J Korean Surg Soc 2013;84:225-230

There were term errors at the end portion of third paragraph in METHODS section of main text. The previous 'rectal tenesmus' should be replaced by bold 'push action' as follow.

PA was defined when posterior wall of the rectum was not or poorly straightened with push action. PE was defined when zone of evacuation (a portion of the rectum below distal transverse fold) was not or poorly emptied until 40 seconds after the anal canal opened. Push action was defined effective when perineal descent and concave change of upper border of the rectum were noted. Anatomical changes were defined when there was obvious anterior bulging (RE), or funnel-shaped deformity (IN) of the rectum with push action.