What causes yellow vomiting?

Yellow Vomiting: Causes and Clinical Significance

Yellow vomiting is most commonly caused by the presence of bile in the vomitus, which indicates that the vomiting originates from below the pylorus of the stomach, potentially signaling intestinal obstruction or other serious gastrointestinal conditions.

Pathophysiology of Yellow Vomiting

Yellow vomiting occurs when bile, produced by the liver and stored in the gallbladder, is present in the vomitus. This happens through several mechanisms:

1. Bilious vomiting: When bile from the duodenum refluxes back into the stomach and is then expelled
2. Intestinal obstruction: Blockage below the entry point of bile into the small intestine
3. Prolonged vomiting: After stomach contents are emptied, bile-containing intestinal contents appear

Common Causes of Yellow Vomiting

Serious/Urgent Causes

• Intestinal obstruction or malrotation: Bilious vomiting is the most concerning symptom in neonates and infants with intestinal malrotation 1
• Gastric outlet obstruction: May benefit from treatment with corticosteroids, endoscopic stenting, or insertion of a decompressing G-tube 2
• Small bowel obstruction: Requires prompt surgical evaluation
• Pyloric stenosis: Common in infants, presents with projectile vomiting that becomes bilious

Non-Urgent Causes

• Gastroenteritis: Leading cause of acute vomiting in children 3
• Prolonged/severe vomiting episodes: After stomach contents are emptied, bile appears
• Medication side effects: Many medications can cause nausea and vomiting 2
• Cyclic vomiting syndrome: Characterized by recurrent episodes of nausea, vomiting, and abdominal pain 4

Evaluation of Yellow Vomiting

Red Flag Signs Requiring Immediate Attention

• Bilious (yellow/green) vomiting: May indicate intestinal obstruction
• Bloody vomiting: Suggests mucosal damage or bleeding
• Altered mental status: May indicate central nervous system involvement
• Severe dehydration: Requires immediate fluid resuscitation
• Abdominal distension or tenderness: Suggests possible obstruction or peritonitis
• Bent-over posture: May indicate peritoneal irritation 3

Diagnostic Approach

1. Assessment of hydration status: Check for signs of dehydration

2. Laboratory tests:

   • Serum electrolytes (look for metabolic alkalosis in prolonged vomiting)
   • Renal and liver function tests
   • Blood gases if severe dehydration is present 3

3. Imaging studies:

   • For suspected obstruction: Upper GI series (96% sensitivity for malrotation) 1
   • Ultrasonography: Can evaluate anatomical landmarks and detect "whirlpool sign" specific for volvulus 1

Management of Yellow Vomiting

Immediate Management

1. Assess airway, breathing, and circulation
2. Treat dehydration: Fluid and electrolyte replacement
3. For bilious vomiting: Stop oral fluids/feeds and decompress the stomach with nasogastric tube 3

Pharmacological Management

For symptomatic relief when appropriate:

1. Serotonin (5-HT3) antagonists:

   • Ondansetron: 0.15 mg/kg IV or 0.2 mg/kg oral (maximum 4 mg) 3
   • Granisetron: 2 mg PO or 1 mg PO BID or 0.01 mg/kg IV 2
   • Palonosetron: 0.25 mg IV (preferred for chemotherapy-induced nausea/vomiting) 2

2. Dopamine receptor antagonists:

   • Prochlorperazine, haloperidol, metoclopramide, olanzapine 2

3. Other options for persistent nausea:

   • Corticosteroids (dexamethasone)
   • Benzodiazepines (for anxiety-related nausea)
   • Anticholinergic agents and/or antihistamines 2

Non-Pharmacological Management

• Small, frequent meals
• Avoidance of trigger foods
• Adequate hydration
• Consider proton pump inhibitors or H2 receptor antagonists if gastritis or gastroesophageal reflux is suspected 2

Special Considerations

Chemotherapy-Induced Yellow Vomiting

• Follow antiemetic protocols based on the emetogenic potential of the chemotherapy regimen
• Combination therapy with 5-HT3 antagonists, NK1 antagonists, and dexamethasone is recommended for highly emetogenic chemotherapy 2

Radiation-Induced Yellow Vomiting

• Prophylaxis based on the site of radiation and whether combined with chemotherapy
• For upper abdominal radiation: ondansetron (8 mg, 2-3 times daily) with or without dexamethasone 2

Pitfalls and Caveats

1. Never ignore bilious vomiting, especially in infants and children, as it may indicate life-threatening intestinal obstruction requiring surgical intervention

2. Consider non-gastrointestinal causes of vomiting, including:

   • Brain metastases or increased intracranial pressure
   • Metabolic disorders (hypercalcemia, uremia)
   • Medication side effects
   • Vestibular disorders 2

3. Distinguish between acute and chronic vomiting:

   • Acute (≤7 days): Typically treated symptomatically
   • Chronic (≥4 weeks): Requires more extensive evaluation 5

4. Consider dyspepsia as a mimic: Patients sometimes have difficulty discriminating heartburn from nausea 2

Yellow vomiting should never be dismissed as insignificant, particularly in infants and children where it may represent a surgical emergency requiring prompt intervention.