DEFINITION & PATHOPHYSIOLOGY

Vomiting: Forceful oral expulsion of gastric contents associated with contraction of abdominal and chest wall musculature.
Regurgitation: Involuntary, effortless expulsion of small amounts of gastric contents unaccompanied by nausea or abdominal muscular contraction,.
Pathophysiology: Mediated by intestinal visceral afferent nerves stimulating the vomiting center in the central nervous system (CNS).
Complications: Dehydration, hypokalemic hypochloremic metabolic alkalosis, malnutrition,. Vigorous vomiting risks mucosal tear (Mallory-Weiss syndrome), esophageal rupture (Boerhaave syndrome). Severe vomiting causes aspiration pneumonia, shock, pneumomediastinum, and petechiae.

ETIOLOGY BY AGE

Age Group	Acute/Common Causes	Chronic/Persistent Causes
Infant (1–12 mo)	Gastroenteritis, systemic infection, overfeeding, anatomic obstruction, pertussis,.	Gastroesophageal Reflux Disease (GERD), eosinophilic esophagitis, celiac disease, adrenal insufficiency, Hirschsprung disease.
Child (1–11 y)	Gastroenteritis, systemic infection, toxic ingestion, medications, sinusitis, otitis media,.	Peptic ulcer disease (PUD), gastroparesis, celiac disease, eosinophilic esophagitis, cyclic vomiting syndrome.
Adolescent (12–18 y)	Gastroenteritis, appendicitis, toxic ingestion, drug overdose, diabetic ketoacidosis,.	Pregnancy, eating disorders (bulimia), cannabinoid hyperemesis syndrome, superior mesenteric artery syndrome,.

System	Conditions
Gastrointestinal	Pyloric stenosis, malrotation, intussusception, appendicitis, pancreatitis, cholecystitis, hepatitis, foreign body impaction.
Neurologic	Brain tumor, hydrocephalus, pseudotumor cerebri, migraine, seizure, meningitis, Chiari malformation.
Metabolic/Endocrine	Urea cycle defect, organic acidopathy, galactosemia, diabetic ketoacidosis, adrenal insufficiency.
Respiratory/Misc.	Pneumonia, sinusitis, sepsis, pregnancy, Munchausen by proxy, psychogenic vomiting.

Presentation: Non-bilious, projectile vomiting immediately after feeding,. Onset typically between 3 and 6 weeks of age,.
Pathophysiology: Thickened, elongated pylorus causing gastric outlet obstruction.
Examination: Firm, olive-shaped mass palpable in mid-epigastrium; visible left-to-right peristaltic wave,.
Complications: Hypochloremic, hypokalemic metabolic alkalosis,.
Diagnosis: Ultrasound demonstrates thickened muscle (>4 mm) and elongated pyloric channel (>16 mm),.

Criteria: Stereotypic episodes of intense nausea and vomiting; return to baseline health between episodes; not attributed to other disorders,,.
Presentation: Early morning onset,. Autonomic surge symptoms: lethargy, pallor, tachycardia, abdominal pain,. Vomiting peaks at 6 times per hour.
Associations: Family history of migraines; motion sickness. Triggered by fasting, lack of sleep, stress, infection,.

Definition: Delayed gastric emptying without mechanical outlet obstruction.
Etiology: Often post-viral; secondary causes include diabetes mellitus, hypothyroidism, muscular dystrophy, opioid use.
Presentation: Nausea, postprandial vomiting containing undigested food, early satiety, bloating,. Liquids tolerated better than solids.
Diagnosis: Gastric emptying nuclide scintigraphy or antroduodenal manometry.

Presence mandates immediate admission and urgent evaluation,.

Bilious emesis (green vomit suggests malrotation/volvulus until proven otherwise),.
Hematemesis or gastrointestinal bleeding,.
Severe abdominal pain with distension or tenderness,.
Persistent tachycardia or hypotension.
Neck stiffness, photophobia, altered mentation, bulging fontanelle, seizures,,.
Onset of persistent vomiting >6 months of age.

Differentiate bilious vs. non-bilious emesis. Lesions distal to ampulla of Vater cause bilious vomiting; proximal lesions cause non-bilious vomiting,.
Assess hemodynamic status and hydration degree (capillary refill, fontanelle, tachycardia).
Neurologic exam for increased intracranial pressure.

Metabolic/Electrolytes: Basic metabolic panel (sodium, potassium, chloride, CO2) to assess alkalosis/acidosis; Blood urea nitrogen (BUN) and creatinine,.
Organ Function: Amylase, lipase, liver transaminases,.
Specialized: Venous pH, blood glucose, ketones, serum ammonia, lactate, pyruvate (if metabolic disorder suspected),. Urinalysis and urine culture. Urine pregnancy test in adolescents.

Plain Radiographs (KUB): Identifies foreign bodies, obstruction, or perforation,.
Ultrasonography: Test of choice for pyloric stenosis, intussusception, cholelithiasis, or hydronephrosis,,,.
Upper GI Barium Series: Mandatory for bilious emesis to rule out malrotation and midgut volvulus,,.
CT/MRI Brain: Indicated for suspected subtentorial masses, Chiari malformations, or unremitting early morning emesis with neurologic signs,.
Esophagogastroduodenoscopy (EGD): Evaluates peptic ulcer disease, eosinophilic esophagitis, or mucosal lesions,.

Ensure airway protection and hemodynamic stability.
Intravenous (IV) isotonic crystalloid fluids indicated for severe dehydration, failed oral rehydration, or hemodynamic compromise,.
Nasogastric (NG) decompression for suspected obstruction or severe distension.

Ondansetron: Serotonin 5-HT3 antagonist. Reduces vomiting related to acute gastroenteritis, chemotherapy, and cyclic vomiting syndrome,,. Decreases need for IV hydration and hospital admission. Dose: 0.15-0.3 mg/kg/dose IV/PO,.
Contraindications: Routine use of antiemetics (phenothiazines, metoclopramide) avoided in undiagnosed children due to severe extrapyramidal and neurologic side effects,.

Cyclic Vomiting Syndrome: Dark, quiet environment. Abortive therapy with sumatriptan; prophylactic therapy with amitriptyline, cyproheptadine, or propranolol,,.
Pyloric Stenosis: Correction of fluid and electrolyte derangements (hypochloremic alkalosis) strictly precedes surgical Ramstedt pyloromyotomy,.
Malrotation with Volvulus: Emergent laparotomy and Ladd's procedure,.