Clinical Approach to Vomiting
Comprehensive Practical Framework1. Symptom Overview
Understanding the clinical significance and classification of vomiting
Vomiting is one of the most common presenting complaints in clinical practice, accounting for approximately 8 million emergency department visits annually in the United States alone. It represents the second most common gastrointestinal symptom after abdominal pain and affects all age groups. Nausea and vomiting occur in up to 50% of pregnant women during the first trimester and are reported by over 70% of patients receiving chemotherapy. The economic burden is substantial, with direct healthcare costs exceeding $2 billion annually, not including lost productivity and quality of life impacts.
Definition
Vomiting (emesis) is the forceful expulsion of gastric contents through the mouth, resulting from coordinated contraction of the abdominal muscles, diaphragm, and gastric wall with simultaneous relaxation of the lower esophageal sphincter. It is a complex reflex act distinct from regurgitation (passive return of gastric contents without muscular effort) and rumination (voluntary, habitual regurgitation). Nausea, the unpleasant sensation of imminent vomiting, often precedes emesis but may occur independently.
Classification by Duration
| Category | Duration | Common Causes | Clinical Significance |
|---|---|---|---|
| Acute | Less than 1 week | Viral gastroenteritis, food poisoning, medication side effects, acute gastritis, early pregnancy | Usually self-limiting; focus on hydration and identifying serious causes (obstruction, myocardial infarction, diabetic ketoacidosis) |
| Persistent | 1 to 4 weeks | Medication-induced, gastroparesis, partial obstruction, pregnancy (hyperemesis gravidarum), metabolic disorders | Requires investigation; higher risk of complications (dehydration, electrolyte disturbances, malnutrition) |
| Chronic | Greater than 4 weeks | Gastroparesis, cyclic vomiting syndrome, rumination syndrome, psychogenic vomiting, chronic intestinal pseudo-obstruction | Significant impact on quality of life; often requires specialist evaluation and multidisciplinary management |
Classification by Character
Non-Bilious Vomiting
Vomitus that is clear, white, or contains undigested food without green-yellow bile pigmentation. Suggests obstruction proximal to the ampulla of Vater or functional disorders. Common in gastric outlet obstruction, pyloric stenosis, and early-stage gastroparesis.
Bilious Vomiting
Vomitus with green or yellow bile pigmentation indicates patent communication between the duodenum and stomach. Suggests obstruction distal to the ampulla of Vater, small bowel pathology, or severe retching. Requires attention when associated with abdominal pain.
Hematemesis (Bloody Vomiting)
Vomiting of fresh red blood or “coffee-ground” material (digested blood). Fresh blood suggests active upper gastrointestinal bleeding proximal to the ligament of Treitz. Causes include peptic ulcer disease, esophageal varices, Mallory-Weiss tears, and gastric malignancy.
Feculent Vomiting
Vomitus with fecal odor and appearance, typically brown and malodorous. Indicates distal small bowel or colonic obstruction, gastrocolic fistula, or bacterial overgrowth with prolonged intestinal stasis. Represents a surgical emergency when due to obstruction.
Vomitus Characteristics and Clinical Implications
| Characteristic | Description | Likely Etiology |
|---|---|---|
| Clear or mucoid | Watery, slimy, no food particles | Gastritis, anxiety, early morning vomiting, pyloric obstruction (gastric secretions) |
| Undigested food | Recognizable food particles shortly after eating | Esophageal disorders (achalasia, diverticulum), severe gastroparesis, gastric outlet obstruction |
| Partially digested food | Food eaten hours prior, partially broken down | Gastroparesis, gastric outlet obstruction, small bowel dysmotility |
| Coffee-ground | Dark brown or black granular material | Upper gastrointestinal bleeding with gastric acid exposure (peptic ulcer, gastritis, malignancy) |
| Bright red blood | Fresh blood, may be mixed with gastric contents | Active arterial bleeding (variceal hemorrhage, Dieulafoy lesion, severe erosive disease) |
Classification by Pattern and Timing
| Pattern | Description | Suggests |
|---|---|---|
| Early morning (before breakfast) | Vomiting upon awakening or shortly after, often with minimal nausea | Pregnancy, increased intracranial pressure, uremia, alcoholic gastritis |
| Postprandial (within 1 hour of eating) | Vomiting shortly after meals, may relieve associated discomfort | Peptic ulcer disease, gastritis, psychogenic vomiting, pyloric channel ulcer |
| Delayed postprandial (1-4 hours after eating) | Vomiting of partially digested food several hours after meals | Gastroparesis, gastric outlet obstruction, small bowel obstruction |
| Projectile | Forceful vomiting without preceding nausea, expelled with significant force | Increased intracranial pressure, pyloric stenosis, proximal gastrointestinal obstruction |
| Cyclical | Stereotypical episodes of severe vomiting lasting hours to days, separated by symptom-free intervals | Cyclic vomiting syndrome, abdominal migraine, cannabinoid hyperemesis syndrome |
| Position-related | Vomiting triggered or worsened by specific positions or head movements | Vestibular disorders, increased intracranial pressure, posterior fossa lesions |
Key Concept: The “Dangerous Dozen” — While most vomiting is self-limiting, always consider these life-threatening causes that require urgent evaluation:
- Gastrointestinal emergencies: Bowel obstruction, acute appendicitis, acute pancreatitis, acute cholecystitis
- Cardiac emergencies: Acute myocardial infarction (especially inferior wall), acute heart failure
- Neurological emergencies: Increased intracranial pressure, meningitis, subarachnoid hemorrhage
- Metabolic emergencies: Diabetic ketoacidosis, adrenal crisis, uremic syndrome
Key Epidemiological Facts
- Acute gastroenteritis causes approximately 179 million episodes of acute vomiting annually in the United States
- Medication-induced nausea and vomiting affects up to 20% of patients taking common medications including antibiotics, NSAIDs, and opioids
- Gastroparesis affects approximately 4% of the population, with diabetes mellitus being the most identifiable cause
- Cyclic vomiting syndrome has a prevalence of approximately 2% in adults and is frequently misdiagnosed
- Postoperative nausea and vomiting occurs in 30-50% of surgical patients and up to 80% in high-risk populations
2. Pathophysiology and Mechanisms
Understanding the underlying mechanisms of vomiting
Vomiting is a highly coordinated reflex involving multiple neural pathways, neurotransmitters, and effector organs. Understanding the vomiting reflex arc is essential for both diagnosis and treatment, as different causes activate distinct pathways and respond to different antiemetic therapies. The central integration occurs in the “vomiting center,” a functional (rather than discrete anatomical) region in the medulla oblongata that receives input from multiple sources and coordinates the complex motor response.
The Vomiting Reflex Arc
| Component | Structure | Function |
|---|---|---|
| Receptors (Peripheral) | Gastrointestinal tract mechanoreceptors and chemoreceptors, vestibular apparatus, pharynx | Detect noxious stimuli including distension, toxins, inflammation, and motion; initiate afferent signaling |
| Receptors (Central) | Chemoreceptor trigger zone (area postrema), higher cortical centers | Detect blood-borne toxins, metabolic derangements; process emotional and anticipatory stimuli |
| Afferent Pathway | Vagus nerve (cranial nerve X), glossopharyngeal nerve (cranial nerve IX), sympathetic afferents, vestibular nerve (cranial nerve VIII) | Transmit signals from peripheral receptors to the vomiting center; vagal afferents are the primary pathway for gastrointestinal stimuli |
| Integration Center | Vomiting center in the medulla oblongata (nucleus tractus solitarius and surrounding reticular formation) | Integrates afferent input; coordinates and initiates the motor response; generates the pattern of emesis |
| Efferent Pathway | Vagus nerve, phrenic nerve (C3-C5), spinal nerves to abdominal muscles | Transmit coordinated motor commands to effector organs |
| Effectors | Diaphragm, abdominal wall muscles, gastric wall, lower esophageal sphincter, glottis, soft palate | Execute the coordinated muscle contractions and relaxations that produce emesis |
The Three Phases of Vomiting
Pre-ejection Phase
Duration: Seconds to minutes
Features: Nausea, salivation, pallor, tachycardia, cold sweating
Mechanism: Autonomic activation with retrograde giant contractions in the small intestine moving contents into the stomach
Retching Phase
Duration: Several seconds
Features: Rhythmic contractions of abdominal and respiratory muscles against a closed glottis
Mechanism: Spasmodic respiratory movements create negative intrathoracic pressure while gastric contents move into the esophagus
Ejection Phase
Duration: Seconds
Features: Forceful expulsion of gastric contents through the mouth
Mechanism: Coordinated contraction of diaphragm and abdominal muscles with relaxation of lower esophageal sphincter and elevation of soft palate
Four Major Input Pathways to the Vomiting Center
1. Chemoreceptor Trigger Zone
Location: Area postrema in the floor of the fourth ventricle
Unique feature: Outside the blood-brain barrier, allowing detection of blood-borne substances
Stimuli: Drugs (opioids, chemotherapy, digoxin), metabolic toxins (uremia, ketoacidosis), bacterial toxins
Key receptors: Dopamine D2, serotonin 5-HT3, neurokinin NK1, opioid receptors
2. Vestibular System
Location: Inner ear vestibular apparatus
Pathway: Vestibular nerve → vestibular nuclei → vomiting center
Stimuli: Motion, positional changes, vestibular disorders (labyrinthitis, Ménière disease)
Key receptors: Histamine H1, muscarinic M1 receptors
3. Gastrointestinal Tract
Location: Mechanoreceptors and chemoreceptors throughout the gut wall
Pathway: Vagal and sympathetic afferents → nucleus tractus solitarius → vomiting center
Stimuli: Distension, mucosal irritation, inflammation, obstruction, toxins
Key receptors: Serotonin 5-HT3, mechanosensitive ion channels
4. Higher Cortical Centers
Location: Cerebral cortex, limbic system, hypothalamus
Pathway: Direct connections to vomiting center
Stimuli: Anticipatory nausea, unpleasant sights/smells/tastes, pain, fear, emotional distress
Key receptors: Various neurotransmitter systems including GABA, serotonin, dopamine
Key Neurotransmitters and Receptor Targets
| Neurotransmitter | Receptor | Primary Location | Clinical Relevance |
|---|---|---|---|
| Serotonin | 5-HT3 | Chemoreceptor trigger zone, vagal afferents, gastrointestinal tract | Target of ondansetron; highly effective for chemotherapy-induced and postoperative nausea and vomiting |
| Dopamine | D2 | Chemoreceptor trigger zone | Target of metoclopramide, prochlorperazine; effective for drug-induced and metabolic causes |
| Histamine | H1 | Vestibular nuclei, vomiting center | Target of promethazine, dimenhydrinate; effective for motion sickness and vestibular disorders |
| Acetylcholine | Muscarinic M1 | Vestibular nuclei, vomiting center | Target of scopolamine; effective for motion sickness |
| Substance P | NK1 | Vomiting center, chemoreceptor trigger zone | Target of aprepitant; particularly effective for delayed chemotherapy-induced vomiting |
How Conditions Cause Vomiting
| Condition | Mechanism | Treatment Implication |
|---|---|---|
| Acute gastroenteritis | Enterochromaffin cells release serotonin in response to mucosal irritation and toxins; vagal 5-HT3 receptors activated | 5-HT3 antagonists (ondansetron) effective; supportive care with rehydration essential |
| Chemotherapy-induced nausea and vomiting | Acute phase: massive serotonin release from gut enterochromaffin cells; Delayed phase: substance P release in brainstem | Combination therapy: 5-HT3 antagonist + NK1 antagonist + dexamethasone for optimal control |
| Opioid-induced nausea and vomiting | Direct stimulation of chemoreceptor trigger zone via opioid receptors; delayed gastric emptying; vestibular sensitization | D2 antagonists, 5-HT3 antagonists; tolerance often develops within days |
| Motion sickness | Sensory mismatch between vestibular, visual, and proprioceptive inputs; histaminergic and cholinergic pathways activated | Antihistamines and anticholinergics most effective; 5-HT3 antagonists less useful |
| Gastroparesis | Delayed gastric emptying leads to gastric distension; vagal mechanoreceptors stimulated; often associated with autonomic neuropathy | Prokinetics (metoclopramide); dietary modifications; gastric electrical stimulation for refractory cases |
| Increased intracranial pressure | Direct pressure on brainstem vomiting center; often projectile without preceding nausea | Treat underlying cause; steroids for edema; surgical decompression may be needed |
| Diabetic ketoacidosis | Multiple mechanisms: ketone body stimulation of chemoreceptor trigger zone; gastroparesis; electrolyte disturbances | Insulin therapy and fluid resuscitation address the underlying cause; antiemetics as adjunct |
| Bowel obstruction | Proximal distension activates mechanoreceptors; mucosal ischemia releases inflammatory mediators; bacterial overgrowth produces toxins | Nasogastric decompression; surgical intervention often required; antiemetics for comfort |
| Cannabinoid hyperemesis syndrome | Paradoxical effect of chronic cannabis use; possible downregulation of cannabinoid receptors in gut; responds uniquely to hot water bathing | Cannabis cessation is curative; capsaicin cream may provide symptomatic relief; traditional antiemetics often ineffective |
Often Overlooked Mechanism: The Gut-Brain Axis
The gastrointestinal tract contains over 90% of the body’s serotonin, stored in enterochromaffin cells. When these cells are stimulated by chemotherapy, radiation, infection, or mechanical distension, they release massive amounts of serotonin that activate vagal afferents. This explains why 5-HT3 antagonists are so effective for gastrointestinal causes of vomiting but less useful for vestibular or central causes. Understanding which pathway is activated guides antiemetic selection.
Complications of Vomiting
| Complication | Mechanism | Clinical Features |
|---|---|---|
| Dehydration and hypovolemia | Loss of gastric fluid; inability to maintain oral intake | Tachycardia, hypotension, decreased urine output, dry mucous membranes |
| Metabolic alkalosis | Loss of gastric hydrochloric acid; renal bicarbonate retention due to volume contraction | Often asymptomatic; may cause muscle cramping, weakness, cardiac arrhythmias |
| Hypokalemia | Direct loss in vomitus; renal potassium wasting secondary to alkalosis and aldosterone activation | Weakness, cardiac arrhythmias, ileus, exacerbates alkalosis |
| Mallory-Weiss tear | Mucosal laceration at gastroesophageal junction from forceful retching | Hematemesis, typically self-limiting; occasionally requires endoscopic intervention |
| Boerhaave syndrome | Full-thickness esophageal rupture from severe vomiting | Severe chest pain, subcutaneous emphysema, shock; surgical emergency with high mortality |
| Aspiration pneumonia | Inhalation of gastric contents, especially in patients with impaired consciousness | Respiratory distress, fever, infiltrates typically in dependent lung segments |
3. History Taking
A comprehensive approach to eliciting the vomiting history
Red Flags — Require Urgent Evaluation
- Hematemesis or coffee-ground vomitus — Upper gastrointestinal bleeding
- Feculent vomiting — Distal bowel obstruction, gastrocolic fistula
- Severe abdominal pain with distension — Obstruction, perforation, ischemia
- Projectile vomiting without nausea — Increased intracranial pressure
- New severe headache — Subarachnoid hemorrhage, meningitis, mass lesion
- Altered mental status — Sepsis, metabolic emergency, intracranial pathology
- Signs of severe dehydration — Hypotension, tachycardia, oliguria
- Chest pain or dyspnea — Myocardial infarction, Boerhaave syndrome
- Diabetic patient with altered consciousness — Diabetic ketoacidosis
- Recent head trauma — Intracranial hemorrhage, elevated intracranial pressure
- Fever with neck stiffness — Meningitis, encephalitis
- Known or suspected pregnancy with severe vomiting — Hyperemesis gravidarum, ectopic pregnancy
Systematic History: The “VOMITS” Approach
Use the mnemonic “VOMITS” to ensure comprehensive history taking:
- V — Volume and Vomitus character: How much? What does it look like? Any blood, bile, or undigested food? Does it have a fecal odor?
- O — Onset and course: When did it start? Sudden or gradual? Single episode or recurrent? Is it getting better, worse, or staying the same?
- M — Meals and timing: Relationship to eating? Before, during, or after meals? How long after eating? Empty stomach vomiting?
- I — Instigating factors and associations: What triggers it? Associated symptoms (pain, headache, vertigo, diarrhea, fever)? What relieves it?
- T — Treatments and toxins: Current medications? Recent new drugs? Alcohol, cannabis, or other substance use? Any treatments tried?
- S — Systemic review and special circumstances: Weight loss? Pregnancy possible? Recent surgery or travel? Sick contacts? Impact on daily life?
Targeted Questions by Suspected Cause
| Suspected Cause | Key Features | Ask This Question |
|---|---|---|
| Acute gastroenteritis | Acute onset, diarrhea, sick contacts, food exposure | “Has anyone else who ate the same food been sick? Do you have diarrhea as well?” |
| Bowel obstruction | Colicky abdominal pain, distension, obstipation, prior surgery | “Have you passed gas or had a bowel movement today? Have you had any abdominal surgeries?” |
| Gastroparesis | Early satiety, bloating, undigested food in vomitus hours after eating | “Do you feel full after eating very little? Can you recognize food in the vomit from meals eaten hours ago?” |
| Increased intracranial pressure | Projectile vomiting, morning headache, visual changes, no nausea | “Is the vomiting forceful without warning? Is your headache worse in the morning or when lying down?” |
| Vestibular disorder | Vertigo, nystagmus, worsened by head movement | “Does the room spin? Is the nausea worse when you move your head or change position?” |
| Acute myocardial infarction | Chest discomfort, diaphoresis, risk factors, especially inferior wall | “Do you have any chest pressure, tightness, or pain? Any sweating or shortness of breath?” |
| Diabetic ketoacidosis | Known diabetes, polyuria, polydipsia, abdominal pain, fruity breath | “Do you have diabetes? Have you been urinating more than usual or feeling very thirsty?” |
| Pregnancy | Morning predominance, first trimester, food aversions | “When was your last menstrual period? Is there any chance you could be pregnant?” |
| Cyclic vomiting syndrome | Stereotypical episodes, symptom-free intervals, often with migraine history | “Do these episodes follow a pattern? Are you completely well between episodes? Do you have a history of migraines?” |
| Cannabinoid hyperemesis syndrome | Regular cannabis use, compulsive hot bathing provides relief | “Do you use cannabis? How often? Does taking a hot shower or bath make you feel better?” |
| Psychogenic vomiting | Stress-related, no weight loss, able to eat after vomiting | “Does the vomiting happen more during stressful times? Can you eat again soon after vomiting?” |
| Bulimia nervosa | Self-induced, binge eating, body image concerns | “Do you ever make yourself vomit? How do you feel about your weight and body shape?” |
Associated Symptoms and Their Significance
| Associated Symptom | Consider | Mechanism |
|---|---|---|
| Diarrhea | Gastroenteritis (viral, bacterial, parasitic), food poisoning | Shared infectious or toxic etiology affecting entire gastrointestinal tract |
| Abdominal pain (colicky) | Bowel obstruction, biliary colic, renal colic | Visceral pain from hollow organ distension or spasm |
| Abdominal pain (constant, severe) | Pancreatitis, peritonitis, mesenteric ischemia | Peritoneal inflammation or tissue ischemia |
| Headache | Migraine, increased intracranial pressure, meningitis, subarachnoid hemorrhage | Shared neural pathways or direct brainstem involvement |
| Vertigo | Vestibular neuritis, labyrinthitis, Ménière disease, posterior fossa lesion | Vestibular input to vomiting center |
| Chest pain | Myocardial infarction, Boerhaave syndrome, esophageal spasm | Vagal activation (myocardial infarction) or direct injury (Boerhaave) |
| Fever | Infection (gastroenteritis, cholecystitis, appendicitis, meningitis) | Inflammatory response; cytokines affect chemoreceptor trigger zone |
| Weight loss | Malignancy, chronic obstruction, gastroparesis, eating disorder | Reduced caloric intake, malabsorption, or catabolic state |
Medication and Substance History
Medications That Commonly Cause Vomiting
- Opioid analgesics — Direct chemoreceptor trigger zone stimulation; delayed gastric emptying
- Chemotherapy agents — Highly emetogenic (cisplatin, cyclophosphamide); serotonin release from gut
- Antibiotics — Erythromycin (prokinetic effect), metronidazole, fluoroquinolones
- Nonsteroidal anti-inflammatory drugs — Gastric irritation, prostaglandin inhibition
- Digoxin — Chemoreceptor trigger zone stimulation; indicator of toxicity
- Selective serotonin reuptake inhibitors — Serotonergic effects on gut and brain
- Theophylline — Direct chemoreceptor trigger zone stimulation
- Oral contraceptives — Estrogen-related; mimics pregnancy
- Iron supplements — Direct gastric irritation
- Levodopa and dopamine agonists — Chemoreceptor trigger zone stimulation
Substance Use History
- Alcohol: Acute intoxication, withdrawal, alcoholic gastritis, alcoholic ketoacidosis, pancreatitis
- Cannabis: Cannabinoid hyperemesis syndrome with chronic use; paradoxically, can be antiemetic in acute use
- Tobacco: May exacerbate gastroesophageal reflux; withdrawal can cause nausea
- Illicit drugs: Cocaine (mesenteric ischemia), amphetamines, opioid withdrawal
Social and Occupational History
- Food handling occupation: Increased exposure risk to enteric pathogens
- Healthcare workers: Exposure to norovirus and other infectious agents
- Recent travel: Traveler’s diarrhea, parasitic infections, hepatitis A
- Daycare or institutional exposure: Viral gastroenteritis outbreaks
- Occupational toxin exposure: Heavy metals, solvents, pesticides
Relevant Past Medical History
| Condition | Relevance to Vomiting |
|---|---|
| Diabetes mellitus | Gastroparesis (present in up to 50% of longstanding diabetes); diabetic ketoacidosis; autonomic neuropathy |
| Previous abdominal surgery | Adhesive small bowel obstruction (most common cause of small bowel obstruction in developed countries) |
| Migraine history | Abdominal migraine; cyclic vomiting syndrome (often considered migraine variant) |
| Psychiatric history | Psychogenic vomiting; eating disorders; anxiety-related nausea |
| Malignancy | Chemotherapy-induced; bowel obstruction from tumor; brain metastases; paraneoplastic gastroparesis |
| Chronic kidney disease | Uremic syndrome; medication accumulation; electrolyte disturbances |
| Thyroid disease | Hyperthyroidism can cause nausea and vomiting; associated with hyperemesis gravidarum |
| Connective tissue disorders | Scleroderma and other disorders can cause gastrointestinal dysmotility |
4. Physical Examination
A systematic head-to-toe approach for vomiting
Systematic Framework: Use the “Head to Extremities” approach for complete examination of patients presenting with vomiting. The examination serves three purposes: (1) assess severity and complications, (2) identify the underlying cause, and (3) detect conditions requiring urgent intervention.
General Inspection
- Overall appearance: Well or unwell? Alert or lethargic? Signs of distress?
- Nutritional status: Cachexia suggesting malignancy or chronic illness; obesity as risk factor for gastroesophageal reflux disease
- Hydration status: Dry mucous membranes, decreased skin turgor, sunken eyes
- Level of consciousness: Altered mentation may indicate metabolic derangement, sepsis, or intracranial pathology
- Posture and behavior: Lying still (peritonitis) versus restless (colic); compulsive hot bathing history (cannabinoid hyperemesis)
- Odors: Ketotic breath (diabetic ketoacidosis), uremic fetor (renal failure), feculent breath (obstruction)
Vital Signs
| Vital Sign | What to Look For | Clinical Significance |
|---|---|---|
| Temperature | Fever (greater than 38°C) or hypothermia | Fever suggests infection (gastroenteritis, cholecystitis, appendicitis, meningitis); hypothermia may indicate sepsis or severe metabolic derangement |
| Heart Rate | Tachycardia (greater than 100 beats per minute); bradycardia | Tachycardia indicates dehydration, pain, infection, or cardiac event; bradycardia with vomiting suggests increased intracranial pressure (Cushing reflex) |
| Blood Pressure | Hypotension; orthostatic changes (drop greater than 20 mmHg systolic on standing) | Hypotension indicates significant volume depletion, sepsis, or adrenal crisis; check orthostatic vitals in ambulatory patients |
| Respiratory Rate | Tachypnea; Kussmaul respirations (deep, rapid breathing) | Kussmaul breathing suggests metabolic acidosis (diabetic ketoacidosis); tachypnea may indicate compensation for metabolic alkalosis or primary respiratory pathology |
| Oxygen Saturation | Hypoxia (less than 94% on room air) | May indicate aspiration pneumonia, pulmonary embolism, or underlying cardiopulmonary disease |
| Blood Glucose | Hypoglycemia or marked hyperglycemia | Hyperglycemia with vomiting suggests diabetic ketoacidosis; hypoglycemia can cause nausea and requires urgent treatment |
Head, Eyes, Ears, Nose, Throat, and Neck
Head and Eyes
Pupil examination: Asymmetric pupils or sluggish response suggest intracranial pathology
Fundoscopy: Papilledema indicates increased intracranial pressure
Scleral icterus: Jaundice suggests hepatobiliary disease
Conjunctival pallor: Anemia from chronic blood loss or malnutrition
Ears, Nose, Throat, and Neck
Tympanic membranes: Middle ear pathology can cause vertigo and vomiting
Oral mucosa: Dry membranes indicate dehydration; dental erosions suggest chronic vomiting (bulimia)
Neck stiffness: Meningismus suggests meningitis or subarachnoid hemorrhage
Thyroid: Enlargement or nodules; hyperthyroidism associated with vomiting
Lymphadenopathy: May suggest infection or malignancy
Neurological Examination
| Component | Findings to Assess | Significance |
|---|---|---|
| Mental status | Level of consciousness, orientation, confusion | Altered consciousness suggests metabolic derangement, intoxication, or central nervous system pathology |
| Cranial nerves | Pupillary responses, eye movements, facial symmetry | Abnormalities suggest intracranial lesion; sixth nerve palsy indicates increased intracranial pressure |
| Nystagmus | Direction, characteristics (horizontal, vertical, rotatory) | Peripheral vestibular (horizontal, suppressed by fixation) versus central (vertical, direction-changing, not suppressed) |
| Cerebellar signs | Ataxia, dysmetria, dysdiadochokinesia | Posterior fossa lesion, cerebellar stroke, Wernicke encephalopathy |
| Motor and sensory | Focal weakness, sensory deficits | Stroke, intracranial mass, or other focal central nervous system pathology |
Cardiovascular Examination
- Jugular venous pressure: Elevated in heart failure, pericardial disease; low in dehydration
- Heart sounds: Third heart sound (heart failure), murmurs, pericardial rub
- Peripheral pulses: Assess volume and regularity; tachyarrhythmias can cause nausea
- Peripheral edema: Heart failure, nephrotic syndrome, liver disease
- Capillary refill: Prolonged refill (greater than 2 seconds) indicates poor perfusion
Abdominal Examination
Inspection
- Distension: Generalized (obstruction, ascites) or localized (mass, organomegaly)
- Visible peristalsis: Laddering pattern suggests small bowel obstruction
- Surgical scars: Previous surgery increases risk of adhesive obstruction
- Hernias: Check inguinal, umbilical, and incisional sites for incarceration
- Skin changes: Cullen sign (periumbilical bruising) or Grey Turner sign (flank bruising) suggest hemorrhagic pancreatitis
Auscultation
| Finding | Description | Conditions |
|---|---|---|
| High-pitched, hyperactive bowel sounds | Tinkling, rushing sounds with audible borborygmi | Early mechanical small bowel obstruction, gastroenteritis |
| Absent or hypoactive bowel sounds | Minimal or no sounds over 2-3 minutes of listening | Paralytic ileus, late obstruction, peritonitis |
| Succussion splash | Audible splash when shaking patient’s abdomen (patient supine) | Gastric outlet obstruction, gastroparesis (positive if heard more than 3 hours after eating) |
| Bruits | Vascular sounds over abdominal vessels | Renovascular disease, aortic aneurysm, mesenteric ischemia |
Percussion
- Tympany: Increased tympany suggests bowel distension with gas (obstruction, ileus)
- Dullness: Shifting dullness indicates ascites; fixed dullness suggests mass or organomegaly
- Liver span: Enlarged liver may indicate hepatic congestion, hepatitis, or malignancy
Palpation
- Tenderness location: Right upper quadrant (biliary), epigastric (gastric, pancreatic), right lower quadrant (appendicitis), left lower quadrant (diverticulitis)
- Peritoneal signs: Guarding, rigidity, rebound tenderness indicate peritoneal inflammation
- Murphy sign: Inspiratory arrest with right upper quadrant palpation suggests acute cholecystitis
- Masses: Palpable masses may indicate tumor, abscess, or organomegaly
- Hernial orifices: Always examine inguinal and femoral regions for incarcerated hernias
Rectal Examination
- Stool presence: Empty rectum with obstipation suggests complete obstruction
- Stool character: Melena indicates upper gastrointestinal bleeding; hematochezia suggests lower source or massive upper bleeding
- Masses: Rectal mass may indicate colorectal malignancy
- Prostatic tenderness: In males, tenderness suggests prostatitis
- Fecal impaction: Can cause overflow vomiting, especially in elderly patients
Expected Findings by Etiology
| Condition | General/Vitals | Abdominal | Other Key Findings |
|---|---|---|---|
| Acute gastroenteritis | May have fever, tachycardia if dehydrated | Mild diffuse tenderness, hyperactive bowel sounds | Often unremarkable; dry mucous membranes if dehydrated |
| Small bowel obstruction | Tachycardia, may be febrile if strangulated | Distension, high-pitched bowel sounds early, tenderness, visible peristalsis, surgical scars | Hernial orifices must be examined; empty rectum |
| Acute pancreatitis | Tachycardia, fever, may be hypotensive | Epigastric tenderness with guarding, decreased bowel sounds, Grey Turner or Cullen signs (severe) | Jaundice if biliary etiology; respiratory distress in severe cases |
| Acute cholecystitis | Fever, tachycardia | Right upper quadrant tenderness, positive Murphy sign, guarding | Jaundice suggests choledocholithiasis; palpable gallbladder (Courvoisier sign) suggests malignancy |
| Gastroparesis | Usually normal vitals | Epigastric fullness, succussion splash, mild tenderness | Stigmata of diabetes; often unremarkable examination |
| Increased intracranial pressure | Bradycardia, hypertension, irregular respirations (Cushing triad) | Usually unremarkable | Papilledema, sixth nerve palsy, altered consciousness, focal neurological signs |
| Vestibular disorder | Normal vitals | Unremarkable | Nystagmus (horizontal in peripheral, may be vertical in central), positive head impulse test (peripheral), abnormal Romberg |
| Diabetic ketoacidosis | Tachycardia, Kussmaul breathing, hypotension if severe | May have diffuse tenderness (sterile peritonitis) | Ketotic breath, altered consciousness, dry mucous membranes, poor skin turgor |
| Acute myocardial infarction | Variable; may have hypotension, bradycardia, or tachycardia | Usually unremarkable | Diaphoresis, pallor, elevated jugular venous pressure, new murmur, third heart sound |
| Cannabinoid hyperemesis syndrome | Usually normal; may have mild tachycardia | Mild epigastric tenderness or unremarkable | Often unremarkable; patient may report relief with hot bathing; red eyes from chronic cannabis use |
Important Teaching Point
Normal examination is common! Many significant causes of vomiting present with entirely normal or near-normal physical examination findings. These include:
- Early pregnancy
- Medication-induced nausea and vomiting
- Early gastroparesis
- Cyclic vomiting syndrome (between episodes)
- Psychogenic vomiting
- Metabolic causes (early diabetic ketoacidosis, hypercalcemia, uremia)
- Inferior myocardial infarction (abdominal examination often normal)
A normal physical examination does not exclude serious pathology. Clinical suspicion based on history should guide further investigation even when examination findings are unremarkable.
Special Examination Maneuvers
| Test | Technique | Positive Finding Indicates |
|---|---|---|
| Murphy sign | Palpate right upper quadrant and ask patient to inspire deeply | Inspiratory arrest due to pain suggests acute cholecystitis |
| Rovsing sign | Palpate left lower quadrant deeply | Pain referred to right lower quadrant suggests appendicitis |
| Carnett sign | Palpate area of tenderness, then have patient tense abdominal muscles (head raise) | Increased pain suggests abdominal wall pathology; decreased suggests intra-abdominal cause |
| Head impulse test | Rapid head rotation while patient fixates on examiner’s nose | Corrective saccade indicates peripheral vestibular lesion (vestibular neuritis) |
| Dix-Hallpike maneuver | Rapid movement from sitting to supine with head turned and extended | Delayed rotatory nystagmus suggests benign paroxysmal positional vertigo |
5. Differential Diagnosis
Systematic approach organized by probability and clinical features
Acute Vomiting (Duration: Less than 1 week)
| Probability | Condition | Key Features | Red Flags |
|---|---|---|---|
| COMMON (approximately 70%) | Acute viral gastroenteritis | Acute onset, diarrhea, sick contacts, self-limiting over 24-72 hours | Severe dehydration, bloody diarrhea, high fever |
| Food poisoning | Onset within hours of eating contaminated food, others affected, short duration | Neurological symptoms (botulism), bloody stool | |
| Medication-induced | Temporal relationship to new medication or dose increase | Digoxin toxicity signs, serotonin syndrome | |
| Acute gastritis | Epigastric discomfort, nonsteroidal anti-inflammatory drug or alcohol use | Hematemesis, melena, severe pain | |
| Motion sickness | Clear relationship to motion, vertigo, improves when motion stops | Symptoms persist after motion ceases | |
| LESS COMMON (approximately 20%) | Acute cholecystitis | Right upper quadrant pain, fever, Murphy sign positive, fatty food trigger | Jaundice, peritoneal signs, sepsis |
| Acute pancreatitis | Severe epigastric pain radiating to back, alcohol or gallstone history | Hypotension, respiratory distress, Cullen/Grey Turner signs | |
| Small bowel obstruction | Colicky pain, distension, obstipation, prior abdominal surgery | Fever, peritoneal signs (strangulation), feculent vomiting | |
| Acute appendicitis | Periumbilical pain migrating to right lower quadrant, anorexia, low-grade fever | Peritoneal signs, high fever (perforation) | |
| Vestibular neuritis/labyrinthitis | Severe vertigo, nystagmus, worse with head movement, often post-viral | Focal neurological signs, vertical nystagmus | |
| UNCOMMON BUT SERIOUS (approximately 10%) | Acute myocardial infarction | Chest discomfort, diaphoresis, dyspnea, risk factors; inferior wall often presents with nausea | Hypotension, arrhythmia, altered consciousness |
| Diabetic ketoacidosis | Known diabetes, polyuria, polydipsia, abdominal pain, Kussmaul breathing | Altered consciousness, severe dehydration | |
| Meningitis | Headache, fever, neck stiffness, photophobia | Petechial rash, altered consciousness, seizures | |
| Subarachnoid hemorrhage | Sudden severe headache (“thunderclap”), neck stiffness | Altered consciousness, focal neurological signs | |
| Adrenal crisis | Known adrenal insufficiency or steroid use, hypotension, weakness | Shock, hypoglycemia, altered consciousness | |
| Ectopic pregnancy | Reproductive-age female, missed period, pelvic pain | Hypotension, peritoneal signs (rupture) |
Persistent Vomiting (Duration: 1 to 4 weeks)
Step-by-Step Approach to Persistent Vomiting:
- Step 1: Rule out pregnancy in reproductive-age females
- Step 2: Review all medications for emetogenic potential
- Step 3: Consider mechanical obstruction (partial) or gastroparesis
- Step 4: Evaluate for metabolic and endocrine causes
- Step 5: Consider intracranial pathology if neurological symptoms present
| Probability | Condition | Approximate Frequency | Key Distinguishing Features |
|---|---|---|---|
| COMMON | Pregnancy (first trimester) | Up to 80% of pregnancies | Morning predominance, food aversions, amenorrhea, positive pregnancy test |
| Medication-induced (ongoing) | 20% of patients on emetogenic drugs | Temporal relationship to medication, improves with discontinuation | |
| Post-infectious gastroparesis | Variable | Follows viral illness, early satiety, bloating, delayed gastric emptying on testing | |
| Peptic ulcer disease | 10-15% of persistent cases | Epigastric pain, meal-related symptoms, Helicobacter pylori or NSAID exposure | |
| LESS COMMON | Partial small bowel obstruction | 5-10% | Intermittent colicky pain, prior surgery, symptoms worsen with eating |
| Hyperemesis gravidarum | 0.5-2% of pregnancies | Severe persistent vomiting, weight loss greater than 5%, ketonuria, requires hospitalization | |
| Hypercalcemia | Variable | Constipation, polyuria, confusion, bone pain, malignancy or hyperparathyroidism | |
| UNCOMMON | Intracranial mass or hydrocephalus | Rare but serious | Morning headache, projectile vomiting, papilledema, focal neurological signs |
| Addison disease | Rare | Weight loss, fatigue, hyperpigmentation, hypotension, hyponatremia | |
| Superior mesenteric artery syndrome | Rare | Recent significant weight loss, postprandial vomiting relieved by prone or left lateral position |
Chronic Vomiting (Duration: Greater than 4 weeks)
Step-by-Step Approach to Chronic Vomiting:
- Step 1: Exclude mechanical obstruction with upper endoscopy and/or imaging
- Step 2: Assess for gastroparesis with gastric emptying study
- Step 3: Evaluate for rumination syndrome and cyclic vomiting syndrome based on history
- Step 4: Consider functional nausea and vomiting if structural and motility testing normal
- Step 5: Screen for psychiatric comorbidity and eating disorders
| Probability | Condition | Approximate Frequency | Key Distinguishing Features |
|---|---|---|---|
| COMMON | Gastroparesis | 25-35% of chronic cases | Early satiety, postprandial fullness, bloating, delayed emptying on scintigraphy; diabetes, post-surgical, or idiopathic |
| Cyclic vomiting syndrome | 15-20% | Stereotypical episodes lasting hours to days, symptom-free intervals, migraine history, triggers identifiable | |
| Cannabinoid hyperemesis syndrome | Increasing prevalence | Chronic cannabis use, compulsive hot bathing provides relief, cyclic pattern | |
| Functional nausea and vomiting | 20-30% | Normal investigations, often stress-related, no weight loss despite symptoms | |
| LESS COMMON | Rumination syndrome | 5-10% | Effortless regurgitation within minutes of eating, re-chewing or spitting, not preceded by nausea |
| Eating disorders (bulimia nervosa) | Variable | Self-induced vomiting, binge eating, body image disturbance, dental erosions, Russell sign | |
| Chronic intestinal pseudo-obstruction | Rare | Recurrent obstructive symptoms without mechanical cause, often with other motility disorders | |
| Gastric outlet obstruction | 5% | Undigested food vomited hours after meals, succussion splash, weight loss; peptic ulcer or malignancy | |
| UNCOMMON | Gastric or esophageal malignancy | 2-5% | Weight loss, dysphagia, early satiety, anemia, age greater than 55 with new symptoms |
| Chronic mesenteric ischemia | Rare | Postprandial pain (“intestinal angina”), food fear, weight loss, vascular disease elsewhere | |
| Central nervous system pathology | Rare | Headache, neurological symptoms, posterior fossa lesions, demyelinating disease |
Anatomical Approach to Vomiting
Central Nervous System
Increased intracranial pressure
Migraine
Meningitis/encephalitis
Vestibular disorders
Posterior fossa tumors
Hydrocephalus
Subarachnoid hemorrhage
Gastrointestinal Tract
Gastroenteritis
Gastroparesis
Bowel obstruction
Peptic ulcer disease
Pancreatitis
Cholecystitis
Appendicitis
Gastric malignancy
Metabolic and Endocrine
Diabetic ketoacidosis
Uremia
Hypercalcemia
Hyponatremia
Adrenal insufficiency
Hyperthyroidism
Pregnancy
Other Causes
Medications and toxins
Myocardial infarction
Cyclic vomiting syndrome
Cannabinoid hyperemesis
Psychogenic vomiting
Eating disorders
Postoperative
Drug-Induced Vomiting
| Drug or Drug Class | Mechanism | Characteristics | Time to Resolution After Stopping |
|---|---|---|---|
| Opioid analgesics | Chemoreceptor trigger zone stimulation via opioid receptors; delayed gastric emptying | Onset within days of starting; often worse with movement; constipation common | Tolerance often develops within 5-7 days; otherwise 1-2 days after stopping |
| Chemotherapy agents | Serotonin release from gut enterochromaffin cells; direct chemoreceptor trigger zone stimulation | Acute (within 24 hours) and delayed (days 2-5) phases; severity varies by agent | Acute phase: 24-48 hours; delayed phase: up to 7 days |
| Nonsteroidal anti-inflammatory drugs | Gastric mucosal irritation; prostaglandin inhibition | Dyspepsia, epigastric pain; may cause gastritis or ulceration | Days to weeks depending on mucosal damage |
| Antibiotics (macrolides, metronidazole) | Erythromycin acts as motilin agonist; metronidazole causes metallic taste and nausea | Dose-related; gastrointestinal upset common | 24-48 hours after completion |
| Digoxin | Direct chemoreceptor trigger zone stimulation | May indicate toxicity; associated with visual changes, arrhythmias | Days (depending on renal function); may require digoxin-specific antibody |
| Selective serotonin reuptake inhibitors | Increased serotonergic activity in gut and central nervous system | Usually early in treatment; often improves with continued use | 1-2 weeks; tolerance often develops |
| Dopamine agonists (levodopa, pramipexole) | Dopamine receptor stimulation at chemoreceptor trigger zone | Common in Parkinson disease treatment; dose-related | Days; may require domperidone for ongoing treatment |
| Iron supplements | Direct gastric mucosal irritation | Dose-related; improved by taking with food or reducing dose | Immediate upon stopping or dose reduction |
| Theophylline | Chemoreceptor trigger zone stimulation; phosphodiesterase inhibition | Dose-related; may indicate toxicity; check serum levels | 24-48 hours depending on formulation |
| Oral contraceptives | Estrogen-mediated effect similar to pregnancy | Usually improves after first few cycles | Usually within first cycle after stopping |
| Colchicine | Gastrointestinal toxicity affecting rapidly dividing cells | Diarrhea often accompanies; may indicate toxicity | 24-48 hours; dose reduction usually required |
Quick Reference: “If You See This, Think This”
| Clinical Clue | Think This First | Next Step |
|---|---|---|
| Projectile vomiting without nausea | Increased intracranial pressure | Urgent neuroimaging (CT head) |
| Feculent vomiting | Distal small bowel or colonic obstruction | Abdominal X-ray, CT abdomen, surgical consultation |
| Relief with hot bathing | Cannabinoid hyperemesis syndrome | Detailed substance use history, cannabis cessation |
| Vomiting undigested food hours after eating | Gastroparesis or gastric outlet obstruction | Upper endoscopy, gastric emptying study |
| Stereotypical episodes with symptom-free intervals | Cyclic vomiting syndrome | Detailed pattern history, migraine history, rule out metabolic causes |
| Morning vomiting in reproductive-age female | Pregnancy | Urine or serum pregnancy test |
| Vomiting with severe headache | Migraine, subarachnoid hemorrhage, meningitis | CT head, lumbar puncture if indicated |
| Vomiting with vertigo | Vestibular disorder (peripheral or central) | Neurological examination, head impulse test, consider MRI |
| Diabetic with vomiting and abdominal pain | Diabetic ketoacidosis | Stat glucose, ketones, arterial blood gas, basic metabolic panel |
| Vomiting with diaphoresis and chest discomfort | Acute myocardial infarction | ECG, troponin, immediate cardiology consultation |
| Recent abdominal surgery with vomiting | Adhesive small bowel obstruction | Abdominal X-ray, CT abdomen, surgical consultation |
| Effortless regurgitation without nausea | Rumination syndrome | Detailed history, high-resolution esophageal manometry |
6. Diagnostic Investigations
A stepwise, cost-effective approach guided by clinical suspicion
Baseline Investigations for All Patients with Significant Vomiting
| Investigation | Purpose | What to Look For | Practical Points |
|---|---|---|---|
| Basic metabolic panel (electrolytes, creatinine, glucose) | Assess metabolic consequences and identify metabolic causes | Hypokalemia, hypochloremia, metabolic alkalosis (from acid loss); elevated creatinine (dehydration or renal cause); hyperglycemia (diabetic ketoacidosis) | Essential in any patient with more than mild vomiting; guides fluid and electrolyte replacement |
| Complete blood count | Assess for infection, anemia, hemoconcentration | Leukocytosis (infection, inflammation); anemia (chronic blood loss, malignancy); elevated hematocrit (dehydration) | Leukocytosis with left shift suggests bacterial infection or inflammation |
| Liver function tests | Screen for hepatobiliary disease | Elevated transaminases (hepatitis); elevated alkaline phosphatase and bilirubin (biliary obstruction) | Particularly important if right upper quadrant pain or jaundice present |
| Lipase | Screen for acute pancreatitis | Elevation greater than 3 times upper limit of normal is diagnostic of acute pancreatitis | More specific than amylase; remains elevated longer |
| Urine pregnancy test | Exclude pregnancy in reproductive-age females | Positive result changes entire differential and management | Mandatory before any radiological investigations or certain medications |
| Urinalysis | Assess hydration, screen for urinary tract infection, detect ketones | Ketonuria (starvation ketosis, diabetic ketoacidosis); concentrated urine (dehydration); pyuria (urinary tract infection) | Specific gravity indicates hydration status |
Targeted Investigations by Suspected Etiology
If Suspecting Bowel Obstruction
First-Line Tests
- Abdominal X-ray (supine and erect): Air-fluid levels, dilated bowel loops (greater than 3 cm for small bowel, greater than 6 cm for colon); sensitivity approximately 70% for small bowel obstruction
- CT abdomen and pelvis with contrast: Gold standard; identifies site, cause, and complications (strangulation, perforation); sensitivity greater than 90%
Additional Tests
- Lactate level: Elevated lactate suggests bowel ischemia or strangulation; values greater than 2 mmol/L concerning
- Water-soluble contrast study: Can be diagnostic and therapeutic in partial small bowel obstruction; appearance in colon within 24 hours predicts resolution
If Suspecting Gastroparesis
First-Line Tests
- Upper gastrointestinal endoscopy: Exclude mechanical obstruction; may show retained food; rules out peptic ulcer disease and malignancy
- Gastric emptying scintigraphy: Gold standard for diagnosis; measures retention of radiolabeled solid meal at 1, 2, and 4 hours; retention greater than 10% at 4 hours is abnormal
Additional Tests
- Hemoglobin A1c: Assess glycemic control in diabetics (poor control worsens gastroparesis)
- Thyroid function tests: Both hypothyroidism and hyperthyroidism can affect gastric motility
- Wireless motility capsule: Alternative to scintigraphy; measures whole gut transit
If Suspecting Intracranial Pathology
First-Line Tests
- CT head without contrast: Rapid assessment for hemorrhage, mass effect, hydrocephalus; first-line in emergency setting
- MRI brain with gadolinium: Superior for posterior fossa lesions, small tumors, demyelinating disease; indicated if CT normal but clinical suspicion remains
Additional Tests
- Lumbar puncture: If meningitis suspected (after CT to exclude mass effect); measure opening pressure if idiopathic intracranial hypertension suspected
- CT or MR angiography: If subarachnoid hemorrhage suspected with negative CT; evaluate for aneurysm
If Suspecting Metabolic or Endocrine Cause
First-Line Tests
- Arterial or venous blood gas: Assess acid-base status; metabolic acidosis with elevated anion gap (diabetic ketoacidosis, uremia); metabolic alkalosis (prolonged vomiting)
- Serum calcium (corrected for albumin): Hypercalcemia causes nausea; greater than 3.0 mmol/L often symptomatic
- Thyroid function tests: Both hyperthyroidism and hypothyroidism can cause nausea and vomiting
Additional Tests
- Morning cortisol and ACTH stimulation test: If adrenal insufficiency suspected (hypotension, hyponatremia, hyperkalemia)
- Beta-hydroxybutyrate: More accurate than urine ketones for diabetic ketoacidosis
- Serum osmolality: Evaluate for hyperosmolar states
If Suspecting Vestibular Disorder
First-Line Tests
- Clinical examination: Head impulse test, Dix-Hallpike maneuver, nystagmus assessment often sufficient for diagnosis
- Audiometry: If Ménière disease suspected (fluctuating hearing loss)
Additional Tests
- MRI brain (posterior fossa protocol): If central cause suspected (vertical nystagmus, direction-changing nystagmus, negative head impulse test with nystagmus)
- Videonystagmography: Formal vestibular function testing if diagnosis unclear
If Suspecting Upper Gastrointestinal Bleeding
First-Line Tests
- Complete blood count: May be normal initially; serial measurements useful; hemoglobin may take 24-72 hours to reflect acute blood loss
- Coagulation studies (PT/INR, aPTT): Assess for coagulopathy; guide reversal if needed
- Type and screen/crossmatch: Prepare for potential transfusion
Urgent Investigation
- Upper gastrointestinal endoscopy: Both diagnostic and therapeutic; ideally within 24 hours for non-variceal bleeding, within 12 hours for variceal bleeding; identifies source in greater than 90% of cases
- Glasgow-Blatchford score: Risk stratification; score of 0 may allow outpatient management
If Suspecting Cyclic Vomiting Syndrome or Cannabinoid Hyperemesis Syndrome
Investigations (Primarily to Exclude Other Causes)
- Upper gastrointestinal endoscopy: Usually normal; excludes structural disease
- Gastric emptying study: Usually normal between episodes
- Metabolic panel and liver function tests: Exclude metabolic causes
Diagnostic Criteria (Clinical Diagnosis)
- Cyclic vomiting syndrome (Rome IV): Stereotypical episodes, 3 or more in 1 year, at least 1 week apart, absence of vomiting between episodes
- Cannabinoid hyperemesis: Chronic cannabis use, cyclical vomiting, relief with hot bathing, resolution with cannabis cessation
Stepwise Investigation Algorithm
Tier 1: All Patients with Significant Vomiting
- Basic metabolic panel, complete blood count, liver function tests, lipase
- Urine pregnancy test (reproductive-age females)
- Urinalysis
Tier 2: Based on Clinical Suspicion
- Abdominal imaging (X-ray, CT) — if obstruction or acute abdominal pathology suspected
- CT head — if intracranial pathology suspected
- ECG, troponin — if cardiac cause suspected
- Blood gas, calcium, thyroid function tests — if metabolic cause suspected
Tier 3: Chronic or Unexplained Vomiting
- Upper gastrointestinal endoscopy — exclude structural disease
- Gastric emptying study — assess for gastroparesis
- Consider specialist referral (gastroenterology, neurology) for further evaluation
Empiric Treatment Trials as Diagnostic Tools
Sequential Empiric Therapy Approach
When diagnosis is unclear and investigations are non-revealing, empiric treatment trials can serve as diagnostic tools. Response to therapy supports the diagnosis. This approach is particularly useful in chronic nausea and vomiting.
- Prokinetic trial (metoclopramide 10 mg before meals for 2-4 weeks): Response suggests gastroparesis or functional dyspepsia
- Proton pump inhibitor trial (omeprazole 20 mg twice daily for 4-8 weeks): Response suggests acid-related disorder (gastroesophageal reflux disease, peptic ulcer disease)
- Tricyclic antidepressant trial (amitriptyline 10-25 mg at bedtime, titrate slowly): Response suggests functional nausea and vomiting or visceral hypersensitivity
- Migraine prophylaxis trial (if cyclic pattern with migraine features): Response to topiramate, propranolol, or amitriptyline supports cyclic vomiting syndrome
Key Laboratory Value Interpretations in Vomiting
| Finding | Mechanism | Clinical Significance |
|---|---|---|
| Hypokalemia (K+ less than 3.5 mmol/L) | Direct loss in vomitus; renal wasting due to alkalosis and secondary hyperaldosteronism | May cause weakness, arrhythmias; requires replacement; severe hypokalemia (less than 2.5 mmol/L) is urgent |
| Hypochloremic metabolic alkalosis | Loss of gastric hydrochloric acid; chloride-responsive alkalosis | Classic finding in prolonged vomiting; corrected with volume and chloride replacement (normal saline) |
| Elevated blood urea nitrogen with normal creatinine | Prerenal azotemia from volume depletion; blood urea nitrogen/creatinine ratio greater than 20:1 | Indicates dehydration; responds to fluid resuscitation |
| Elevated blood urea nitrogen and creatinine (proportional) | Intrinsic renal disease or severe prerenal azotemia | May indicate uremia as cause of vomiting; requires nephrology input if severe |
| Elevated anion gap metabolic acidosis | Diabetic ketoacidosis, lactic acidosis, uremia, toxic ingestion | Urgent evaluation required; calculate anion gap (Na – Cl – HCO3; normal 8-12) |
| Lipase greater than 3 times upper limit of normal | Pancreatic acinar cell injury | Diagnostic of acute pancreatitis in appropriate clinical context |
7. Pattern Recognition and Clinical Decision-Making
Practical algorithms and decision pathways
Step 1: Is This Urgent?
| Clinical Scenario | Urgency Level | Immediate Action |
|---|---|---|
| Hematemesis with hemodynamic instability | EMERGENT | Resuscitate (2 large-bore IV lines, crystalloid, blood products), urgent endoscopy, ICU admission |
| Suspected bowel obstruction with peritoneal signs | EMERGENT | NPO, nasogastric decompression, IV fluids, stat surgical consultation, CT abdomen |
| Projectile vomiting with altered consciousness or focal neurological signs | EMERGENT | Stat CT head, neurosurgical consultation, elevate head of bed, manage intracranial pressure |
| Diabetic with vomiting, altered mental status, Kussmaul breathing | EMERGENT | Stat glucose, ketones, blood gas; begin insulin and IV fluids per diabetic ketoacidosis protocol |
| Vomiting with chest pain and diaphoresis | EMERGENT | Stat ECG, troponin, aspirin; activate cardiac catheterization if ST-elevation myocardial infarction |
| Severe headache with neck stiffness and vomiting | EMERGENT | CT head, lumbar puncture if CT negative; empiric antibiotics if meningitis suspected |
| Signs of severe dehydration (hypotension, tachycardia, oliguria) | URGENT | IV fluid resuscitation, electrolyte replacement, identify and treat underlying cause |
| Bilious vomiting with abdominal distension | URGENT | Abdominal X-ray, CT if obstruction suspected, surgical consultation |
| Pregnant patient with severe vomiting unable to tolerate oral intake | URGENT | IV fluids, antiemetics safe in pregnancy, check electrolytes, assess for hyperemesis gravidarum |
| Vomiting with vertigo and nystagmus | URGENT | Distinguish peripheral from central cause (HINTS examination); MRI if central features present |
| Self-limiting vomiting with mild dehydration, tolerating oral fluids | ROUTINE | Oral rehydration, antiemetics as needed, safety net advice, follow-up if symptoms persist |
| Chronic intermittent vomiting, stable, no red flags | ROUTINE | Outpatient investigation with upper endoscopy, gastric emptying study as appropriate |
Step 2: Classify by Duration and Direct to Appropriate Pathway
Acute (Less than 1 week)
Focus: Identify emergencies, assess hydration, symptomatic management
Proceed to: Algorithm A
Persistent (1-4 weeks)
Focus: Rule out pregnancy, review medications, consider structural causes
Proceed to: Algorithm B
Chronic (Greater than 4 weeks)
Focus: Systematic investigation, consider motility disorders, functional causes
Proceed to: Algorithm C
Step 3: Follow the Appropriate Algorithm
Algorithm A: Acute Vomiting
| Clinical Scenario | Most Likely Diagnosis | Action |
|---|---|---|
| Acute onset with diarrhea, sick contacts, self-limiting | Acute viral gastroenteritis | Supportive care, oral rehydration, antiemetics PRN; investigate only if severe or prolonged |
| Onset within hours of meal, others affected who ate same food | Food poisoning | Supportive care; stool culture if bloody diarrhea or prolonged symptoms; report if outbreak suspected |
| New medication in past 1-2 weeks, no other symptoms | Medication-induced | Review medication list; consider dose reduction, alternative agent, or antiemetic cover |
| Right upper quadrant pain, fever, Murphy sign positive | Acute cholecystitis | NPO, IV fluids, analgesia, antibiotics, urgent ultrasound, surgical consultation |
| Severe epigastric pain radiating to back, elevated lipase | Acute pancreatitis | NPO, aggressive IV fluids, analgesia, monitor for complications, CT if diagnosis uncertain |
| Colicky abdominal pain, distension, prior abdominal surgery | Small bowel obstruction | NPO, nasogastric tube, IV fluids, CT abdomen, surgical consultation |
| Vertigo, nystagmus, recent viral illness, no focal neurological signs | Vestibular neuritis | Antiemetics, vestibular suppressants short-term, early mobilization, vestibular rehabilitation |
| Morning vomiting, amenorrhea, reproductive-age female | Early pregnancy | Confirm with pregnancy test; reassurance, dietary modifications, ginger, vitamin B6 |
Algorithm B: Persistent Vomiting (1-4 weeks)
| Clinical Scenario | Most Likely Diagnosis | Action |
|---|---|---|
| Positive pregnancy test, intractable vomiting, weight loss, ketonuria | Hyperemesis gravidarum | Hospital admission, IV fluids, thiamine before dextrose, antiemetics, electrolyte monitoring |
| Known diabetic, early satiety, bloating, undigested food in vomitus | Diabetic gastroparesis | Optimize glycemic control, dietary modifications, prokinetics, upper endoscopy to exclude obstruction |
| Intermittent symptoms, weight loss, prior abdominal surgery | Partial small bowel obstruction | CT abdomen, surgical consultation, may need operative intervention |
| Epigastric pain, relief with eating (duodenal) or worse with eating (gastric), NSAID use | Peptic ulcer disease | Upper endoscopy, test for Helicobacter pylori, proton pump inhibitor therapy |
| Fatigue, hypotension, hyponatremia, hyperpigmentation | Adrenal insufficiency | Morning cortisol, ACTH stimulation test, hydrocortisone if crisis suspected |
Algorithm C: Chronic Vomiting (Greater than 4 weeks)
| Clinical Scenario | Most Likely Diagnosis | Action |
|---|---|---|
| Early satiety, bloating, delayed gastric emptying on scintigraphy | Gastroparesis | Dietary modifications (small, low-fat, low-fiber meals), prokinetics, consider gastric electrical stimulation if refractory |
| Stereotypical episodes, symptom-free intervals, migraine history | Cyclic vomiting syndrome | Abortive therapy (triptans, ondansetron) at onset; prophylaxis (amitriptyline, topiramate) if frequent |
| Chronic cannabis use, compulsive hot bathing provides relief | Cannabinoid hyperemesis syndrome | Cannabis cessation (curative); capsaicin cream for acute episodes; traditional antiemetics often ineffective |
| Effortless regurgitation within minutes of eating, no nausea, no weight loss | Rumination syndrome | Diaphragmatic breathing exercises, behavioral therapy, baclofen may help |
| Normal investigations, stress-related, able to eat after vomiting | Functional nausea and vomiting | Reassurance, low-dose tricyclic antidepressants, consider psychological therapy |
| Binge eating, self-induced vomiting, body image concerns, dental erosions | Bulimia nervosa | Psychiatric referral, cognitive behavioral therapy, nutritional rehabilitation |
| Weight loss, dysphagia, anemia, age greater than 55 | Gastric or esophageal malignancy | Urgent upper endoscopy with biopsies, CT staging if malignancy confirmed |
“What Do I Do If…” Decision Reference
| Clinical Situation | Immediate Action | Next Step |
|---|---|---|
| Patient cannot tolerate any oral intake | IV access, fluid resuscitation with normal saline, IV antiemetics | Identify cause; consider admission if unable to maintain hydration |
| Patient is taking an ACE inhibitor and has chronic cough with vomiting | Consider if cough-induced vomiting; ACE inhibitors rarely cause vomiting directly | Evaluate for other causes; switch to ARB if cough is problematic |
| Vomiting continues despite standard antiemetics | Try alternative antiemetic class (different mechanism) | Consider combination therapy; investigate for structural cause |
| Patient requests investigation but has clear viral gastroenteritis | Reassure; explain self-limiting nature and typical 48-72 hour course | Safety net: return if symptoms persist beyond 5-7 days, bloody stool, or signs of dehydration |
| Elderly patient with new-onset vomiting and confusion | Broad workup: metabolic panel, complete blood count, urinalysis, chest X-ray | Consider CT head; high suspicion for serious pathology in this population |
| Post-surgical patient with vomiting on day 3-5 | Assess for ileus versus mechanical obstruction; examine for distension, bowel sounds | Abdominal X-ray; if obstruction suspected, CT and surgical consultation |
| Patient insists cannabis helps their nausea but has cyclic vomiting | Take detailed cannabis use history; explain cannabinoid hyperemesis syndrome | Trial of cannabis cessation for at least 1-2 weeks to assess; this is diagnostic and therapeutic |
| Chemotherapy patient with breakthrough vomiting despite prophylaxis | Add rescue antiemetic from different class; ensure adequate hydration | Review prophylaxis regimen for next cycle; consider adding NK1 antagonist or olanzapine |
Antiemetic Selection by Mechanism
| Suspected Mechanism/Cause | First-Line Antiemetic | Alternative Options |
|---|---|---|
| Gastroenteritis, chemotherapy (acute), postoperative | Ondansetron (5-HT3 antagonist) | Granisetron, dolasetron |
| Gastroparesis, functional dyspepsia | Metoclopramide (D2 antagonist + prokinetic) | Domperidone (if available), erythromycin (short-term) |
| Motion sickness, vestibular disorders | Promethazine or dimenhydrinate (H1 antagonists) | Scopolamine patch (anticholinergic), meclizine |
| Chemotherapy (delayed phase), refractory nausea | Aprepitant (NK1 antagonist) | Fosaprepitant, rolapitant; add dexamethasone |
| Opioid-induced | Ondansetron or prochlorperazine | Metoclopramide; tolerance often develops within days |
| Pregnancy (first trimester) | Vitamin B6 (pyridoxine) +/- doxylamine | Ondansetron (second line), metoclopramide, promethazine |
| Increased intracranial pressure | Dexamethasone (reduces edema) | Ondansetron for symptomatic relief; treat underlying cause |
| Anticipatory nausea, functional nausea | Lorazepam (benzodiazepine) | Low-dose tricyclic antidepressant, mirtazapine |
| Cannabinoid hyperemesis syndrome | Topical capsaicin (to abdomen) | Haloperidol; traditional antiemetics often ineffective; cannabis cessation is curative |
Troubleshooting Refractory Vomiting
Ask These Questions When Vomiting Persists Despite Treatment
- Is the diagnosis correct? Reconsider the differential; have key diagnoses been excluded?
- Are there multiple overlapping causes? Gastroparesis plus gastroesophageal reflux disease, medication effect plus underlying disease
- Is the antiemetic targeting the right pathway? Match antiemetic mechanism to presumed cause
- Has medication compliance been adequate? Verify dosing and timing
- Is the patient still using cannabis? Cannabinoid hyperemesis will not resolve without cessation
- Are there psychological factors? Anxiety, depression, and eating disorders can perpetuate symptoms
- Has there been adequate time for treatment response? Some treatments (tricyclics, prokinetics) require weeks to work
- Is specialist referral indicated? Gastroenterology, neurology, or psychiatry input may be needed
8. Clinical Pearls and Pitfalls
Practical wisdom — learn from successes and avoid common mistakes
Must-Know Clinical Pearls
Always check pregnancy status: In any reproductive-age female with vomiting, a pregnancy test is mandatory before further investigation or treatment. Pregnancy is a common and easily missed cause.
Inferior myocardial infarction presents with nausea: Up to 40% of inferior wall myocardial infarctions present with prominent nausea and vomiting due to vagal activation. Always consider cardiac causes in at-risk patients, even without chest pain.
Ask about cannabis use in every patient with unexplained cyclic vomiting: Cannabinoid hyperemesis syndrome is increasingly common and frequently misdiagnosed. The pathognomonic clue is relief with hot bathing.
Match antiemetic to mechanism: Ondansetron works well for gastrointestinal causes but poorly for motion sickness. Antihistamines work for vestibular causes but not for chemotherapy-induced vomiting. Understand the pathways.
The succussion splash is underused: A positive succussion splash (audible splash when shaking the abdomen) more than 3 hours after eating suggests gastric outlet obstruction or severe gastroparesis. It takes seconds to perform.
Examine the hernial orifices: An incarcerated inguinal or femoral hernia causing small bowel obstruction can be missed if the groin is not examined. This is a common and avoidable error.
Projectile vomiting without nausea is a red flag: This pattern, especially with headache or in the morning, suggests increased intracranial pressure. It requires urgent neuroimaging.
Give thiamine before glucose in malnourished patients: In patients with prolonged vomiting and malnutrition, giving glucose before thiamine can precipitate Wernicke encephalopathy. Always give thiamine first.
Critical Pitfalls to Avoid
Attributing vomiting to “gastritis” without investigation: “Gastritis” has become a wastebasket diagnosis. Do not label unexplained vomiting as gastritis without at least considering the broad differential and appropriate investigation.
Missing surgical emergencies: Bowel obstruction, appendicitis, and cholecystitis can present primarily with vomiting. Look for abdominal signs even when vomiting is the chief complaint.
Forgetting to review the medication list: Medications are one of the most common causes of vomiting. Always perform a thorough medication reconciliation, including recent changes and over-the-counter drugs.
Underestimating dehydration severity: Patients with prolonged vomiting can be significantly volume depleted even without obvious hypotension. Check orthostatic vital signs and assess mucous membranes carefully.
Overlooking electrolyte abnormalities: Hypokalemia from vomiting can be severe and cause cardiac arrhythmias. Check and replace electrolytes early, especially potassium and magnesium.
Dismissing “functional” vomiting without proper investigation: Functional nausea and vomiting is a diagnosis of exclusion. Ensure structural causes have been ruled out with appropriate testing before making this diagnosis.
Using metoclopramide long-term without monitoring: Metoclopramide can cause tardive dyskinesia with prolonged use. Limit duration to less than 12 weeks and use the lowest effective dose.
Assuming normal examination excludes serious pathology: Many serious causes of vomiting (myocardial infarction, diabetic ketoacidosis, early obstruction, intracranial pathology) can have minimal or no abdominal findings.
Key Takeaways
- Vomiting is a symptom, not a diagnosis — always seek the underlying cause rather than just treating symptoms.
- Duration guides the differential: acute vomiting is usually infectious or self-limiting; chronic vomiting requires systematic investigation.
- Red flags (hematemesis, feculent vomiting, projectile vomiting without nausea, severe abdominal pain, altered consciousness) require urgent evaluation.
- The vomiting reflex has four main input pathways (chemoreceptor trigger zone, vestibular system, gastrointestinal tract, cortical centers) — understanding these guides antiemetic selection.
- Always obtain a pregnancy test in reproductive-age females, a medication history in all patients, and a substance use history (especially cannabis) in those with cyclic patterns.
- Baseline investigations (metabolic panel, complete blood count, liver function tests, lipase, urinalysis) are indicated for any patient with more than mild vomiting.
- Physical examination should include vital signs (including orthostatic measurements), abdominal examination with hernial orifices, and neurological assessment when indicated.
- Metabolic alkalosis with hypokalemia is the classic laboratory finding in prolonged vomiting; correct with volume and chloride-containing fluids.
- Gastroparesis, cyclic vomiting syndrome, cannabinoid hyperemesis syndrome, and functional nausea and vomiting are the most common causes of chronic unexplained vomiting.
- Treatment should be targeted to the underlying cause; antiemetics provide symptomatic relief but do not address etiology.
Quick Reference Algorithm
Systematic Approach to the Vomiting Patient:
- Assess urgency: Check vital signs, identify red flags, determine if emergent intervention is needed.
- Characterize the vomiting: Determine duration (acute, persistent, chronic), character (bilious, bloody, feculent), and pattern (timing, triggers, associated symptoms).
- Take a focused history: Use the “VOMITS” mnemonic — Volume/Vomitus character, Onset/course, Meals/timing, Instigating factors, Treatments/toxins, Systemic review.
- Perform targeted examination: General inspection, vital signs with orthostatics, abdominal examination including hernial orifices, neurological examination if indicated.
- Obtain baseline investigations: Metabolic panel, complete blood count, liver function tests, lipase, pregnancy test (if applicable), urinalysis.
- Order targeted investigations based on clinical suspicion: Imaging, endoscopy, motility studies, or other specialized tests as indicated.
- Initiate appropriate treatment: Address fluid and electrolyte deficits, select antiemetics based on suspected mechanism, treat underlying cause.
- Establish follow-up plan: Define criteria for return, arrange outpatient investigation for chronic cases, ensure safety netting.
Common Scenarios at a Glance
| Scenario | Think | Do |
|---|---|---|
| Young adult with acute vomiting and diarrhea after party | Viral gastroenteritis or food poisoning | Supportive care, oral rehydration, antiemetics PRN |
| Diabetic with vomiting, abdominal pain, fruity breath | Diabetic ketoacidosis | Stat glucose, ketones, blood gas; begin DKA protocol |
| Elderly with new vomiting, constipation, prior surgery | Small bowel obstruction | Abdominal X-ray, CT abdomen, surgical consultation |
| Young woman with morning vomiting, missed period | Pregnancy | Pregnancy test first; then reassurance and supportive measures |
| Chronic vomiting with compulsive hot bathing behavior | Cannabinoid hyperemesis syndrome | Confirm cannabis use; advise cessation; capsaicin for acute relief |
| Post-cholecystectomy patient with vomiting, right upper quadrant pain | Retained common bile duct stone, bile leak | Liver function tests, ultrasound, consider MRCP or ERCP |
| Severe headache, vomiting, neck stiffness, fever | Meningitis | Urgent CT head, lumbar puncture, empiric antibiotics |
| Stereotypical vomiting episodes with migraine history | Cyclic vomiting syndrome | Abortive therapy at onset; prophylaxis if recurrent |