Introduction: Hemorrhage is a known potential complication of endoscopic retrograde cholangiopancreatography (ERCP), often occurring at the site of sphincterotomy. Less commonly, intra- and retroperitoneal hemorrhage can occur secondary to splenic, hepatic, or vascular injury. Here we present a rare case of inferior pancreaticoduodenal artery (IPDA) pseudoaneurysm (PSA) rupture following ERCP in a patient with a large diaphragmatic hernia. Case Description/Methods: The patient is a 68 year old man with a history of hypertension, chronic kidney disease, and splenectomy. He presented with jaundice, fatigue, and labs notable for hypoglycemia, acidemia, acute kidney injury, normal transaminase levels, alkaline phosphatase (129 IU/L), total bilirubin (4.2 mg/dL), direct bilirubin (2.5 mg/dL), and lipase (157 IU/L). Computed tomography (CT) with contrast revealed choledocholithiasis with a 1.2 cm stone in the head of the pancreas associated with pneumobilia, intra- and extrahepatic ductal dilation, and pancreatic ductal dilation. A large left diaphragmatic hernia with protrusion of nonobstructed loops of large and small bowel into the left hemithorax was also noted. He underwent ERCP with biliary sphincterotomy and removal of one stone. One large stone remained. A plastic stent was placed in the common bile duct with plans to repeat ERCP in 4-6 weeks with cholangioscopy and electrohydrolic lithotripsy. Following ERCP, the patient developed acutely worsening anemia without overt evidence of lumenal gastrointestinal bleeding. CT angiography revealed active extravasation and a PSA within an intra-abdominal hematoma (18.4 x 8.5 cm). The patient then underwent mesenteric angiography which showed one multilobulated (2 x 1.8 cm) and one smaller PSA arising from an IPDA branch. Coil embolization of the dominant PSA was performed, achieving hemostasis. (Figure, Table) Discussion: Visceral artery aneurysm (VAA) rupture is an exceedingly rare complication of ERCP with IPDA pseudoaneurysms accounting for just 2% of VAA. Although there is a known association of VAA with pancreatitis, the mechanism for PSA formation following ERCP is unclear. It is thought to be associated with sphincterotomy with rupture caused by direct mechanical injury related to pancreaticobiliary manipulation. Mortality related to VAA rupture and hemorrhage can be as high as 19%. A high index of suspicion and early detection followed by angioembolization are critical for reducing mortality.Figure 1.: (A) CT with contrast showing choledocholithiasis with a 1.2 cm stone in the head of the pancreas. (B) CT angiography showing active extravasation and a pseudoaneurysm (PSA) within an intra-abdominal hematoma (18.4 x 8.5 cm). (C) Mesenteric angiography which showed one multilobulated (2 x 1.8 cm) and one smaller PSA arising from an inferior pancreaticoduodenal artery branch. Table 1 - Summary of currently available case reports of inferior pancreaticoduodenal artery (IPDA) pseudoaneurysm (PSA) development following endoscopic retrograde cholangiopancreatography (ERCP) Age/Sex Comorbidities ERCP Indication Interventions Symptom Diagnosis Treatment Al-Jeroudi et al 2001 76 F None Palliation of pancreatic carcinoma Precut sphincterotomy, biliary stent Abdominal pain IPDA PSA Embolization Rim et al 2021 27 M Sickle cell disease Choledocholithiasis Sphincterotomy, stone extraction, biliary stent, pancreatic duct stent Abdominal pain, acute anemia IPDA PSA rupture Embolization Current Case 68 M Hypertension, chronic kidney disease, diaphragmatic hernia Choledocholithiasis Sphincterotomy, stone extraction, biliary stent Abdominal pain, acute anemia IPDA PSA rupture Embolization