump, climb onto examination table	Child who walks comfortably and climbs onto table is less likely to have peritonitis
Color	Pallor, jaundice, cyanosis, flushing	Pallor = anemia, shock, intussusception; jaundice = hepatobiliary disease, hemolysis
Nutritional status	Wasting, obesity, edema	Cachexia = chronic disease, malignancy, inflammatory bowel disease; obesity = increased gallstone risk
Hydration	Mucous membranes, skin turgor, tears, fontanelle (infants)	Dehydration common with vomiting and diarrhea; sunken fontanelle in infants

Vital Signs — Age-Appropriate Normal Values

Age Group	Heart Rate (bpm)	Respiratory Rate (/min)	Systolic Blood Pressure (mmHg)	Temperature
Neonate (0-28 days)	100-160	30-60	60-90	36.5-37.5°C
Infant (1-12 months)	100-150	25-40	80-100	36.5-37.5°C
Toddler (1-3 years)	90-140	20-30	90-105	36.5-37.5°C
Preschool (3-5 years)	80-120	20-25	95-105	36.5-37.5°C
School-age (6-12 years)	70-110	18-22	100-115	36.5-37.5°C
Adolescent (13-18 years)	60-100	12-20	110-130	36.5-37.5°C

Vital Sign Red Flags

Tachycardia out of proportion to fever: Consider shock, dehydration, pain, anemia
Hypotension: Late sign of shock in children — do not wait for hypotension to recognize serious illness
Tachypnea with abdominal pain: Consider pneumonia, metabolic acidosis (diabetic ketoacidosis), compensation for shock
High fever (>39°C) with localized abdominal pain: Consider appendicitis with perforation, abscess, pyelonephritis

Growth Parameters

Plot weight, height, and head circumference (for children under 3 years) on appropriate growth charts. Compare to previous measurements if available.

Red Flags

Weight loss or failure to gain weight
Crossing percentile lines downward
Height velocity declining
Delayed puberty with chronic symptoms

Suggests

Inflammatory bowel disease
Celiac disease
Malignancy
Chronic infection

Head, Eyes, Ears, Nose, and Throat Examination

Mouth and Throat

Pharyngitis: Streptococcal pharyngitis commonly causes abdominal pain in children via mesenteric lymphadenitis
Aphthous ulcers: May indicate inflammatory bowel disease (Crohn disease)
Dry mucous membranes: Dehydration
Dental caries: May cause referred abdominal pain

Eyes

Jaundice (scleral icterus): Hepatobiliary disease, hemolysis
Conjunctival pallor: Anemia — consider gastrointestinal bleeding
Kayser-Fleischer rings: Wilson disease (rare)
Uveitis: Inflammatory bowel disease, juvenile idiopathic arthritis

Chest Examination

Don’t Forget the Lungs!

Lower lobe pneumonia is an important cause of abdominal pain in children due to diaphragmatic irritation. Always auscultate the lung bases in children presenting with abdominal pain, especially those with fever or respiratory symptoms.

Inspection: Respiratory effort, accessory muscle use, chest asymmetry
Auscultation: Decreased breath sounds, crackles, or bronchial breathing at lung bases suggests pneumonia
Percussion: Dullness over lung bases

Abdominal Examination — The Core Assessment

Inspection

Finding	Description	Clinical Significance
Distension	Generalized abdominal enlargement; may be symmetric or asymmetric	Obstruction, ascites, organomegaly, mass; always concerning in neonates
Visible peristalsis	Waves of movement across abdomen	Intestinal obstruction; classically seen in pyloric stenosis (left to right waves)
Scars	Previous surgical incisions	Adhesive obstruction risk; inquire about previous surgeries
Hernias	Bulges at umbilicus, inguinal region, or incision sites	Incarcerated hernia — check for reducibility
Skin changes	Ecchymosis, erythema, rash	Cullen sign (periumbilical bruising) or Grey Turner sign (flank bruising) = hemorrhagic pancreatitis (rare in children)
Abdominal wall movement	Movement with respiration	Reduced movement = peritonitis (child splints to minimize pain)

Auscultation (Before Palpation)

Finding	Description	Suggests
Normal bowel sounds	Intermittent gurgling, every 5-15 seconds	Normal intestinal motility
Hyperactive bowel sounds	Frequent, high-pitched, “tinkling”	Early obstruction, gastroenteritis, diarrhea
Absent bowel sounds	No sounds heard after listening for 2-3 minutes in each quadrant	Ileus, peritonitis, late obstruction
Bruits	Vascular sounds over aorta or renal arteries	Vascular abnormality (rare in children)

Palpation — Technique Tips for Children

Pediatric Palpation Pearls:

Warm your hands before touching
Start away from the area of maximal pain
Use distraction — have child blow on a pinwheel, count ceiling tiles, or talk about favorite activities
In anxious children, palpate through the caregiver’s hand first, then transition to your own
Use the child’s own hand placed under yours to begin palpation
Observe the child’s face, not the abdomen, while palpating
Bend the child’s knees to relax abdominal muscles
In infants, use a pacifier or feeding to facilitate examination

Finding	Technique	Clinical Significance
Tenderness	Light then deep palpation; note location and severity	Localized tenderness helps identify pathology; diffuse tenderness suggests peritonitis or functional pain
Guarding	Voluntary (relaxes with distraction) vs. involuntary (persists despite distraction)	Involuntary guarding = peritoneal irritation; voluntary guarding may be anxiety or functional
Rigidity	“Board-like” abdomen that does not relax	Peritonitis — surgical emergency
Rebound tenderness	Pain on sudden release of pressure (test gently or use percussion instead)	Peritoneal irritation; may be unreliable in young children — use cough test or “shake” test instead
Masses	Deep palpation; note location, size, mobility, tenderness	Right lower quadrant = appendiceal abscess; “sausage-shaped” right upper quadrant = intussusception; suprapubic = distended bladder, pregnancy
Hepatomegaly	Palpate from right lower quadrant upward; liver edge normally palpable 1-2 cm below costal margin in infants	Hepatitis, heart failure, metabolic disease, malignancy
Splenomegaly	Palpate from right lower quadrant toward left upper quadrant	Infection (mononucleosis), hematologic disease, portal hypertension
Fecal masses	Firm, mobile, indentable masses, often in left lower quadrant	Constipation — very common cause of chronic abdominal pain

Special Tests and Signs

Test/Sign	Technique	Positive Finding Indicates
McBurney’s point tenderness	Palpate at point one-third distance from anterior superior iliac spine to umbilicus	Appendicitis
Rovsing’s sign	Palpate left lower quadrant — pain felt in right lower quadrant	Appendicitis (referred peritoneal irritation)
Psoas sign	Pain with passive extension of right hip (patient on left side) or active flexion against resistance	Retrocecal appendicitis, psoas abscess
Obturator sign	Pain with passive internal rotation of flexed right hip	Pelvic appendicitis, pelvic abscess
Murphy’s sign	Arrest of inspiration during palpation of right upper quadrant	Cholecystitis (less common in children than adults)
Cough test	Ask child to cough — observe for pain localization	Peritoneal irritation (more reliable than rebound in children)
Jump/Hop test	Ask child to jump or hop on one foot	Child who can hop without pain is less likely to have peritonitis
Shake test	Gently shake the bed or stretcher	Pain indicates peritoneal irritation
Carnett’s sign	Palpate tender area while patient tenses abdominal muscles (head lift)	Pain increases = abdominal wall pathology; pain decreases = intra-abdominal pathology

Percussion

Tympany: Normal over bowel; increased with obstruction or distension
Dullness: Over solid organs (liver, spleen), full bladder, masses, or ascites
Shifting dullness: Suggests ascites
Percussion tenderness: Alternative to rebound testing — less distressing for children

Genitourinary Examination

Critical: Always Examine the Genitalia

Testicular torsion and incarcerated inguinal hernias are surgical emergencies that can present with abdominal pain alone. ALWAYS examine the external genitalia in children with abdominal pain, regardless of whether they report groin or testicular symptoms.

Males

Inspect: Penis, scrotum, inguinal region for swelling, erythema, hernias
Palpate testes: Both testes present, size, lie (horizontal lie suggests bell-clapper deformity)
Cremasteric reflex: Stroke inner thigh — testis should retract; absent in torsion
Inguinal canals: Palpate for hernias; have child cough or strain

Females

Inspect: External genitalia for discharge, lesions, signs of trauma
Vaginal discharge: May indicate infection or foreign body
Inguinal region: Check for hernias (less common than males)
Pelvic examination: Generally not performed in prepubertal children; indicated in sexually active adolescents with suspected pelvic pathology

Rectal Examination

Rectal examination is not routinely required in pediatric abdominal pain assessment. Consider in specific situations:

Indications: Suspected constipation with no response to treatment, gastrointestinal bleeding, suspected intussusception (may feel mass or “currant jelly” stool), suspected appendicitis with atypical presentation
Findings: Stool consistency and volume, masses, blood, tenderness
Note: May be deferred if diagnosis is clear from other findings; should be performed by experienced clinician with appropriate explanation and consent

Musculoskeletal Examination

Area	Examine For	Significance
Spine	Tenderness, deformity, midline defects	Vertebral osteomyelitis, discitis, spinal pathology causing referred pain
Hip	Range of motion, pain with movement	Septic hip, transient synovitis (referred pain to abdomen), psoas abscess
Costovertebral angle	Tenderness on percussion	Pyelonephritis
Joints	Swelling, erythema, tenderness	Henoch-Schönlein purpura, inflammatory bowel disease (arthritis), reactive arthritis

Skin Examination

Finding	Description	Associated Condition
Purpuric rash	Non-blanching purple spots, especially on legs and buttocks	Henoch-Schönlein purpura (may have abdominal pain before rash appears)
Erythema nodosum	Tender red nodules on shins	Inflammatory bowel disease, streptococcal infection
Jaundice	Yellow discoloration of skin	Hepatobiliary disease, hemolysis
Dermatitis herpetiformis	Intensely itchy vesicular rash on extensor surfaces	Celiac disease
Pyoderma gangrenosum	Painful ulcers with undermined edges	Inflammatory bowel disease
Acanthosis nigricans	Velvety hyperpigmentation in skin folds	Insulin resistance, obesity (associated with gallstones)

Expected Findings by Etiology

Condition	General Appearance	Abdominal Findings	Other Key Findings
Appendicitis	Ill-appearing, walks slowly, avoids movement	Right lower quadrant tenderness, guarding, positive psoas/obturator signs	Low-grade fever; may be normal early
Intussusception	Episodic distress alternating with lethargy; pallor	“Sausage-shaped” mass right upper quadrant; “Dance sign” (empty right lower quadrant)	Bloody stool on rectal examination
Malrotation with volvulus	Acutely ill, may be in shock	Distension, diffuse tenderness, may be non-specific early	Bilious vomiting; rapid deterioration
Constipation	Well-appearing	Palpable fecal masses, especially left lower quadrant; mild diffuse tenderness	May have fecal soiling; normal examination otherwise
Gastroenteritis	Variable; may show dehydration	Diffuse mild tenderness, hyperactive bowel sounds; no peritoneal signs	Fever, dehydration signs
Mesenteric lymphadenitis	Mildly ill; recent upper respiratory infection	Right lower quadrant tenderness (less localized than appendicitis)	Pharyngitis, cervical lymphadenopathy
Testicular torsion	Severe distress, nausea	May have lower abdominal tenderness	Swollen, high-riding testis; absent cremasteric reflex
Functional abdominal pain	Well-appearing; normal growth	Periumbilical tenderness without guarding; normal examination	No red flags; may have associated anxiety
Henoch-Schönlein purpura	Variable; may have arthritis, appears uncomfortable	Diffuse tenderness; may have guarding with severe intestinal involvement	Purpuric rash on buttocks and legs; joint swelling
Diabetic ketoacidosis	Ill, dehydrated, Kussmaul breathing	Diffuse tenderness, may mimic acute abdomen	Fruity breath, altered mental status, polyuria history

Important Teaching Point: Normal Examination is Common

Many significant conditions can present with minimal or normal physical examination findings, especially early in the disease course:

Early appendicitis: May have only vague periumbilical tenderness before localization
Intussusception: Between episodes, the child may appear completely well with a normal examination
Ovarian torsion: Intermittent torsion may cause minimal findings between episodes
Functional abdominal pain: By definition, examination is normal

Serial examinations are crucial — pathology often declares itself over time. A normal examination does not exclude serious disease, especially if the history is concerning.

5. Differential Diagnosis

Systematic approach organized by probability, age, and clinical features

The differential diagnosis of pediatric abdominal pain is broad and varies significantly with age. A systematic approach using probability-based thinking, combined with age-specific considerations, helps narrow the differential efficiently. Remember that only 1-8% of children presenting with acute abdominal pain require surgical intervention — but identifying these children is critical.

Acute Abdominal Pain (Duration: Less than 1 week)

Probability	Condition	Key Features	Red Flags
COMMON (~70-80%)	Viral gastroenteritis	Vomiting, diarrhea, diffuse crampy pain, sick contacts	Severe dehydration, bloody stool, bilious vomiting
	Constipation	Infrequent hard stools, left lower quadrant or suprapubic pain, palpable fecal masses	Failure to pass meconium (neonate), abdominal distension with vomiting
	Viral illness with abdominal pain	Upper respiratory symptoms, fever, generalized discomfort	Localized tenderness, peritoneal signs
	Mesenteric lymphadenitis	Right lower quadrant pain, recent upper respiratory infection, pharyngitis	Pain migration, involuntary guarding (suggests appendicitis instead)
	Urinary tract infection	Dysuria, frequency, fever, suprapubic or flank pain	High fever with flank pain (pyelonephritis)
LESS COMMON (~15-25%)	Appendicitis	Periumbilical pain migrating to right lower quadrant, anorexia, fever, vomiting after pain onset	Perforation signs: high fever, rigidity, ill appearance
	Streptococcal pharyngitis	Sore throat, fever, abdominal pain (mesenteric adenitis)	Scarlet fever rash, dehydration
	Pneumonia (lower lobe)	Cough, fever, tachypnea, upper abdominal pain	Respiratory distress, hypoxia
	Trauma	History of injury, localized tenderness, bruising	Signs of solid organ injury, hemodynamic instability
UNCOMMON BUT SERIOUS (~5-10%)	Intussusception	Colicky pain, drawing up legs, lethargy between episodes, age 3 months to 3 years	Bloody “currant jelly” stool, palpable mass, shock
	Malrotation with volvulus	Bilious vomiting, acute onset, neonates and young infants	Rapid deterioration, shock, abdominal distension
	Incarcerated inguinal hernia	Inguinal swelling, irritability, vomiting	Non-reducible, tender mass; signs of obstruction
	Testicular torsion	Sudden testicular or lower abdominal pain, nausea, swollen testicle	Absent cremasteric reflex, high-riding testicle
	Ovarian torsion	Sudden unilateral lower quadrant pain, nausea, adolescent females	Known ovarian cyst, severe unrelenting pain
	Diabetic ketoacidosis	Polyuria, polydipsia, weight loss, diffuse abdominal pain, vomiting	Altered mental status, Kussmaul breathing, dehydration

Age-Based Differential for Acute Abdominal Pain

Age Group	Most Common Causes	Must Not Miss
Neonates (0-28 days)	Colic, constipation, cow’s milk protein allergy, gastroesophageal reflux	Malrotation with volvulus, necrotizing enterocolitis, Hirschsprung disease, incarcerated hernia, intestinal atresia
Infants (1-12 months)	Colic (up to 4 months), gastroenteritis, constipation, viral illness	Intussusception, incarcerated hernia, volvulus, pyloric stenosis (early infancy)
Toddlers (1-3 years)	Gastroenteritis, constipation, viral illness, urinary tract infection	Intussusception, appendicitis, foreign body ingestion, incarcerated hernia
School-age (4-12 years)	Constipation, gastroenteritis, functional pain, streptococcal pharyngitis, mesenteric lymphadenitis	Appendicitis, diabetic ketoacidosis, Henoch-Schönlein purpura, inflammatory bowel disease
Adolescents (13-18 years)	Constipation, gastroenteritis, dysmenorrhea, functional pain, musculoskeletal pain	Appendicitis, ovarian torsion, ectopic pregnancy, testicular torsion, pelvic inflammatory disease

Chronic or Recurrent Abdominal Pain (Duration: Greater than 4 weeks or ≥3 episodes in 3 months)

Step-by-Step Approach to Chronic Abdominal Pain:

Step 1: Identify and address red flags — weight loss, growth failure, nocturnal pain, blood in stool, fever, family history of inflammatory bowel disease
Step 2: Rule out common organic causes — constipation (most common!), celiac disease, Helicobacter pylori infection, lactose intolerance
Step 3: If no red flags and organic workup negative, consider functional abdominal pain disorders (most common cause of chronic pain)
Step 4: Apply Rome IV criteria for specific functional gastrointestinal disorder diagnosis

Probability	Condition	Approximate Frequency	Key Distinguishing Features
COMMON	Functional abdominal pain disorders	~50-75% of chronic cases	Periumbilical pain, no red flags, normal growth, does not wake from sleep, may have school-related pattern
	Chronic constipation	~10-25%	Infrequent hard stools, fecal masses on examination, responds to laxatives, may have encopresis
	Lactose intolerance	~5-10%	Bloating, diarrhea, cramping after dairy intake; more common in certain ethnic groups
	Abdominal migraine	~5-10%	Episodic midline pain with pallor, anorexia, nausea, vomiting; family history of migraine
LESS COMMON	Celiac disease	~1-3%	Diarrhea, bloating, weight loss or poor growth, iron deficiency anemia, dermatitis herpetiformis
	Helicobacter pylori gastritis	~1-5%	Epigastric pain, worse with meals or on empty stomach; may have family history
	Inflammatory bowel disease	~1-3%	Diarrhea (often bloody), weight loss, growth failure, extraintestinal manifestations, family history
	Chronic appendicitis or recurrent appendicitis	~1%	Recurrent right lower quadrant pain, episodic, may have elevated inflammatory markers during episodes
UNCOMMON BUT IMPORTANT	Peptic ulcer disease	<1%	Epigastric pain, nocturnal symptoms, relief with antacids, hematemesis or melena
	Eosinophilic esophagitis/gastroenteritis	<1%	Dysphagia, food impaction, vomiting, abdominal pain, often with atopic history
	Cholelithiasis	<1% (increasing)	Right upper quadrant or epigastric pain, post-prandial, associated with obesity, hemolytic disease
	Chronic pancreatitis	<1%	Epigastric pain radiating to back, associated with genetic conditions, recurrent episodes

Functional Abdominal Pain Disorders (Rome IV Criteria)

Disorder	Key Criteria	Associated Features
Functional dyspepsia	Epigastric pain or burning, early satiety, or postprandial fullness; ≥4 days/month for ≥2 months	Symptoms not explained by structural disease after appropriate evaluation
Irritable bowel syndrome	Abdominal pain ≥4 days/month associated with defecation, change in stool frequency, or change in stool form; for ≥2 months	May be diarrhea-predominant, constipation-predominant, or mixed
Abdominal migraine	Paroxysmal episodes of intense periumbilical, midline, or diffuse pain lasting ≥1 hour; stereotypical pattern; interferes with activities	Associated with anorexia, nausea, vomiting, pallor; family history of migraine
Functional abdominal pain — not otherwise specified	Episodic or continuous abdominal pain ≥4 times/month for ≥2 months; does not meet criteria for other functional disorders	Insufficient criteria for irritable bowel syndrome, functional dyspepsia, or abdominal migraine

Anatomical Approach to Differential Diagnosis

Right Upper Quadrant

Hepatitis

Cholecystitis (rare)

Cholelithiasis

Right lower lobe pneumonia

Fitz-Hugh-Curtis syndrome

Subhepatic appendicitis

Left Upper Quadrant

Splenic pathology (rare)

Left lower lobe pneumonia

Gastritis

Peptic ulcer disease

Pancreatitis (radiates to back)

Constipation (splenic flexure)

Right Lower Quadrant

Appendicitis

Mesenteric lymphadenitis

Ovarian pathology

Inguinal hernia

Crohn disease (terminal ileitis)

Meckel diverticulitis

Psoas abscess

Left Lower Quadrant

Constipation (most common)

Ovarian pathology

Inguinal hernia

Inflammatory bowel disease

Testicular torsion (referred)

Renal/ureteral calculus

Periumbilical

Functional abdominal pain (most common)
Early appendicitis
Gastroenteritis
Small bowel obstruction
Umbilical hernia
Abdominal migraine

Suprapubic

Urinary tract infection
Constipation
Bladder distension
Dysmenorrhea
Pelvic inflammatory disease
Pregnancy-related

Surgical vs. Non-Surgical Causes

Category	Conditions	Key Identifiers
Surgical Emergencies	Appendicitis, malrotation with volvulus, intussusception (if not reducible), incarcerated hernia, testicular torsion, ovarian torsion, perforated viscus	Peritoneal signs, bilious vomiting, ischemic symptoms, hemodynamic instability, non-reducible mass
Urgent Surgical Consult	Suspected appendicitis, bowel obstruction, Meckel diverticulum with bleeding, trauma with solid organ injury	Progressive symptoms, localized peritoneal signs, significant gastrointestinal bleeding
Medical Management	Gastroenteritis, constipation, urinary tract infection, pancreatitis, inflammatory bowel disease, functional pain	No peritoneal signs, identifiable medical cause, stable patient

Extra-Abdominal Causes of Abdominal Pain

System	Conditions	Key Clinical Clues
Pulmonary	Lower lobe pneumonia, pleuritis, asthma	Cough, tachypnea, decreased breath sounds, fever
Cardiac	Myocarditis, pericarditis	Chest pain, tachycardia out of proportion, cardiomegaly
Genitourinary	Testicular torsion, epididymitis, urinary tract infection, pyelonephritis	Testicular examination abnormalities, dysuria, costovertebral angle tenderness
Musculoskeletal	Psoas abscess, diskitis, vertebral osteomyelitis, abdominal wall strain	Pain with hip flexion/extension, spine tenderness, positive Carnett sign
Metabolic	Diabetic ketoacidosis, adrenal crisis, hypercalcemia, porphyria	Polyuria/polydipsia, electrolyte abnormalities, altered mental status
Hematologic	Sickle cell crisis, Henoch-Schönlein purpura, hemolytic uremic syndrome	Known sickle cell disease, purpuric rash, thrombocytopenia
Infectious	Streptococcal pharyngitis, infectious mononucleosis, herpes zoster	Pharyngitis, splenomegaly, dermatomal rash
Toxins/Drugs	Lead poisoning, iron toxicity, drug ingestion	History of ingestion or exposure, associated symptoms

Drug-Induced Abdominal Pain

Drug or Drug Class	Mechanism	Characteristics	Management
Non-steroidal anti-inflammatory drugs	Prostaglandin inhibition → decreased mucosal protection	Epigastric pain, gastritis, peptic ulcer disease	Discontinue; consider proton pump inhibitor
Antibiotics	Altered gut microbiome; direct irritation	Diarrhea, cramping; may cause Clostridioides difficile colitis	Probiotics; test for C. difficile if severe
Corticosteroids	Decreased mucosal defense; immunosuppression	Peptic ulcer disease, pancreatitis, bowel perforation (masked symptoms)	Consider gastroprotection; maintain high suspicion
Iron supplements	Direct gastric irritation; constipation	Epigastric discomfort, nausea, constipation	Take with food; consider alternative formulation
Opioids	Decreased gut motility	Constipation, bloating, cramping	Stool softeners, stimulant laxatives
Valproic acid	Mitochondrial toxicity; metabolic effects	Pancreatitis, hepatotoxicity	Discontinue; monitor amylase/lipase and liver function
Chemotherapy agents	Mucositis; immunosuppression	Mucositis, typhlitis (neutropenic enterocolitis)	Supportive care; consider typhlitis in neutropenic patients
Azathioprine/6-mercaptopurine	Direct pancreatic toxicity	Pancreatitis (early in treatment course)	Discontinue; usually contraindicates rechallenge

Quick Reference: “If You See This, Think This First”

Clinical Clue	Think This First	Immediate Next Step
Bilious (green) vomiting in neonate	Malrotation with volvulus	Emergent upper gastrointestinal series; surgical consult
Colicky pain with “currant jelly” stool in infant	Intussusception	Ultrasound; air or contrast enema reduction
Pain migration periumbilical → right lower quadrant	Appendicitis	Surgical consult; consider imaging if diagnosis uncertain
Abdominal pain with absent cremasteric reflex	Testicular torsion	Emergent urological consult; do not delay for imaging
Sudden lower quadrant pain in adolescent female	Ovarian torsion	Pelvic ultrasound; gynecological consult
Abdominal pain with purpuric rash on legs	Henoch-Schönlein purpura	Urinalysis; monitor for intussusception
Pain with polyuria, polydipsia, weight loss	Diabetic ketoacidosis	Blood glucose; venous blood gas; electrolytes
Abdominal pain with pharyngitis	Streptococcal pharyngitis with mesenteric adenitis	Rapid strep test or throat culture
Right lower quadrant pain with recent upper respiratory infection	Mesenteric lymphadenitis (but rule out appendicitis)	Serial examinations; imaging if appendicitis cannot be excluded
Irreducible inguinal swelling with vomiting	Incarcerated inguinal hernia	Attempt reduction (if not toxic); surgical consult
Chronic diarrhea with weight loss and growth failure	Inflammatory bowel disease or celiac disease	Inflammatory markers, celiac serology, consider endoscopy
Periumbilical pain, normal examination, no red flags	Functional abdominal pain	Thorough history; limited workup; reassurance and management

6. Diagnostic Investigations

A stepwise, cost-effective approach guided by clinical suspicion

Investigations in pediatric abdominal pain should be guided by clinical presentation, age, and suspected diagnosis. Not all children require extensive testing — many cases of acute abdominal pain can be diagnosed clinically and managed conservatively. However, when serious pathology is suspected, timely and appropriate investigations are critical.

Guiding Principles for Pediatric Investigations

Minimize radiation exposure: Use ultrasound as first-line imaging when possible; follow ALARA (As Low As Reasonably Achievable) principles
Consider sedation needs: Young children may require sedation for CT or MRI, adding time and risk
Age-appropriate reference ranges: Normal values vary significantly by age
Serial examination may be diagnostic: In stable patients with unclear diagnosis, observation with serial examinations can be more informative than immediate imaging

First-Line Investigations for Acute Abdominal Pain

Investigation	Purpose	What to Look For	Practical Points
Urinalysis	Screen for urinary tract infection, hematuria, glycosuria	Leukocyte esterase, nitrites, blood, glucose, ketones	Clean catch or catheterized specimen in young children; bag specimens have high contamination rates
Urine pregnancy test (β-hCG)	Rule out pregnancy in females of reproductive age	Positive or negative	MUST be performed in ALL females of reproductive potential with abdominal pain; ectopic pregnancy is life-threatening
Complete blood count	Assess for infection, anemia, thrombocytopenia	White blood cell count, differential, hemoglobin, platelets	Leukocytosis with left shift suggests bacterial infection; normal white blood cell count does not exclude appendicitis (especially early)
C-reactive protein	Inflammatory marker	Elevated in infection, inflammation	Takes 12-24 hours to rise; normal early in disease; very elevated (>100 mg/L) suggests perforation or severe infection
Basic metabolic panel	Assess hydration, electrolytes, renal function	Sodium, potassium, chloride, bicarbonate, blood urea nitrogen, creatinine, glucose	Check glucose if diabetic ketoacidosis suspected; low bicarbonate indicates acidosis
Blood glucose	Screen for diabetic ketoacidosis	Hyperglycemia (>200 mg/dL with symptoms)	Can be done with point-of-care testing for rapid result

Second-Line Laboratory Investigations

Investigation	When to Order	What to Look For	Interpretation
Liver function tests	Right upper quadrant pain, jaundice, suspected hepatobiliary disease	Aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, bilirubin, albumin	Elevated transaminases = hepatocellular injury; elevated alkaline phosphatase/bilirubin = biliary obstruction
Lipase (preferred) or amylase	Epigastric pain radiating to back, suspected pancreatitis	Elevated (>3× upper limit of normal diagnostic for pancreatitis)	Lipase more specific than amylase; amylase can be elevated in other conditions
Venous blood gas	Suspected diabetic ketoacidosis, shock, sepsis	pH, pCO2, bicarbonate, lactate	Metabolic acidosis with elevated anion gap in diabetic ketoacidosis; elevated lactate in shock/ischemia
Lactate	Suspected bowel ischemia, shock, sepsis	Elevated (>2 mmol/L concerning; >4 mmol/L severely elevated)	Elevated in tissue hypoperfusion; can indicate mesenteric ischemia
Procalcitonin	Differentiating bacterial from viral infection	Elevated in bacterial infection	More specific for bacterial infection than C-reactive protein; helpful in equivocal cases
Stool studies	Diarrhea, bloody stool, suspected infectious gastroenteritis	Bacterial culture, ova and parasites, Clostridioides difficile toxin, viral panel	Consider C. difficile if recent antibiotic use; rotavirus/norovirus common in young children
Fecal calprotectin	Chronic abdominal pain, suspected inflammatory bowel disease	Elevated (>50 μg/g suggestive; >250 μg/g highly suggestive)	Marker of intestinal inflammation; helps differentiate inflammatory bowel disease from functional pain
Erythrocyte sedimentation rate	Chronic symptoms, suspected inflammatory or autoimmune condition	Elevated with inflammation	Non-specific; rises slowly; useful for chronic conditions

Imaging Studies

Ultrasound — First-Line Imaging for Most Pediatric Abdominal Pain

Why Ultrasound First?

Ultrasound is the preferred initial imaging modality in pediatric abdominal pain because:

No ionizing radiation
No sedation required
Excellent for common pediatric conditions (intussusception, appendicitis, ovarian pathology)
Can be performed at bedside in unstable patients
Real-time assessment of bowel peristalsis and blood flow

Ultrasound Type	Indications	Key Findings
Abdominal ultrasound	Right upper quadrant pain, suspected appendicitis, abdominal mass, intussusception	Appendix >6 mm diameter, target sign (intussusception), gallstones, free fluid
Pelvic ultrasound	Lower abdominal/pelvic pain in females, suspected ovarian pathology	Ovarian cysts, torsion (enlarged ovary with absent/decreased flow), ectopic pregnancy
Testicular ultrasound with Doppler	Testicular pain, suspected torsion	Absent or decreased blood flow (torsion), epididymal enlargement (epididymitis)
Renal ultrasound	Flank pain, hematuria, urinary tract infection	Hydronephrosis, stones, renal abscess
Pyloric ultrasound	Projectile vomiting in infant 2-8 weeks old	Pyloric muscle thickness >3 mm, length >15 mm

Plain Radiography

Study	Indications	Key Findings	Limitations
Abdominal radiograph (supine and upright or decubitus)	Suspected obstruction, perforation, constipation, foreign body	Air-fluid levels, dilated bowel loops, free air, fecal loading, radiopaque foreign body	Limited sensitivity for early obstruction; does not visualize appendix
Chest radiograph	Suspected pneumonia, free air under diaphragm	Infiltrates, pleural effusion, subdiaphragmatic free air	Required before upright abdominal film if perforation suspected

Computed Tomography

Radiation Considerations in Children

CT scan delivers significant ionizing radiation. Children are more sensitive to radiation effects due to rapidly dividing cells and longer life expectancy. Use CT judiciously:

Consider ultrasound or MRI as alternatives when appropriate
Use pediatric-specific low-dose protocols
Reserve CT for cases where the benefit clearly outweighs the risk
One CT scan in childhood is associated with a small but measurable increase in lifetime cancer risk

CT Type	Indications	Key Findings
CT abdomen/pelvis with intravenous contrast	Equivocal ultrasound for appendicitis, suspected abscess, trauma, complicated appendicitis	Appendiceal thickening/enhancement, abscess, free fluid, solid organ injury
CT without contrast	Renal colic, urolithiasis	Stones, hydronephrosis, ureteral dilation
CT angiography	Suspected mesenteric ischemia, vascular injury	Vascular occlusion, bowel wall enhancement pattern

Contrast Studies

Study	Indications	Key Findings
Upper gastrointestinal series	Suspected malrotation, gastric outlet obstruction, esophageal pathology	Abnormal position of duodenojejunal junction (malrotation), “corkscrew” appearance (volvulus), string sign (pyloric stenosis)
Contrast enema (air or water-soluble)	Intussusception (diagnostic and therapeutic), suspected Hirschsprung disease	Target sign, successful reduction (intussusception); transition zone (Hirschsprung)

MRI

Study	Indications	Advantages	Limitations
MRI abdomen/pelvis	Equivocal appendicitis when avoiding radiation (especially pregnant adolescents), inflammatory bowel disease evaluation, complex pelvic pathology	No radiation, excellent soft tissue contrast	Longer scan time, may require sedation in young children, limited availability
MR enterography	Inflammatory bowel disease — assess extent, activity, complications	Evaluates small bowel inflammation, strictures, fistulae	Requires oral contrast and cooperation

Targeted Investigations by Suspected Etiology

If Suspecting Appendicitis

First-Line Tests

Complete blood count: Leukocytosis (>10,000/μL) with left shift in ~80% of cases
C-reactive protein: Often elevated; very high levels suggest perforation
Urinalysis: Rule out urinary tract infection; mild pyuria can occur with appendicitis
Abdominal ultrasound: First-line imaging — sensitivity 88%, specificity 94% when appendix visualized

Second-Line Tests

CT abdomen/pelvis: If ultrasound non-diagnostic and clinical suspicion remains; sensitivity >95%
MRI: Alternative to CT to avoid radiation if available
Pediatric Appendicitis Score or Alvarado Score: Clinical scoring tools to stratify risk

If Suspecting Intussusception

First-Line Tests

Abdominal ultrasound: “Target” or “doughnut” sign on transverse view; “pseudokidney” sign on longitudinal view; sensitivity >95%
Complete blood count: May show leukocytosis

Therapeutic Intervention

Air or hydrostatic enema: Both diagnostic and therapeutic; success rate 80-95%
Surgical consultation: Required before reduction attempt
Abdominal radiograph: May show soft tissue mass, obstruction pattern

If Suspecting Malrotation with Volvulus

Emergency Investigation

Upper gastrointestinal series: Gold standard — abnormal position of duodenojejunal junction (should be left of spine at level of pylorus); “corkscrew” duodenum with volvulus
Do NOT delay for ultrasound if clinical suspicion high — proceed directly to upper gastrointestinal series and surgical consultation
Abdominal radiograph: May be normal or show “double bubble” sign, gasless abdomen, or dilated stomach

If Suspecting Inflammatory Bowel Disease

Laboratory Workup

Complete blood count: Anemia, thrombocytosis, leukocytosis
Inflammatory markers: Elevated C-reactive protein, erythrocyte sedimentation rate
Albumin: Low with severe disease or protein-losing enteropathy
Fecal calprotectin: Elevated (>250 μg/g highly suggestive)
Stool studies: Rule out infectious causes

Definitive Testing

Upper and lower endoscopy with biopsies: Gold standard for diagnosis
MR enterography: Assess small bowel involvement, strictures, fistulae
Video capsule endoscopy: Visualize small bowel mucosa if MR enterography inconclusive

If Suspecting Celiac Disease

Serological Testing

Tissue transglutaminase immunoglobulin A antibody (tTG-IgA): First-line screening test
Total serum immunoglobulin A: Must check to rule out IgA deficiency (false negative tTG-IgA)
If IgA deficient: Use tTG-IgG or deamidated gliadin peptide IgG

Confirmatory Testing

Upper endoscopy with duodenal biopsies: Gold standard — shows villous atrophy, crypt hyperplasia, intraepithelial lymphocytosis
Important: Patient must be on gluten-containing diet for accurate testing
HLA typing: DQ2/DQ8 — high negative predictive value

If Suspecting Functional Abdominal Pain

Limited Workup Approach

If history and examination suggest functional abdominal pain with no red flags, extensive testing is not indicated and may reinforce illness behavior. Consider:

Baseline: Complete blood count, C-reactive protein, urinalysis
If diarrhea present: Add fecal calprotectin, celiac serology
If constipation suspected: Consider abdominal radiograph (though clinical diagnosis usually sufficient)
Important: A positive diagnosis based on Rome IV criteria — NOT a diagnosis of exclusion

Empiric Treatment Trials as Diagnostic Tools

Sequential Empiric Therapy Approach for Chronic Abdominal Pain

When initial workup is negative but symptoms persist, empiric treatment trials can serve as diagnostic tools. Response to therapy supports the diagnosis.

Trial 1 — Constipation treatment: Polyethylene glycol 0.5-1 g/kg/day for 2-4 weeks — response suggests functional constipation as contributor
Trial 2 — Acid suppression: Proton pump inhibitor for 4-8 weeks if epigastric pain or dyspepsia — response suggests acid-related disease
Trial 3 — Lactose-free diet: Strict lactose elimination for 2-4 weeks — improvement suggests lactose intolerance
Trial 4 — Antispasmodic: Hyoscine or dicyclomine for 2-4 weeks — response supports irritable bowel syndrome

Age-Specific Investigation Considerations

Age Group	Special Considerations	Preferred Approaches
Neonates	Higher radiation sensitivity; difficult venous access; sepsis must be considered	Ultrasound first; upper gastrointestinal series for bilious vomiting; blood culture if infection suspected
Infants	Cannot cooperate with examination; catheterized urine specimen needed for accurate urinalysis	Ultrasound for most indications; low threshold for investigating urinary tract infection
Toddlers/Preschool	May require sedation for CT/MRI; verbal description unreliable	Ultrasound preferred; clinical observation valuable; parental observation important
School-age	Can cooperate with examination and history; functional pain common	Targeted workup based on clinical features; avoid over-testing for functional pain
Adolescents	Pregnancy test mandatory in females; sexually transmitted infections possible	Confidential history; urine pregnancy test; consider pelvic examination if sexually active

Summary: Investigation Pathway by Presentation

Presentation	First-Line Investigations	Second-Line if Needed
Acute right lower quadrant pain	Complete blood count, C-reactive protein, urinalysis, pregnancy test, ultrasound	CT if ultrasound non-diagnostic
Bilious vomiting in neonate	Upper gastrointestinal series (emergent), abdominal radiograph	Surgical consultation — do not delay
Colicky pain in infant with bloody stool	Ultrasound (intussusception), complete blood count	Air/contrast enema (diagnostic and therapeutic)
Chronic abdominal pain with diarrhea	Complete blood count, C-reactive protein, fecal calprotectin, celiac serology	Endoscopy with biopsies; MR enterography
Chronic periumbilical pain, no red flags	Complete blood count, C-reactive protein, urinalysis (limited workup)	Usually no further testing needed if Rome IV criteria met
Lower abdominal pain in adolescent female	Pregnancy test, urinalysis, pelvic ultrasound	Gynecological consultation if torsion or pelvic inflammatory disease suspected

7. Pattern Recognition and Clinical Decision-Making

Practical algorithms and decision pathways for pediatric abdominal pain

Clinical decision-making in pediatric abdominal pain requires rapid triage to identify surgical emergencies while avoiding unnecessary interventions for self-limiting conditions. This section provides practical algorithms organized by urgency, duration, and clinical scenarios to guide management decisions.

Step 1: Is This Urgent? — Triage Assessment

Clinical Scenario	Urgency Level	Immediate Action
Bilious vomiting in neonate or infant	EMERGENT	Nothing by mouth; nasogastric tube; intravenous access; emergent upper gastrointestinal series; immediate surgical consult
Signs of shock (tachycardia, poor perfusion, altered mental status)	EMERGENT	Intravenous fluid resuscitation; oxygen; continuous monitoring; surgical consult; consider sepsis workup
Rigid abdomen with involuntary guarding	EMERGENT	Nothing by mouth; intravenous access; surgical consult; imaging as indicated
Testicular pain with absent cremasteric reflex	EMERGENT	Immediate urological consult; do NOT delay for imaging — 6-hour window for salvage
Inconsolable infant with episodic pain and lethargy	EMERGENT	Urgent ultrasound for intussusception; surgical consult; prepare for enema reduction
Localized right lower quadrant tenderness with fever	URGENT	Laboratory studies; ultrasound; surgical consult; keep nothing by mouth pending evaluation
Irreducible inguinal swelling	URGENT	Attempt gentle reduction if patient non-toxic; surgical consult; emergent operation if irreducible
Sudden severe lower quadrant pain in adolescent female	URGENT	Pregnancy test; pelvic ultrasound; gynecological consult if ovarian torsion suspected
Abdominal pain with polyuria, polydipsia, and fruity breath	URGENT	Point-of-care glucose; venous blood gas; electrolytes; initiate diabetic ketoacidosis protocol if confirmed
Diffuse crampy pain with vomiting and diarrhea, sick contacts	ROUTINE	Assess hydration; supportive care; oral rehydration if tolerated; return precautions
Chronic periumbilical pain, normal examination, no red flags	ROUTINE	Thorough history; reassurance; consider limited workup; follow-up with primary care or gastroenterology
Constipation with palpable fecal masses	ROUTINE	Disimpaction if needed; initiate laxative regimen; dietary counseling; follow-up

Step 2: Classify by Duration

Acute (Less than 1 week)

Priority: Rule out surgical emergency

Approach: Focused history and examination; targeted investigations based on clinical suspicion

Proceed to Algorithm A

Subacute (1 to 4 weeks)

Priority: Identify evolving pathology

Approach: Monitor for progression; consider investigations if not improving

Proceed to Algorithm B

Chronic/Recurrent (Greater than 4 weeks)

Priority: Exclude organic disease; diagnose functional disorder

Approach: Systematic workup; apply Rome IV criteria; biopsychosocial assessment

Proceed to Algorithm C

Step 3: Follow the Appropriate Algorithm

Algorithm A: Acute Abdominal Pain

Clinical Scenario	Most Likely Diagnosis	Immediate Action	Disposition
Neonate with bilious vomiting ± abdominal distension	Malrotation with volvulus until proven otherwise	Emergent upper gastrointestinal series; surgical consult	Admission; likely operative intervention
Infant 3-12 months with colicky pain, drawing up legs, lethargy between episodes	Intussusception	Ultrasound; air/contrast enema reduction if confirmed	Admission for observation post-reduction; surgery if failed reduction
Child with periumbilical pain migrating to right lower quadrant, anorexia, low-grade fever	Appendicitis	Laboratory studies; ultrasound; surgical consult	Admission; appendectomy
Infant with projectile non-bilious vomiting, hungry after vomiting, age 2-8 weeks	Pyloric stenosis	Pyloric ultrasound; electrolytes (hypochloremic metabolic alkalosis)	Admission; fluid resuscitation; pyloromyotomy
Inguinal swelling with pain, vomiting, non-reducible	Incarcerated inguinal hernia	Attempt reduction if non-toxic; surgical consult	Admission for observation or surgery
Male with sudden testicular or lower abdominal pain, swollen testicle	Testicular torsion	Immediate urological consult; do not delay for imaging	Emergent surgical exploration
Adolescent female with sudden unilateral lower quadrant pain, nausea	Ovarian torsion	Pregnancy test; pelvic ultrasound with Doppler	Gynecological consult; surgery if torsion confirmed
Diffuse pain, vomiting, diarrhea, sick contacts, well-appearing	Viral gastroenteritis	Assess hydration; oral rehydration therapy	Discharge with return precautions; admit if dehydrated
Right lower quadrant pain with recent upper respiratory infection, pharyngitis	Mesenteric lymphadenitis	Clinical diagnosis; consider ultrasound if appendicitis cannot be excluded	Discharge with close follow-up; serial examination if uncertain
Suprapubic pain, dysuria, fever	Urinary tract infection	Urinalysis; urine culture	Outpatient antibiotics if uncomplicated; admit if pyelonephritis or ill-appearing

Algorithm B: Subacute Abdominal Pain (1 to 4 weeks)

Clinical Scenario	Considerations	Approach
Persistent right lower quadrant pain, not worsening	Chronic or recurrent appendicitis; Crohn disease	Imaging if not done; inflammatory markers; consider gastroenterology referral
Post-infectious abdominal pain following gastroenteritis	Post-infectious irritable bowel syndrome; lactose intolerance	Reassurance; lactose-free trial; follow-up if persistent
Ongoing constipation despite initial treatment	Refractory constipation; underlying cause (Hirschsprung disease if severe)	Escalate laxative therapy; consider abdominal radiograph; referral if refractory
Recurrent episodes of similar pain with complete resolution between	Recurrent intussusception; abdominal migraine; functional pain	Ultrasound during episode; headache/migraine history; gastroenterology referral

Algorithm C: Chronic or Recurrent Abdominal Pain (Greater than 4 weeks)

Systematic Approach:

Screen for red flags — If present, investigate for organic disease
Baseline workup — Complete blood count, C-reactive protein, celiac serology, urinalysis
If diarrhea — Add fecal calprotectin, stool studies
If red flags or abnormal baseline — Refer to gastroenterology; consider endoscopy, imaging
If no red flags and normal workup — Apply Rome IV criteria; diagnose specific functional disorder
Initiate treatment — Biopsychosocial approach; dietary modification; psychological support

Red Flags Present?	Baseline Workup	Next Steps
YES — Weight loss, growth failure, bloody stool, nocturnal pain, family history of inflammatory bowel disease, persistent vomiting, localized tenderness away from umbilicus	Complete blood count, C-reactive protein, erythrocyte sedimentation rate, albumin, celiac serology, fecal calprotectin, urinalysis, stool studies	Gastroenterology referral; likely endoscopy; imaging (MR enterography if inflammatory bowel disease suspected)
NO — Periumbilical pain, normal growth, does not wake from sleep, no concerning associated symptoms	Limited: Complete blood count, C-reactive protein, urinalysis ± celiac serology	Apply Rome IV criteria; positive diagnosis of functional pain disorder; initiate treatment; reassurance

“What Do I Do If…” Decision Reference

Clinical Situation	Immediate Action	Next Step
Ultrasound shows non-visualized appendix but clinical suspicion remains	Serial abdominal examinations every 4-6 hours	CT if worsening or persistent concern; MRI as alternative; surgical consult
Intussusception reduced by enema but history of recurrence	Observation for 24 hours; resume feeding slowly	Consider investigation for lead point (Meckel diverticulum, polyp) if recurrent (>2 episodes)
Appendicitis confirmed but patient stable with contained perforation/abscess	Intravenous antibiotics; interventional radiology drainage if large abscess	Non-operative management initially; interval appendectomy in 6-8 weeks
Adolescent female with positive pregnancy test and abdominal pain	Quantitative β-hCG; pelvic ultrasound	Rule out ectopic pregnancy; obstetric/gynecological consultation
Child with functional pain diagnosis but parent demands more testing	Acknowledge concerns; explain positive diagnosis criteria	Offer limited additional testing if needed to provide reassurance; avoid extensive workup that reinforces illness behavior
Recurrent abdominal pain with normal basic workup but ongoing symptoms	Detailed dietary and symptom diary; psychosocial assessment	Gastroenterology referral; consider empiric treatment trials; cognitive behavioral therapy referral
Abdominal pain resolved but parents want diagnosis	Explain likely viral or self-limited etiology	Reassurance; return precautions; follow-up with primary care if recurrent
Constipation not responding to polyethylene glycol	Ensure adequate dosing (may need 1-1.5 g/kg/day); assess compliance	Add stimulant laxative; consider disimpaction; evaluate for underlying cause
Right lower quadrant tenderness but all tests normal	Serial examination; do not discharge if clinical suspicion high	Observation admission; repeat imaging in 12-24 hours if symptoms persist; surgical consult
Henoch-Schönlein purpura with severe abdominal pain	Monitor closely for intussusception (ileoileal common)	Ultrasound if pain severe or worsening; consider corticosteroids for severe abdominal involvement

Age-Specific Decision Pathways

Age Group	Key Decision Points	When to Involve Specialists
Neonates	Any bilious vomiting = emergent surgical evaluation; abdominal distension + feeding intolerance = high concern; low threshold for investigation	Pediatric surgery for any suspected surgical condition; neonatology for premature infants
Infants	Inconsolable crying requires thorough evaluation; intussusception peaks at 5-9 months; incarcerated hernia common	Pediatric surgery if intussusception or hernia; pediatric gastroenterology if feeding issues, failure to thrive
Toddlers	Localization unreliable; behavior changes more informative; consider foreign body ingestion	Pediatric surgery if appendicitis suspected; toxicology if ingestion
School-age	Appendicitis peak incidence; functional pain common; can give more reliable history	Pediatric surgery for appendicitis; gastroenterology for chronic symptoms; psychology for functional pain with significant impact
Adolescents	Always consider pregnancy; sexually transmitted infections possible; ovarian/testicular pathology; similar causes to adults	Gynecology for ovarian pathology; urology for testicular issues; adolescent medicine for complex psychosocial situations

Troubleshooting Refractory Abdominal Pain

When Pain Persists Despite Initial Management — Ask These Questions

Is the diagnosis correct? — Reconsider differential; have any new symptoms developed?
Was treatment adequate? — Correct medication, dose, duration, and compliance?
Are there multiple overlapping causes? — Constipation AND functional pain; reflux AND anxiety
Are psychosocial factors being addressed? — Anxiety, school issues, family stressors
Is there unrecognized organic disease? — Consider repeat/additional investigations
Has the condition evolved? — New pathology may have developed
Is specialist input needed? — Gastroenterology, surgery, psychology, pain team

Disposition Decision Guide

Disposition	Criteria	Requirements Before Discharge/Transfer
Discharge Home	Diagnosis clear and non-surgical; tolerating oral intake; adequate pain control; reliable follow-up; caregivers understand return precautions	Written discharge instructions; specific return precautions; follow-up arranged
Observation (Emergency Department or Short Stay)	Diagnosis uncertain; need for serial examinations; awaiting investigation results; mild dehydration requiring intravenous fluids	Clear re-evaluation plan; criteria for admission or discharge defined
Admission (Medical)	Confirmed medical diagnosis requiring inpatient treatment; moderate-severe dehydration; need for intravenous antibiotics; diagnostic workup requiring inpatient monitoring	Admission orders; specialist consultation as needed
Admission (Surgical)	Confirmed or highly suspected surgical condition; need for operative intervention	Surgical team notified; preoperative preparation; consent
Transfer to Higher Level of Care	Pediatric surgery not available; need for subspecialty care not locally available; intensive care required	Accepting physician confirmed; appropriate transport arranged; all records transferred

8. Clinical Pearls and Pitfalls

Practical wisdom — learn from successes and avoid common mistakes

Must-Know Clinical Pearls

Bilious vomiting in a neonate is volvulus until proven otherwise: This is a true surgical emergency. Do not delay — order an emergent upper gastrointestinal series and call the surgeon immediately. Minutes matter for bowel survival.

Always examine the genitalia: Testicular torsion and incarcerated inguinal hernias can present with abdominal pain alone. Missing testicular torsion means losing the testicle. Make genital examination routine in every child with abdominal pain.

The classic presentation is the exception, not the rule: Classic appendicitis migration occurs in only 50-60% of cases. The intussusception triad is present in only 20-40%. Atypical presentations are common — maintain a high index of suspicion.

Constipation is extremely common and frequently overlooked: It is the most common cause of chronic abdominal pain in children. Always ask about stool frequency and consistency. Palpate for fecal masses. Treat aggressively — it often coexists with other conditions.

Functional abdominal pain is a positive diagnosis: Use Rome IV criteria to make the diagnosis — it is NOT a diagnosis of exclusion. Extensive testing in the absence of red flags reinforces illness behavior and does not help the child.

The child who hops without pain probably does not have peritonitis: Use the hop test, cough test, or shake test as alternatives to rebound tenderness, which is unreliable and distressing in children.

Serial examination is a powerful diagnostic tool: When the diagnosis is uncertain, observation with serial examinations every 4-6 hours often clarifies the picture. Pathology declares itself over time.

Ultrasound first in children: Ultrasound should be the first-line imaging modality for most pediatric abdominal conditions. It has no radiation, requires no sedation, and is highly accurate for common conditions like appendicitis and intussusception.

Pregnancy test in ALL adolescent females: Ectopic pregnancy is life-threatening. Perform a urine pregnancy test on every female of reproductive potential with abdominal pain, regardless of reported sexual history.

Streptococcal pharyngitis commonly causes abdominal pain: Always examine the throat in children with abdominal pain, especially if they have fever. Mesenteric lymphadenitis from streptococcal infection can mimic appendicitis.

Critical Pitfalls to Avoid

Assuming bilious vomiting is “just reflux” or viral: Green or yellow-green vomiting in a neonate or infant requires emergent evaluation for malrotation with volvulus. This diagnosis cannot wait — delay leads to bowel necrosis and death.

Relying on a normal white blood cell count to exclude appendicitis: Up to 20-30% of children with appendicitis have a normal white blood cell count, especially early in the disease course. Clinical assessment trumps laboratory values.

Not examining the testicles in boys with abdominal pain: Young children may not report testicular pain and may only complain of abdominal discomfort. A missed testicular torsion results in testicular loss. Always examine the scrotum.

Discharging a child with unexplained localized tenderness: Localized tenderness, especially in the right lower quadrant, warrants either diagnosis, observation, or imaging. Do not discharge unless you have an explanation or clear follow-up plan.

Attributing severe pain to “just constipation” without examination: While constipation is common, severe pain, especially with peritoneal signs, requires further evaluation. Constipation can coexist with surgical pathology.

Ordering CT scan as first-line imaging in stable children: CT delivers significant radiation and increases lifetime cancer risk. Use ultrasound first. Reserve CT for cases where ultrasound is non-diagnostic and clinical suspicion remains high.

Missing diabetic ketoacidosis presenting as abdominal pain: Abdominal pain is a presenting symptom in up to 50% of new-onset diabetes. Check blood glucose in any child with unexplained abdominal pain, vomiting, or altered mental status.

Forgetting extra-abdominal causes: Lower lobe pneumonia, streptococcal pharyngitis, and urinary tract infection are common causes of abdominal pain. Listen to the lungs, examine the throat, and check a urinalysis.

Dismissing functional pain as “not real”: Functional abdominal pain causes real suffering and significantly impacts quality of life. Dismissing the child’s symptoms damages the therapeutic relationship and delays appropriate treatment.

Assuming a well-appearing child between episodes is fine: Children with intussusception may appear completely well between episodes of pain. Lethargy or pallor between episodes is particularly concerning and suggests ongoing pathology.

Key Takeaways

Pediatric abdominal pain differential varies significantly by age — always consider age-specific emergencies (volvulus in neonates, intussusception in infants, appendicitis in school-age children).
Surgical emergencies account for only 1-8% of pediatric abdominal pain presentations, but identifying them is critical — know the red flags.
Bilious vomiting in a neonate is malrotation with volvulus until proven otherwise — this is a time-critical emergency.
Classic presentations are often absent — atypical appendicitis, intussusception without the triad, and early presentations may have minimal findings.
Constipation is the most common cause of chronic abdominal pain in children and frequently coexists with other conditions — always assess and treat it.
Functional abdominal pain disorders affect 10-25% of school-aged children and should be diagnosed using Rome IV criteria as a positive diagnosis, not as exclusion.
Ultrasound is the preferred first-line imaging modality in children — it has no radiation and is highly accurate for common pediatric conditions.
Always examine the genitalia (testicles in boys, consider pelvic examination in sexually active adolescent females) — torsion is a time-critical diagnosis.
Perform a pregnancy test in all adolescent females with abdominal pain — ectopic pregnancy is life-threatening.
Serial examination is a valuable diagnostic tool — when uncertain, observation with re-evaluation often clarifies the diagnosis.
The biopsychosocial model applies to all pediatric abdominal pain — psychosocial factors influence even organic disease and must be addressed.
Clear return precautions and follow-up plans are essential — conditions evolve, and parents need to know when to return.

Quick Reference Algorithm

Systematic Approach to Pediatric Abdominal Pain:

Assess urgency: Is the child hemodynamically stable? Any signs of peritonitis, obstruction, or shock? If unstable → resuscitate and emergent surgical consultation.
Screen for red flags: Bilious vomiting, bloody stool, severe localized tenderness, involuntary guarding, testicular pain, signs of shock, weight loss, nocturnal pain.
Consider age-specific emergencies: Neonates (volvulus, necrotizing enterocolitis); Infants (intussusception, incarcerated hernia); All ages (appendicitis, torsion).
Take focused history: Use “ABDOMEN” mnemonic — Attributes, Bowel/Bladder, Diet/Development, Other symptoms, Medications/Medical history, Events/Exposures, Neonatal/Family history.
Perform systematic examination: Vital signs, general inspection, abdominal examination (inspect, auscultate, palpate), genitourinary examination, check for extra-abdominal causes.
Order targeted investigations: Based on clinical suspicion — urinalysis and pregnancy test (females) are baseline; ultrasound is first-line imaging; avoid unnecessary CT radiation.
Make disposition decision: Surgical emergency → operating room; Uncertain diagnosis → observation with serial examination; Clear non-surgical diagnosis → treat and discharge with return precautions.
For chronic pain: Screen for red flags → limited baseline workup → if normal, apply Rome IV criteria → positive diagnosis of functional disorder → biopsychosocial treatment approach.

Red Flags Quick Reference Card

Immediate Action Required

Bilious (green) vomiting
Signs of shock
Rigid abdomen
Testicular pain with abnormal examination
Inconsolable infant with episodic pain
Irreducible inguinal mass

Urgent Evaluation Required

Localized right lower quadrant tenderness
Bloody stool
Severe localized pain in adolescent female
Pain waking child from sleep
Weight loss or growth failure
High fever with abdominal pain