Balloon Enteroscopy‐assisted Endoscopic Retrograde Cholangiopancreatography for Choledocholithiasis in Situs Inversus Totalis With Billroth II Reconstruction: A Case Report and Literature Review

ABSTRACT Endoscopic retrograde cholangiopancreatography (ERCP) in patients with situs inversus totalis (SIT) and Billroth II reconstruction is technically challenging because of mirror‐image anatomy, altered access to the papilla, and inverted papillary orientation. A 56‐year‐old man with a history of distal gastrectomy with Billroth II reconstruction for a gastric ulcer 20 years earlier was found to have common bile duct stones on pre‐ERCP imaging. ERCP was performed in the prone position, as in conventional ERCP, with the endoscopist standing on the patient's right side. A short‐type single‐balloon enteroscope was advanced through the afferent limb to the major papilla. Biliary cannulation was achieved using a standard ERCP catheter without positional modification or sphincterotome. Cholangiography confirmed small common bile duct stones. Endoscopic papillary balloon dilation with an 8‐mm balloon was performed, followed by stone extraction using a basket catheter. Final cholangiography confirmed complete stone clearance, and no adverse events, including post‐ERCP pancreatitis, occurred. This case suggests that favorable alignment between the 7 o'clock working‐channel direction and the bile duct axis may allow conventional‐position ERCP in selected patients with SIT and Billroth II reconstruction.