Saline irrigation for reducing the recurrence of common bile duct stones after lithotripsy: a randomized controlled trial

BACKGROUND: Mechanical lithotripsy produces stone fragments that are not easily detected by cholangiography and is a potential cause of recurrence of common bile duct stones (CBDS). This study aims to clarify whether 100 ml saline irrigation after mechanical lithotripsy reduces the recurrent rate of CBDS. METHODS: In this randomized controlled trial performed at the Surgical Endoscopy Center, the First Hospital of Lanzhou University between May 10, 2019, and Dec 31, 2020, patients undergoing endoscopic mechanical lithotripsy were randomly assigned to receive saline irrigation (study group) or no irrigation (control group). The saline irrigation was given 100 ml saline pulse irrigation after cholangiography showed no residual stones. Patients were followed up for at least 24 months after endoscopic stone removal to assess the recurrence of CBDS. This study was registered with ClinicalTrials.gov (NCT03937037). FINDINGS: During the median follow-up period of 35.6 months (interquartile range, 26.0–40.7), 43 of the 180 patients had stone recurrence (24%). The frequency of recurrence of CBD stones was 12.22% in the saline irrigation group and 35.56% in the control group, with a difference of 23.33% between the two groups (95% confidence interval [CI], 11.35%–35.32%, p < 0.001). Multivariable Cox proportional hazards analyses showed that constipation (hazard risk [HR] 2.42; 95% CI, 1.22–4.80, p = 0.012), periampullary diverticulum (PAD) (HR 3.06; 95% CI, 1.62–5.79, p < 0.001), and total to direct bilirubin ratio (HR 1.48; 95% CI, 1.21–1.81, p < 0.001) were independent risk factors for the recurrence of CBDS. Saline irrigation was the only preventive factor for the recurrence of CBDS (HR 0.22; 95% CI, 0.11–0.44, p < 0.001). INTERPRETATION: For patients with CBDS requiring mechanical lithotripsy, 100 ml saline irrigation effectively reduces the recurrent rate of CBDS after endoscopic stone removal. FUNDING: This work was supported by 10.13039/501100001809National Natural Science Foundation of China (32160255); 10.13039/501100004775Natural Science Foundation of Gansu Province (22JR5RA898, 20JR10RA676); Science and Technology Planning Project of Chengguan District in Lanzhou (2020JSCX0043).