To evaluate the efficacy and safety of ultrathin choledochoscopy for patients with gallbladder stones complicated by non-dilated extrahepatic bile duct stones. MethodsThis retrospective study included patients with gallbladder stones complicated by non-dilated extrahepatic bile duct stones who were treated at the Department of Hepatobiliary and Pancreatic Surgery, Huai’an Clinical College of Xuzhou Medical University, from January 2024 to December 2025. Patients were divided into two groups based on different treatment strategies: the ultrathin choledochoscopy group (n=66) underwent laparoscopic cholecystectomy (LC) combined with transcystic ultrathin choledochoscopy for common bile duct stone extraction; the endoscopic group (n=61) received LC combined with intraoperative endoscopic retrograde cholangiopancreatography. Clinical outcomes were compared between the two groups. ResultsA total of 127 patients were enrolled, including 66 in the ultrathin choledochoscopy group and 61 in the endoscopic group. Compare with endoscopic group, the ultrathin choledochoscopy group exhibited significantly shorter operation time [(82.15±17.87) min vs. (104.26±23.99) min, P＜0.001], shorter time to first postoperative flatus [(1.77±0.78) d vs. (2.19±0.79) d, P=0.004], and shorter length of hospital stay [(4.98±1.99) d vs. (5.89±2.65) d, P=0.032]; lower white blood cell count [(9.95±2.57)×10?/L vs. (11.09±3.28)×10?/L, P=0.033], neutrophil count [(7.20±2.26)×10?/L vs. (8.22±2.58)×10?/L, P=0.021], hypersensitive C-reactive protein [(39.79±17.58) mg/L vs. (48.43±20.04) mg/L, P=0.012] on postoperative day 1; lower total hospital costs [(2.00±0.26)×104 yuan vs. (2.64±0.32)×104 yuan, P＜0.001], as well as a lower total complication rate [1.52% (1/66) vs. 10.53% (6/57), P=0.048]. The ultrathin choledochoscopy group achieved a higher surgical success rate than the endoscopic group [100% (66/66) vs. 93.44% (57/61), P=0.049]. During the follow-up, no patients in either group presented with bile duct stricture, reflux cholangitis, or stone recurrence. ConclusionThe ultrathin choledochoscopy approach via the cystic duct has advantages in operative duration, early postoperative recovery, and total hospital costs, and provides a novel treatment option for patients with gallbladder stones complicated by non-dilated extrahepatic bile duct stones.