sigmoido-, sigmo- +

(Greek: sigmoeides, shaped like the letter sigma; pertaining to the sigmoid flexure, the S-shaped bend in the colon; a combining form that usually denotes the sigmoid colon)

sigmoidostomy (s) (noun), sigmoidostomies (pl)
A surgical operation creating an artificial anus in the sigmoid colon: A sigmoidostomy involves he formation of an artificial opening from the body surface into the sigmoid colon and the opening produced by this procedure.