Introduction: Petersen's space hernia is an internal hernia that can occur after Roux-en-Y gastrojejunostomy. The intestinal loops herniate through a defect between the retroperitoneum, the transverse mesocolon and the small bowel limbs. We present a case of recurrent pancreatitis in a patient with Roux-En-Y bypass found to have common channel hernia through a Petersen's space defect. Case Description/Methods: We present the case of a 34-year-old female with a history of Roux-en-Y surgery in 2018 and subsequent recurrent pancreatitis who presented to the emergency department with a chief complaint of severe epigastric and left lower quadrant abdominal pain associated with hematemesis. Patient reported 3 episodes of pancreatitis within 1 year previously. CT abdomen and pelvis showed mildly dilated common bile duct and intrahepatic biliary dilatation with no evidence of pancreatitis. Significant lab work included elevated lipase at 184 U/L. Patient was admitted to the medical service. Gallbladder ultrasound revealed no evidence of cholelithiasis, a prominent CBD of 9 mm and redemonstrated mild intrahepatic biliary dilatation. MRCP revealed a mesenteric swirl in the mid abdomen which was suspicious for an internal hernia in the setting of antecolic Roux-en-Y gastric bypass. It also showed focally dilated intrahepatic with underlying segmental atrophy. General surgery consultation was sought, with eventual plans for diagnostic laparoscopy after ruling out marginal ulcer via EGD. An EGD was performed which did not show evidence of marginal ulcer. Patient then underwent diagnostic laparoscopy which revealed a 360-degree volvulus of the common channel through a Petersen's space defect; this was carefully reduced, and the Petersen's space defect was closed. Patient also underwent laparoscopic cholecystectomy. Patient did not have any further episodes of pancreatitis after surgery. Discussion: This case demonstrates recurrent pancreatitis in a patient with a history of Roux-En-Y bypass found to have a common channel volvulus through a Petersen's space defect. It is our understanding that the volvulus likely caused compression of the pancreaticobiliary system, thus causing recurrent pancreatitis. Reduction of the volvulus and closing of the Petersen's defect resulted in complete resolution of recurrent pancreatitis in the patient.

Gallbladder agenesis is a rare congenital anomaly of the biliary tract, due to failure of the gallbladder and cystic duct budding off of the common bile duct during fetal development. Cholangiocarcinoma (CCA) is a malignant tumor arising from the biliary ducts in patients with underlying chronic biliary tract inflammation, primary sclerosing cholangitis, or other diseases. Although few studies have reported cases of cholelithiasis in patients with congenital gallbladder agenesis, there is only one other known case of concomitant cholangiocarcinoma and congenital gallbladder agenesis. Herein we present a case of recurrent gallstones in a male, diagnosed with gallbladder agenesis intraoperatively and with pathology consistent with cholangiocarcinoma.