Hollow Organ Perforation in Blunt Abdominal Trauma

Most Commonly Perforated Hollow Organ

• ROSEN's Emergency Medicine states: "Injury to any hollow viscus is uncommon by comparison [to solid organs], with the intestine the most likely hollow structure to be damaged."
• In seat belt injuries specifically: "The intestinal injury most commonly involves the jejunum" - ROSEN's Emergency Medicine, p. 487

Order of Hollow Organ Injury Frequency in Blunt Trauma

1. Small intestine (jejunum > ileum) - most common
2. Large intestine (colon)
3. Stomach
4. Urinary bladder (especially when full at time of impact)
5. Duodenum (retroperitoneal, less commonly)

Mechanisms of Hollow Organ Injury

1. Burst/crush injury - Sudden rise in intra-abdominal pressure compresses a hollow organ between the anterior abdominal wall and the vertebral column or posterior thoracic cage. A gas-filled or fluid-filled loop of bowel acts like a closed container and ruptures.
2. Shear injury - Rapid deceleration creates shear forces at fixed points of attachment (e.g., the duodenojejunal flexure, the ileocaecal junction), tearing the bowel at these transition zones.
3. Direct compression - As seen in seat belt injuries, the bowel is compressed between the lap belt and the vertebral column, producing contusion or perforation. The pathogenesis is: "compression of bowel between the belt and the vertebral column, resulting in a contusion or perforation of the intestines or a tear of the mesentery" - ROSEN's Emergency Medicine

Why the Jejunum Specifically?

• It is the most mobile segment of the small bowel
• It lies in the mid-abdomen, directly in the path of common blunt forces (steering wheel, lap belt)
• The duodenojejunal flexure (ligament of Treitz) is a fixed point that concentrates shear stress
• It has a relatively thin wall compared to the stomach

Important Clinical Points

• Hollow viscus injuries are notoriously difficult to detect on CT - CT is sensitive for solid organ injury but less so for bowel perforation. Subtle signs include bowel wall thickening, mesenteric fat stranding, free fluid without solid organ injury, and pneumoperitoneum.
• Presentation can be delayed by hours to days - initial signs may be absent or minimal, especially with small perforations.
• The "seatbelt sign" (abdominal abrasion/contusion from a lap belt) is highly correlated with intraperitoneal injury including bowel perforation and should prompt careful imaging and clinical observation.
• Free air on imaging = perforation until proven otherwise and mandates surgical exploration.

Summary Table