A restrained front-seat passenger survives a head-on collision. He has a linear bruise across the lower abdomen from the lap belt. CT shows rupture of the jejunum with a tear of its mesentery. The mechanism of this hollow viscus injury is:

• A Shearing of the bowel at fixed retroperitoneal attachments during deceleration alone
• B Crushing of bowel between the belt and the vertebral column with sudden rise in intraluminal pressure ✓
• C Direct penetration by a fractured pelvic bone
• D Ischaemic necrosis from prolonged belt compression over hours

Explanation

B lap belt compresses the mobile small bowel against the lumbar spine, and the sudden compression spikes intraluminal pressure, causing blow-out rupture typically of the proximal jejunum, often with mesenteric tearing. Deceleration shearing explains duodenal and renal avulsion at fixed points, but jejunal rupture under a seat belt sign is chiefly a crush and pressure phenomenon. There is no penetrating element and the injury is immediate, not ischaemic.

Reference: Bailey and Love's Short Practice of Surgery, 28th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.