Vomiting: Comprehensive Etiology, Red Flags, and Management Approach

Vomiting (emesis) is a coordinated reflex: nausea → retching → expulsion. It protects against toxins but signals diverse pathology.

Etiologic Categories

Category	Examples	Key Clues
GI obstruction	SBO, pyloric stenosis, intussusception, malignancy	Distension, absolute constipation, high-pitched bowel sounds
GI inflammation/infection	Gastroenteritis, appendicitis, cholecystitis, pancreatitis, hepatitis	Fever, diarrhea, localized pain, jaundice
Metabolic/endocrine	DKA, adrenal crisis, uremia, hypercalcemia, thyrotoxicosis	Polyuria, dehydration, electrolyte abnormalities
Neurologic	Increased ICP (tumor, hemorrhage, IIH), migraine, vestibular, concussion	Headache, papilledema, focal deficits, nystagmus
Toxic/iatrogenic	Chemo, opioids, antibiotics, alcohol, cannabis hyperemesis	Temporal relation to exposure, dose-dependent
Psychogenic	Bulimia, conversion, anxiety, factitious	No weight loss (bulimia), stress trigger, normal workup
Pregnancy	NVP, hyperemesis gravidarum	Gestational age, ketonuria, Wt loss >5%

Red Flags for Urgent Evaluation

• Hematemesis / coffee-ground emesis.
• Bilious (green) vomiting in infant — surgical emergency (malrotation).
• Projectile vomiting in infant 3–6 wks — pyloric stenosis.
• Signs of dehydration (orthostasis, oliguria, poor skin turgor).
• Neurologic signs (lethargy, focal deficit, papilledema).
• Duration >24–48 hrs (adults) / >12 hrs (children).

Initial Management

1. IV fluids (NS/RL) + electrolyte repletion (K⁺, Mg²⁺).
2. Antiemetics: ondansetron 4–8 mg IV/PO, metoclopramide, prochlorperazine — choose by etiology.
3. NPO → advance to clear liquids → BRAT as tolerated.
4. Targeted workup (CBC, BMP, LFTs, lipase, β-hCG, imaging per suspicion).