Common bile duct size in malignant distal obstruction and lumen-apposing metal stents: a multicenter prospective study.

Feasibility of EUS-guided choledochoduodenostomy (EUS-CDS) using available lumen-apposing stents (LAMS) is limited by the size of the common bile duct (CBD) (≤ 12 mm, cut-off for experts; 15 mm, cut-off for non-experts). We aimed to assess the prevalence and predictive factors associated with CBD size ≥ 12 and 15 mm in naïve patients with malignant distal biliary obstruction (MDBO). This was a prospective cohort study involving 22 centers with assessment of CBD diameter and subjective feasibility of the EUS-CDS performance in naïve jaundiced patients undergoing EUS evaluation for MDBO. A total of 491 patients (mean age 69 ± 12 years) with mean serum bilirubin of 12.7 ± 6.6 mg/dL entered the final analysis. Dilation of the CBD ≥ 12 and 15 mm was detected in 78.8 % and 51.9 % of cases, respectively. Subjective feasibility of EUS-CDS was expressed by endosonographers in 91.2 % for a CBD ≥ 12 mm and in 96.5 % for a CBD ≥ 15 mm. On multivariate analysis, age (  < 0.01) and bilirubin level (  ≤ 0.001) were the only factors associated with both CBD dilation ≥ 12 and ≥ 15 mm. These variables were poorly associated with the extent of duct dilation; however, based on them a prediction model could be constructed that satisfactorily predicted CBD size ≥ 12 mm in patients at least 70 years and a bilirubin level ≥ 7 mg/dL. Our study showed that at presentation in a large cohort of patients with MDBO, EUS-CDS can be potentially performed in three quarters to half of cases by expert and less experienced endosonographers, respectively. Dedicated stents or devices with different designs able to overcome the limitations of existing electrocautery-enhanced LAMS for EUS-CDS are needed.