The role of common bile duct (CBD) stenting in the establishment of bile stream in the elderly patients and the ones who are not good candidates for surgery due to not responding to treatments was well documented in previous studies. The current study aimed at investigating the effect of adding Ursodeoxycholic acid (UDCA) to CBD stenting alone in order to reduce the size of large and multiple CBD stones.

Clinical outcomes including success rates in CBD stones clearance, incidence of pancreatitis, perforation, bleeding, as well as, decrease in size of stones and liver enzymes after a two-month period were assessed in the UDCA + CBD stenting group.

A total of 64 patients referring to Shahid Beheshti Hospital in Qom, Iran with multiple or large CBD stones (above three or larger than 15 mm) received standard endoscopic therapies and UDCA + CBD stenting (group B) and controls only received standard endoscopic therapies with only CBD stenting (group A). The mean reduction in the size of stones in group B was significantly higher than that of group A (3.22 ± 1.31 vs 4.09 ± 1.87 mm) (p = 0.034). There was no difference in the incidence rate of complications including pancreatitis, cholangitis, bleeding, and perforation between the two groups (P > 0.05).

Adding UDCA to CBD stenting, due to decrease in the stone size and subsequently facilitation of the stones outlet, can be considered as the first-line treatment for patients with large and multiple CBD stones. Also, in the cases with large or multi stones may be effective in reducing size and subsequently stone retrieval. Trial registry The study protocol was approved by the Ethics Committee of Qom University of Medical Sciences (ethical code: IR.MUQ.REC.1397.075); the study was also registered in the Iranian Registry of Clinical Trials (No. IRCT20161205031252N8). This study adheres to CONSORT guidelines.