Inferior pancreaticoduodenal artery aneurysm presenting as a highly vascularized lesion by the papilla Vateri: presentation of a case and review of the literature.

We report a case of a 60-year-old male who developed a large retroperitoneal haematoma following endoscopic retrograde cholangiopancreatography (ERCP). Initial imaging suggested a distal common bile duct calculus and a small highly vascularized lesion in the periampullary region, but ERCP revealed no stones, and no sphincterotomy or balloon dilation was performed. Post-procedure, the patient developed severe abdominal pain with subsequent haemodynamic instability. Computed tomography angiography demonstrated active bleeding from aneurysm of the inferior pancreaticoduodenal artery, successfully embolized via the superior mesenteric artery. The patient recovered with supportive care and percutaneous drainage of residual haematomas. This case highlights the rare but serious complication of vascular injury following ERCP, even without invasive biliary interventions.