Radiology insights into Petersen's hernia complication of post Roux-en-Y gastric bypass

Following gastrojejunostomy in Roux-en-Y gastric bypass (RYGB), the mesentery is susceptible to Petersen's hernia due to a mesenteric gap created between the alimentary limb, transverse mesocolon, and retroperitoneum. Although the Petersen's hernia is a rare complication, it has increased due to the widespread adoption of gastric bypass surgeries for weight management and gastric cancer resections. Computed tomography (CT) is commonly used to evaluate suspected cases. We present a case of a 36-year-old female who developed Petersen's hernia 3 weeks post RYGB. This report highlights key radiologic features, such as the whirl sign and mushroom-shaped mesentery in recognizing Petersen's hernia. Given the small sample sizes in current literature, this case contributes valuable evidence to aid clinicians in radiologically detecting Petersen's hernia.