“…There are 2 possible explanations for the lack of protective effect: the expansive force of the SEMS may be so strong that ES cannot protect the pancreatic orifice, and/ or the axial (straightening) force of the SEMS may directly affect the pancreatic orifice rather than being limited to the incised duodenal mucosa as previously reported. 19,20 The rates of perforation and bleeding in the ES group were only 0% and 1%, respectively, and were comparable with previously reported rates for covered SEMS (0%-0.7% and 0%-2%, respectively). 4,5,[7][8][9][11][12][13][14][15] These rates are relatively low compared with those for ES for extraction of bile duct stones, and this may be attributable to the wrapping and tamponade effect of covered SEMS because the covering membrane may seal tiny perforations and other minor vessel injuries that occur during ES.…”