What is bilious vomiting?

Bilious Vomiting: Definition and Clinical Significance

Bilious vomiting refers to the forceful expulsion of bile-containing gastric contents, which appears green or yellow-green in color, and is a concerning clinical sign that suggests intestinal obstruction requiring urgent evaluation, especially in neonates and infants.

Definition and Characteristics

Bilious vomiting is characterized by:

• Green or yellow-green colored vomitus due to presence of bile
• Indicates reflux of intestinal contents proximal to the ampulla of Vater
• Distinguished from non-bilious vomiting by its color and clinical implications

Clinical Significance

In Neonates (0-28 days)

Bilious vomiting in neonates is an ominous sign that requires immediate attention:

• Surgical emergency until proven otherwise 1
• In neonates within the first 72 hours of life, 20% had midgut volvulus and 11% had lower GI causes 1
• 46% of term neonates with bilious vomiting have a surgical diagnosis 2
• 14.1% have time-critical surgical conditions where delay may compromise gut viability 2

Common Causes in Neonates

1. Intestinal obstruction:

   • Duodenal atresia (classic "double bubble" sign on imaging)
   • Jejunal atresia ("triple bubble" sign)
   • Malrotation with midgut volvulus (requires urgent surgery)
   • Ileal atresia
   • Hirschsprung disease

2. Other causes:

   • Meconium ileus
   • Meconium plug syndrome
   • Internal hernia
   • Duodenal web
   • Obstructing duplication cyst

In Older Children and Adults

• Jejunal stricture due to non-specific jejunoileitis 3
• Bile reflux gastritis (post-gastrectomy condition) 4
• Chronic partial bowel obstruction
• Adhesions from previous surgery

Diagnostic Approach

Initial Evaluation

• Abdominal radiographs are the first-line imaging study 1
• Look for patterns suggesting:
  • Proximal obstruction: double or triple bubble sign
  • Distal obstruction: multiple dilated loops with absent or minimal distal gas

Secondary Imaging

Based on initial radiographic findings:

1. For suspected proximal obstruction (double/triple bubble):

   • Usually no additional imaging needed before surgery 1
   • In some cases, air can be injected through feeding tube to better delineate gas pattern

2. For suspected distal obstruction:

   • Contrast enema is the diagnostic procedure of choice 1

3. For non-classic findings or normal gas pattern:

   • Upper GI series to evaluate for malrotation or midgut volvulus 1
   • Ultrasound may be used to evaluate superior mesenteric vein/artery relationship

Clinical Pearls and Pitfalls

Important Clinical Findings

• Abdominal distension (74% sensitivity for surgical diagnosis) 2
• Abdominal tenderness (62% sensitivity) 2
• Abnormal abdominal X-ray (97% sensitivity) 2

Pitfalls to Avoid

• Delaying surgical consultation when bilious vomiting is present in a neonate
• Failing to recognize bilious vomiting as potentially indicating a time-critical surgical condition
• Misinterpreting normal abdominal X-ray (reduces probability of surgical diagnosis from 50% to 16%, but does not exclude it) 2

Key Point

All term neonates with bilious vomiting should be prioritized as time-critical cases requiring prompt evaluation and management 2.