Vomiting evaluation
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Vomiting — Clinical Evaluation
Definition & Physiology
Vomiting is the forceful expulsion of gastric contents through the mouth, coordinated by the vomiting center in the medullary reticular formation. It proceeds through three sequential phases:
- Nausea — increased duodenal/jejunal tone, decreased gastric tone → intestinal contents reflux into stomach; associated with hypersalivation and tachycardia
- Retching — rhythmic, synchronous contraction of diaphragm, abdominal muscles, and intercostal muscles against a closed glottis, without expulsion
- Vomiting — contraction of external oblique and rectus abdominis + relaxation of hiatal diaphragm → increased thoracoabdominal pressure; simultaneous relaxation of gastric fundus, cardia, and upper esophageal sphincter; glottis closes to prevent aspiration
Figure: The vomiting center (medullary/pontine reticular formation) receives input from vagal and sympathetic afferents from the GI tract and from the chemoreceptor trigger zone (CTZ) in the area postrema. — Guyton & Hall Medical Physiology
Afferent Inputs to the Vomiting Center
| Source | Examples |
|---|---|
| GI visceral afferents (vagal/sympathetic) | Gastric distension, irritation, duodenal stimuli |
| Extra-GI visceral afferents | Biliary system, peritoneum, pharynx, genitalia, heart (e.g., MI) |
| CNS/cortical afferents | Vestibular system, thalamus, cerebral cortex |
| Chemoreceptor trigger zone (CTZ) | Area postrema, floor of 4th ventricle — partially outside the blood-brain barrier; responds to drugs (morphine, digoxin, apomorphine, chemotherapy), toxins, metabolic derangements |
The CTZ is rich in dopamine D2 and serotonin (5-HT3) receptors; the lateral vestibular nucleus is rich in cholinergic and histamine receptors — these are targets for antiemetic therapy.
History
Characterize the Vomiting
| Feature | Clinical significance |
|---|---|
| Timing/onset | Acute (<1 week) vs. chronic (>1 month) |
| Relationship to meals | Immediately post-prandial → gastric outlet obstruction or pyloric stenosis; early morning → pregnancy, raised ICP, uremia |
| Frequency and volume | Copious/frequent → obstruction |
| Effortless/projectile | Projectile without nausea → CNS etiology (raised ICP) |
| Relief with vomiting | Relieves pain in PUD and bowel obstruction; no relief in inflammatory conditions (cholecystitis, pancreatitis) |
Characteristics of the Vomitus
| Vomitus Appearance | Suggested Diagnosis |
|---|---|
| Bright red blood | Peptic ulcer, gastritis, esophageal varices, Mallory-Weiss tear, Dieulafoy lesion, aortoenteric fistula |
| Coffee-ground | Any upper GI bleed; Hgb → hematin via gastric acid; also iron tablets, red wine |
| Undigested food | Gastric outlet obstruction, achalasia, esophageal stricture/atresia |
| Bilious (yellow-green) | Obstruction distal to ampulla of Vater |
| Feculent (brown, fecal odor) | Advanced low small bowel or large bowel obstruction |
| True feces | Gastrocolic fistula |
Associated Symptoms
- Diarrhea + fever + myalgias → infectious gastroenteritis
- Headache + visual changes + neck stiffness → CNS etiology (meningitis, raised ICP, intracranial mass)
- Nystagmus + vertigo + tinnitus → vestibular/labyrinthine disease
- Abdominal pain → obstruction, PUD, cholecystitis, pancreatitis, appendicitis
- Chest pain → myocardial infarction (especially inferior MI), esophageal rupture
- Dysphagia → esophageal disease
- Jaundice → hepatobiliary disease
- Episodic with hot-shower relief + cannabis use → cannabinoid hyperemesis syndrome (CHS)
Differential Diagnosis by Category
GI Causes
- Gastroenteritis (most common, usually viral/self-limited)
- Peptic ulcer disease / gastritis
- Gastric outlet obstruction (pyloric stenosis, malignancy)
- Intestinal obstruction (adhesions, hernia, volvulus, intussusception)
- Acute cholecystitis, cholelithiasis
- Acute pancreatitis
- Hepatitis
- Achalasia / esophageal stricture
- Gastroparesis
Neurologic / CNS
- Meningitis
- Intracranial hypertension (tumor, hydrocephalus, hemorrhage)
- Migraine
- Labyrinthitis / vestibular neuritis / motion sickness
- Post-concussion syndrome
Metabolic / Endocrine
- Diabetic ketoacidosis
- Renal failure (uremia)
- Adrenal insufficiency
- Hyperparathyroidism / hypercalcemia
- Hypo/hyperthyroidism
Drugs & Toxins
- Opioids (morphine, codeine)
- Digoxin toxicity
- Chemotherapy
- NSAIDs
- Alcohol
Obstetric
- Pregnancy (hyperemesis gravidarum)
Cardiac
- Inferior/posterior myocardial infarction
Other
- Cyclical vomiting syndrome (CVS) — episodic, migraine-associated
- Cannabinoid hyperemesis syndrome (CHS)
- Psychogenic / bulimia nervosa
- Post-operative nausea and vomiting (PONV)
Age-Based Consideration (Pediatric)
| Age | Priority Diagnoses |
|---|---|
| Newborn | Esophageal/intestinal atresia, malrotation ± volvulus, Hirschsprung's, metabolic disorders, sepsis |
| Infant (<12 mo) | Pyloric stenosis, intussusception, GERD, UTI, meningitis |
| Child (>12 mo) | Gastroenteritis, intussusception, migraine, appendicitis, intracranial mass |
Bilious or bloody vomitus, hematochezia, or significant abdominal pain should trigger concern for diagnoses beyond simple viral gastroenteritis. — Tintinalli's Emergency Medicine
Physical Examination
| System | Finding | Suggested Diagnosis |
|---|---|---|
| General | Poor skin turgor, dry mucous membranes | Dehydration |
| Vital signs | Fever | Gastroenteritis, cholecystitis, appendicitis, peritonitis |
| Vital signs | Tachycardia + orthostatic changes | Dehydration/volume depletion |
| Eyes | Nystagmus | Labyrinthitis, vertebrobasilar insufficiency, cerebellar infarct/bleed, drug intoxication |
| Eyes | Papilledema | Raised ICP (CNS tumor, bleed) |
| Neck | Goiter | Thyroid disease |
| Lungs | Rales | Pneumonia |
| Abdomen | Distension, high-pitched bowel sounds | Obstruction |
| Abdomen | RUQ tenderness + Murphy's sign | Cholecystitis |
| Abdomen | Rigidity/guarding | Peritonitis, perforation |
| Oral | Loss of dental enamel | Bulimia nervosa |
Complications of Vomiting
- Metabolic alkalosis with hypochloremia and hypokalemia (from loss of H⁺ and Cl⁻)
- Dehydration and electrolyte disturbances
- Mallory-Weiss tear — mucosal laceration at gastroesophageal junction from violent retching
- Boerhaave syndrome — full-thickness esophageal rupture → mediastinitis/peritonitis (life-threatening)
- Aspiration pneumonitis — in patients with impaired consciousness
- Malnutrition / weight loss
- Wernicke encephalopathy — in prolonged vomiting (thiamine depletion)
- Bezoar formation in severe gastroparesis
Diagnostic Workup
Guided by history and physical; no single test is universally indicated.
| Test | Indication |
|---|---|
| BMP/electrolytes, BUN, Cr | Assess dehydration, metabolic alkalosis, renal failure |
| CBC | Infection, anemia |
| LFTs, lipase | Biliary/pancreatic disease |
| Urine hCG | Any woman of reproductive age |
| Urinalysis | UTI, renal disease |
| Blood glucose | DKA |
| Upright CXR / AXR | Free air (perforation), obstruction (air-fluid levels), pneumonia |
| CT abdomen/pelvis | Obstruction, appendicitis, pancreatitis, mass |
| Head CT / MRI | Suspected CNS etiology |
| Upper endoscopy | Chronic vomiting, hematemesis, suspected mucosal disease |
| Gastric emptying scan | Suspected gastroparesis |
Management
Immediate Priorities
- Assess and protect the airway (especially in altered consciousness)
- Assess hemodynamic status and volume depletion → IV crystalloid if severe
- Hold oral medications; find parenteral substitutes as needed
- Consider nasogastric tube if obstruction or high-output vomiting
Antiemetics
| Drug | Class | Mechanism | Dose | Notes |
|---|---|---|---|---|
| Ondansetron | 5-HT3 antagonist | CTZ + vagal GI terminals | 4–8 mg IV/PO | First-line; generally well-tolerated |
| Metoclopramide | D2/5-HT2 antagonist | CTZ + gastric motility | 10–20 mg IM/IV q6h | Risk of tardive dyskinesia (black box) |
| Prochlorperazine | D1/D2 antagonist | CTZ | 5–10 mg IM/PO; 25 mg PR | Extrapyramidal effects |
| Droperidol / Haloperidol | D2 antagonist | CTZ | 1.25 / 5 mg IV | QT prolongation monitoring |
| Promethazine | H1/muscarinic antagonist | Vestibular nucleus | 12.5–25 mg IM/IV | Sedating; IV route → tissue necrosis risk |
| Dimenhydrinate | H1 antagonist | Vestibular nucleus | 25–50 mg PO/IV | Motion sickness |
| Dexamethasone | Corticosteroid | CNS/undefined | 4–8 mg IV | PONV, chemotherapy-induced |
| Aprepitant | NK1 antagonist | Substance P/CTZ | 40–125 mg PO | PONV, chemotherapy |
| Scopolamine | Muscarinic antagonist | Vestibular nucleus | 1.5 mg patch | Motion sickness |
ED stepwise approach (Rosen's Emergency Medicine):
- Ondansetron 4 mg IV → repeat after 15–30 min if needed
- Add metoclopramide 10 mg IV if inadequate
- Consider droperidol 1.25 mg IV or haloperidol 5 mg IV (if mechanical obstruction excluded)
- Prochlorperazine 10 mg IV or promethazine 12.5 mg IM/IV if above fail
Special Situations
- Cannabinoid hyperemesis syndrome: cessation of cannabis (definitive); acute — capsaicin cream topically, haloperidol, or lorazepam; hot showers provide temporary relief
- Post-operative vomiting: aprepitant, ondansetron, dexamethasone, droperidol (combination additive); rule out anastomotic leak, ileus
- Pregnancy (hyperemesis gravidarum): pyridoxine (B6) ± doxylamine first-line; ondansetron second-line; IV fluids, thiamine supplementation
Sources: Tintinalli's Emergency Medicine; Rosen's Emergency Medicine; Guyton & Hall Textbook of Medical Physiology; Yamada's Textbook of Gastroenterology; S. Das Manual on Clinical Surgery; Goldman-Cecil Medicine
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