The high rate of spontaneous migration of small size common bile duct stones may allow a significant reduction in unnecessary ERCP and related complications: results of a retrospective, multicenter study

Introduction Common bile duct stones (CBDS) can spontaneously migrate through the duodenal papilla. In this case, ERCP could be unnecessary and a significant rate of complications could be avoided. In this study, we aim at retrospectively evaluating the rate of spontaneous stone passage in patients with an imaging diagnosis of CBDS and at analysing the factors associated to spontaneous stone migration. Methods We conducted a retrospective multi-centre analysis of patients undergoing ERCP for CBDS in a 12-month period. 1016 patients with CBDS were analysed. In all patients CBDS was diagnosed with adequate imaging methods performed prior to ERCP. ERCPs with failed biliary cannulation were excluded. Data regarding patients’ characteristics, imaging findings and ERCP procedure were analysed. Results 1016 patients with CBDS undergoing ERCP were analysed (male sex 43.3%; mean age 69.9 ± 16.5 years). Diagnosis of CBDS was obtained by EUS in 415 patients (40.8%), MR in 343 (33.8%), CT in 220 (21.7%), and US in 38 (3.7%). No stones were found at ERCP in 179 patients (17.6%), in 14 (6.2%) when ERCP was performed within 6 h from imaging study, in 114 (18.5%) between 7 h and 7 days, in 32 (24.6%) between 8 and 29 days, and in 19 (43.2%) after 30 days. The rate of unnecessary ERCP occurred significantly more frequently in patients in whom imaging methods demonstrated either sludge or ≤ 5 mm CBDS (29.9 vs. 8.3%; p < 0.001). Discussion Spontaneous migration of small CBDS is a frequent event, and ≤ 5 mm size and a delay in ERCP > 7 days represent predictive factors for it. We suggest that CBDS ≤ 5 mm should not undergo immediate removal and this fact would allow reducing the rate of unnecessary ERCP with their related complications. Prospective studies are needed to confirm these results and demonstrate the safety of a conservative management in this setting.