The difficulties rose from: (1) benign stenosis of ampulla Vater, incarcerated stones or anatomical deformities (n=187) resulting in insufficient insertion of sphincterotome;

• 困难的原因187例为乳头良性狭窄，壶腹部结石嵌顿或解剖异常，致切开刀未能插入足够的深度；