Common bile duct stone removal with overtube-assisted direct peroral cholangioscopy, without balloon inflation, using an ultra-slim gastroscope following electrohydraulic lithotripsy.

who presented with obstructive jaundice due to a large (2.5 cm) stone in the common bile duct (CBD). We attempted mechanical lithotripsy but the stone was too big for the basket (●" Fig. 1). We decided to break the stone with electrohydraulic lithotripsy (EHL) and carry out direct peroral cholangioscopy instead of motherbaby endoscopy. In our experience, the mother-baby endoscopic system has several disadvantages. The caliber of the working channel is too narrow and it requires two experienced endoscopists for carrying out the procedure. In addition, the baby endoscope is rather fragile and we have had to very often send it back to the company for repair. Therefore, overtube-assisted direct peroral cholangioscopy using an ultra-slim gastroscope was the preferred intervention in this patient. Before the procedure, we made a hole at 70 cm from the distal end of the overtube of a single-balloon enteroscope (ST-SB1, Olympus, Tokyo, Japan) [1,2] (●" Fig. 2). Then, an ultra-slim gastroscope (GIF-N260; Olympus, Tokyo, Japan) with a 2-mmworking channel and 5.9-mm outer diameter was inserted through the hole. In the next step, first the CBD was cannulatedwith a duodenoscope using a sphincterotome and 0.035-inch jag wire, and then the duodenoscope was replaced with the ultra-slim gastroscope with the overtube over the wire. The overtube was advanced over the scope into the antrum. The overtube was useful for keeping the endoscope straight when inserted in the stomach as it prevented loop formation during advancement of the scope at a more accessible angle to the papilla. Then, without balloon inflation, the gastroscope was supported by the overtube and advanced over the wire into the bile duct (●" Fig. 3). The CBD stone was visualized (●" Fig. 4) and EHL was carried out to break the stone into several pieces. The stone fragments were removed using a Common bile duct stone removal with overtubeassisted direct peroral cholangioscopy, without balloon inflation, using an ultra-slim gastroscope following electrohydraulic lithotripsy