Large Bowel Obstruction
Kathryn Welp
Background
- Mostly occurs distal to the transverse colon due to decreased colonic lumen diameter.
- 60% due to colon cancer, often the initial presenting symptom..
- Ddx: SBO, toxic megacolon, Ogilvie’s syndrome, paralytic ileus, ischemic colitis
Etiology
- Malignancy
- Benign
- Volvulus (cecal, sigmoid)
- Strictures (associated with diverticular disease, IBD, prior colorectal resection)
- Fecal impaction
- Less common: adhesions, hernia
Presentation
- Bloating, infraumbilical crampy abdominal pain, and obstipation
- Focal tenderness or peritoneal signs is concerning for ischemia
- N/V can occur with proximal obstructions or in incompetent ileocecal valve
- In subacute cases: change in bowel patterns over time
Evaluation
- CBC w/ diff, BMP, CEA (if imaging concerning for malignancy)
- Abdominal CT: >90% sensitivity and specificity for detecting LBO. Demonstrates dilated colon proximal to a transition point with collapsed distal colon.
- 3-6-9 rule (describes normal bowel diameter): small bowel <3 cm, large bowel <6 cm, cecum <9 cm
- Abdominal XR: nonspecific with poor sensitivity.
Management
- Oral bowel prep contraindicated.
- Initial supportive care: bowel rest, electrolyte correction, IVF, and gastric decompression.
- Unstable: peritoneal signs, closed-loop obstructions → emergency surgery
- Stable:
- Endoscopic stenting (more commonly for L-sided obstructions)
- Malignant obstructions require surgery for definitive management
- Volvulus:
- Cecal → surgery
- Sigmoid → endoscopic detorsion before semi-elective surgery (unless unstable)
