In small bowel obstruction, which of the following is the most common cause in the developed world?

Explanation

## Epidemiology of Small Bowel Obstruction Causes **Key Point:** Adhesions account for 60–75% of all small bowel obstructions in the developed world, primarily from prior abdominal or pelvic surgery. ### Cause-Specific Breakdown | Cause | Frequency (%) | Common Scenario | |-------|---------------|------------------| | Adhesions | 60–75 | Post-surgical (most common) | | Hernias | 10–15 | Inguinal, femoral, incisional | | Malignancy | 10–15 | Extrinsic compression or intraluminal | | Volvulus | 5–10 | Sigmoid > small bowel | | Crohn's disease | 5–10 | Strictures in terminal ileum | | Other (intussusception, foreign body) | <5 | Rare in adults | **High-Yield:** Adhesions are the leading cause in post-operative patients; hernias are the leading cause in patients with no prior surgery. ### Why Adhesions Dominate 1. **Mechanism:** Peritoneal trauma during surgery triggers fibrin deposition and collagen remodeling, creating fibrous bands. 2. **Timeline:** Can form weeks to years after surgery; risk increases with number of prior procedures. 3. **Prevention:** Minimal-access surgery (laparoscopy) reduces adhesion formation compared to open surgery. **Clinical Pearl:** A patient presenting with small bowel obstruction and a history of abdominal surgery has adhesions until proven otherwise — this guides imaging and management strategy. **Tip:** In exam questions, if the patient has prior surgery, always think adhesions first; if no prior surgery, think hernias or malignancy.