Internal herniation through Petersen's defect following Roux-en-Y gastric bypass presenting as subacute bilateral lower extremity edema due to IVC compression - a case report.

A 38-year-old woman with a history of Roux-en-Y gastric bypass (RYGB) 2 years prior presented to the bariatric clinic on multiple occasions with postprandial abdominal pain and bloating and bilateral lower extremity edema. Abdominal pain did not improve despite antiacid medication and dietary recommendations. Computed tomography scan of the abdomen revealed an internal hernia (IH) through Petersen's defect (a potential space between the Roux limb and transverse colon), with a mass effect on the inferior vena cava by herniated bowel. Diagnostic laparoscopy confirmed the diagnosis. Reduction of the hernia and defect closure resulted in full symptom resolution. This case highlights the importance of high clinical suspicion for IH in any patient with a history of RYGB and abdominal pain, even when symptoms are chronic and/or atypical. Early recognition is important for prompt treatment and prevention of bowel ischemia and necrosis.