Internal hernia: an increasingly common cause of small bowel obstruction.

Internal hernia is an uncommon cause of small bowel obstruction that may be increasing in frequency. Because the clinical diagnosis of internal hernia is difficult, imaging studies such as computed tomography (CT) and small bowel follow through play an important role. Transmesenteric hernia is the most common type and is usually related to prior abdominal surgery, especially with creation of a Roux-en-Y anastomosis (eg, liver transplantation, gastric bypass). CT may allow confident diagnosis in most cases. In this article, we review the clinical and imaging findings of internal hernia based on our experience with 54 cases of surgically proven internal hernias including 45 transmesenteric, 6 paraduodenal, and 3 omental hernias, 39 of which had imaging studies available for review.