Rethinking Right Upper Quadrant (RUQ) Pain: The Role of Lemmel Syndrome in Biliary Obstruction.

Lemmel syndrome involves a periampullary duodenal diverticulum (PAD), a pouch-like outpouching near the ampulla of Vater, compressing the common bile duct. We describe a case of severe abdominal pain in a patient who had a large periampullary diverticulum, managed with surgical intervention after an initial failed endoscopic retrograde cholangiopancreatography (ERCP). An elderly female patient in her early 90s arrived at the emergency department with severe cramping pain localized to the right upper quadrant of her abdomen, progressively intensifying over several weeks. Her blood pressure measured 161/68 mmHg, while other vital signs and the physical exam showed no abnormalities. A CT scan of the chest, abdomen, and pelvis with IV contrast revealed both biliary and pancreatic duct dilation, along with choledocholithiasis and a possible obstructing lesion at the pancreatic head. Further imaging with MRI and MRCP confirmed choledocholithiasis, dilation of the common bile duct (CBD), and the presence of a duodenal diverticulum. The initial attempt at endoscopic retrograde cholangiopancreatography (ERCP) was unsuccessful due to a large periampullary diverticulum, leading to the placement of a temporary percutaneous cholecystostomy tube. In a subsequent ERCP, the stones were successfully removed. During the same hospital stay, she underwent cholecystectomy and was later discharged. Patients experiencing right upper quadrant (RUQ) pain should consider Lemmel syndrome as one of the differential diagnoses. Although rare, it is a treatable condition that, if overlooked, can result in repeated hospitalizations and ongoing investigations. The altered anatomy associated with this syndrome can complicate standard medical procedures, requiring physicians to adapt their approach and utilize alternative methods.