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

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.