Bilious Vomiting and Ileus
Bilious vomiting is indeed a symptom of ileus, but more critically, it indicates that any obstruction—whether functional (ileus) or mechanical—is located distal to the ampulla of Vater, and this finding demands urgent evaluation to exclude life-threatening surgical emergencies.
Understanding the Clinical Significance
The presence of bile in vomitus is a red flag that transcends the simple diagnosis of ileus 1. While ileus (functional bowel obstruction) can certainly present with bilious vomiting, this symptom indicates the obstruction point is beyond where bile enters the gastrointestinal tract 2, 1. The critical distinction is that bilious vomiting represents intestinal obstruction until proven otherwise—whether from functional ileus or mechanical causes—and requires immediate attention 3, 4.
Pathophysiology in Ileus
In the context of ileus specifically:
- Functional or paralytic ileus causes diffuse gastrointestinal dysmotility affecting both small and large intestine 5
- This leads to intestinal dilatation and increased luminal pressure 5
- When the obstruction involves the small bowel distal to the ampulla of Vater, bilious material accumulates and is eventually vomited 1
- The blockage prevents normal antegrade flow of intestinal contents, including bile 5
Critical Differential Considerations
The presence of bilious vomiting should never be assumed to be "just ileus" without excluding mechanical obstruction, particularly:
In Neonates and Infants:
- Malrotation with midgut volvulus (20% of bilious vomiting cases in first 72 hours of life) 1
- Intestinal atresia (duodenal, jejunal, ileal) 1
- Hirschsprung disease 1
- Intussusception in older infants 1, 6
In Post-Surgical Patients:
- After gastric bypass surgery, bilious vomiting specifically indicates obstruction at the jejuno-jejunostomy level 2
- Internal hernia (53.9% of late small bowel obstruction after RYGB) 2
- Adhesive disease 2
Diagnostic Approach
Do not delay imaging based on clinical suspicion of "simple ileus":
- Obtain immediate abdominal radiograph to assess for dilated bowel loops, air-fluid levels, and gas patterns 1, 6
- Normal radiographs do NOT exclude mechanical obstruction—if bilious vomiting persists, proceed to upper GI contrast series (96% sensitivity for malrotation) 1
- In post-bariatric surgery patients with bilious vomiting, early exploratory laparoscopy is mandatory to avoid intestinal vascular compromise 2
Common Pitfall to Avoid
The most dangerous error is attributing bilious vomiting to benign postoperative ileus or functional causes without excluding mechanical obstruction, particularly malrotation with volvulus, which can cause intestinal necrosis within hours 1. The American College of Radiology explicitly states that clinical suspicion based on bilious vomiting alone mandates proceeding to definitive imaging regardless of initial radiograph findings 1.
Systemic Consequences
When ileus does cause bilious vomiting, recognize the potential for: