The Usefulness of Short-Type Single Balloon Enteroscope for Successful Pancreato-Biliary Cannulation During Endoscopic Retrograde Cholangiopancreatography in Patients With Roux-en-Y Gastrectomy: A Comparative Study With Short-Type Double-balloon Enteroscope.

Objectives: The retroflex position is crucial for the success of pancreato-biliary cannulation in patients with Roux-en-Y gastrectomy (RYG). We aimed to investigate the factors associated with forming the retroflex position in patients with RYG, including short-type single-balloon enteroscope (sSBE) and short-type double-balloon enteroscope (sDBE). Methods: 119 consecutive patients who underwent endoscopic retrograde cholangiopancreatography (ERCP) after RYG were enrolled. All the procedures were performed using sSBE (SIF-H290S; Olympus Medical Systems, Tokyo, Japan) or sDBE (EI-580BT; Fujifilm, Tokyo, Japan). The clinical outcomes of ERCP were compared between patients undergoing ERCP with sSBE (n = 65) and sDBE (n = 54). A logistic regression model was used to identify the independent factors associated with retroflex position. Results: The overall cannulation success rate was 76.7% in patients with RYG. Multivariate analysis revealed that retroflex position was the only independent factor associated with successful cannulation (Odds Ratio [OR] 6.996​, 95% Confidence Interval [95%CI] 2.604-20.703, p = 0.0001). In the sub-analysis using two types of scopes, sSBE, but not sDBE, was identified as an independent factor associated with the retroflex position (OR 7.025​, 95%CI 2.750-20.001, p = 0.0001). Decision tree analysis also revealed that the scope was the first splitting variable for the retroflex position. The retroflex position rate was 42.9% and 81.5% in patients with sDBE and sSBE, respectively. Conclusions: The retroflex position was the most useful factor for the cannulation success rate in patients with RYG. Moreover, we first demonstrated that sSBE was more useful than sDBE for forming the retroflex position. Thus, sSBE may be better for patients with RYG through easier formation of the retroflex position than sDBE.