Estimation of the stent placement above the intact sphincter of Oddi against malignant bile duct obstruction

Background. In endoscopic biliary stenting against malignant biliary obstruction, stent blockage remains as an important problem. Stent blockage occurs as a result of bacterial adherence to the inner wall of the stent. We evaluated the stent placement above the intact sphincter of Oddi to retain the function of the sphincter of Oddi as a bacteriological barrier. Methods. Sixteen patients with malignant biliary obstruction were assessed as the patients with the stent above the intact sphincter of Oddi. Sixteen patients with malignant biliary obstruction were assessed as the patients with the conventional stent placement across the sphincter of Oddi. Tannenbaum 10-Fr. stents were used in both the groups. Results. The median patency periods of the stent were 255 days (25th to 75th percentiles, 212-454 days; range, 39-454 days) for the group of the stents placed above the sphincter of Oddi and 82 days (25th to 75th percentiles, 48-131 days; range, 22-196 days) for the group of the stents placed across the sphincter of Oddi, respectively, with significant difference (P = 0.0001). The occlusion rates of stents placed above and across the sphincter of Oddi were 37.5% and 93.8%, respectively, with significant difference (P = 0.0008). The dislocation rates of the stent were 0% and 6.3%, respectively (not significant). Conclusions. Placement of the stent above the intact sphincter of Oddi was associated with longer stent patency and lower occlusion rate.