What is the approach to managing vomiting and determining its underlying cause?

Approach to Vomiting and Determining its Underlying Cause

The approach to vomiting should begin with categorizing the type of vomiting (bilious vs. non-bilious), assessing for red flag signs, and systematically evaluating potential causes based on patient age and clinical presentation. 1

Initial Assessment

• Assess airway, breathing, and circulation to ensure patient stability 2
• Evaluate hydration status - critical for determining immediate management needs 2, 3
• Look for red flag signs that indicate serious conditions requiring urgent intervention:
  • Bilious or bloody vomiting (suggests obstruction distal to ampulla of Vater) 1
  • Altered mental status 2
  • Toxic/septic appearance 2
  • Severe dehydration 2, 4
  • Bent-over posture (suggests peritoneal irritation) 2

Categorization of Vomiting

Based on Duration

• Acute vomiting (less than 1 month): Usually self-limited infections, medication effects, or acute obstruction 5
• Chronic vomiting (1 month or longer): May indicate functional disorders, gastroparesis, psychiatric causes, or malignancy 5

Based on Content

• Non-bilious vomiting: Often gastroesophageal reflux, gastroparesis, or proximal obstruction 1
• Bilious vomiting: Suggests obstruction distal to ampulla of Vater - surgical emergency until proven otherwise 1

Age-Specific Differential Diagnosis

Infants

• Gastroesophageal reflux (common, usually benign) 1
• Pyloric stenosis (non-bilious projectile vomiting, usually at 2-8 weeks) 1
• Malrotation with volvulus (bilious vomiting, surgical emergency) 1
• Intestinal atresia or stenosis 1
• Hirschsprung disease 1
• Metabolic disorders (presenting with lethargy, acidosis) 1
• Increased intracranial pressure (bulging fontanelle) 1

Children

• Gastroenteritis (most common cause of acute vomiting) 2, 3
• Appendicitis (associated with migration of pain to right lower quadrant) 2
• Intussusception (intermittent colicky pain, bloody stools) 1
• Diabetic ketoacidosis 2
• Toxic ingestions 2
• Infections outside GI tract (otitis media, UTI, pneumonia, meningitis) 2, 5

Adults

• Gastroenteritis 5
• Medication effects 5
• Pregnancy 5
• Bowel obstruction 5
• Gastroparesis 1
• Cyclic vomiting syndrome 1
• Malignancy 5
• Psychiatric causes 5

Diagnostic Approach

History Elements to Focus On

• Timing and onset of vomiting 5
• Character of vomitus (bilious, bloody, feculent) 1
• Associated symptoms (pain, diarrhea, fever, headache) 5
• Medication use and recent changes 5
• Recent travel or food exposure 3
• Surgical history (risk for adhesive obstruction) 5

Physical Examination

• Vital signs with focus on signs of dehydration 2, 4
• Abdominal examination (distension, tenderness, masses) 5
• Neurological examination (focal deficits, papilledema) 2
• Specific findings to look for:
  • Palpable "olive" in right upper quadrant (pyloric stenosis) 1
  • Visible peristalsis (obstruction) 5
  • Surgical scars (adhesive obstruction risk) 5

Laboratory Studies

• Based on clinical suspicion, consider:
  • Electrolytes and renal function (assess dehydration and metabolic status) 2, 3
  • Complete blood count (infection, inflammation) 5
  • Liver function tests and lipase (hepatobiliary or pancreatic disease) 5
  • Urinalysis (UTI, ketones in DKA) 5
  • Pregnancy test in females of childbearing age 5
  • Stool studies if infectious etiology suspected 3, 5

Imaging Studies

• Abdominal radiography: Initial study for suspected obstruction 5
• Ultrasound: First-line for suspected pyloric stenosis, appendicitis, intussusception 1
• CT scan: For suspected appendicitis, obstruction, or when diagnosis remains unclear 5
• Head CT: When increased intracranial pressure is suspected 2, 5
• Upper GI series: For suspected malrotation 1
• Gastric emptying study: When gastroparesis is suspected 1

Management Approach

Immediate Management

• Fluid resuscitation for dehydration:
  • Oral rehydration therapy for mild-moderate dehydration without persistent vomiting 3
  • IV fluids (20-30 mL/kg isotonic crystalloid) for severe dehydration or persistent vomiting 4
• NPO status and nasogastric tube for suspected bowel obstruction 5
• Correction of electrolyte abnormalities 1

Pharmacologic Management

• Antiemetics (based on suspected cause):
  • Ondansetron: 0.15 mg/kg IV or 0.2 mg/kg oral (max 4 mg) for persistent vomiting 6, 2
  • Prochlorperazine: 5-10 mg PO every 6-8 hours for adults 1, 7
  • Metoclopramide: For gastroparesis-related vomiting 1
• Acid suppression for suspected gastritis or GERD:
  • Proton pump inhibitors or H2 blockers 1

Cause-Specific Management

• Surgical consultation for suspected obstruction, appendicitis, intussusception 1
• Antibiotics for bacterial infections 3
• Specific therapy for underlying metabolic or endocrine disorders 2
• Prophylactic antiemetics for radiation or chemotherapy-induced vomiting 1

Special Considerations

Cyclic Vomiting Syndrome

• Consider in patients with recurrent episodes of intense vomiting between symptom-free periods 1
• First-line prophylaxis: Tricyclic antidepressants 1
• Abortive therapy: Sumatriptan plus antiemetics during prodromal phase 1

Cannabis Hyperemesis Syndrome

• Consider in patients with chronic cannabis use and cyclic vomiting 1
• Diagnosis requires cessation of cannabis for at least 3-6 months with resolution of symptoms 1

Breakthrough Vomiting

• Use antiemetics from different drug classes 1
• Consider alternative routes (IV, rectal, sublingual) when oral route not feasible 1
• Ensure adequate hydration and correct electrolyte abnormalities 1

Common Pitfalls to Avoid

• Attributing all vomiting to gastroenteritis without considering other causes 2, 5
• Failing to recognize bilious vomiting as a potential surgical emergency 1
• Missing metabolic causes of vomiting, particularly in infants 1
• Inadequate fluid resuscitation leading to worsening dehydration 4, 3
• Overlooking medication side effects as a cause of vomiting 5