Computed Tomography Patterns in Small Bowel Obstruction after Open Distal Gastric Bypass

Background: Life-threatening small bowel obstruction (SBO) after Roux-en-Y gastric bypass can present with surprisingly minimal laboratory and plain x-ray findings. Based on a 10-year (1994-2003) experience of 1,409 open distal gastric bypasses, we present clinical and radiological findings in 29 patients with unusual forms of bowel obstruction. Methods: A retrospective chart review was conducted. A radiologist experienced in reviewing these in gastric bypass patients reviewed all computed tomography (CT) scans. Results: CT findings: The normal appearance and 7 recurring patterns of small bowel obstruction were identified. These include: 1) intussusception, 2) internal hernia through Petersen's space, 3) through Petersen's space and the mesenteric defect at enteroenterostomy, 4) through the mesenteric defect from the entero-enterostomy, 5) isolated biliary limb obstruction, 6) segmental non-anastomotic ischemia, and 7) internal hernia through bands. Clinical findings: 1 had peritonitis, and 1 had free air on plain film. WBC count was normal in 20/27 patients (74%) including 5/6 (83%) with dead bowel. 9/14 patients (62%) had "non-specific" findings on x-rays. 7 of these had an internal hernia (2 with volvulus and 2 with dead bowel), 1 had biliopancreatic limb obstruction, and 1 had peritonitis. Conclusion: Patients with SBO after distal gastric bypass may present with vague complaints and confusing laboratory and non-specific findings on x-rays. Delayed diagnosis can have catastrophic consequences. CT imaging with oral and intravenous contrast can be life-saving, and should be obtained in all gastric bypass patients with abdominal pain, particularly when all other parameters seem "normal". Unexplained abdominal pain should prompt exploration.