For some membranes, mucus also acts as a lubricant that prevents friction and tearing of the mucous membrane tissue when objects pass through them. For example, mucus in the vagina reduces friction during sexual intercourse and mucus in the gastrointestinal tract (including the rectum) facilitates the passage of food and feces. Mucus in the . Anal Mucus Discharge (Overview) Anal mucous discharge is a symptom in which a person has mucous coming out of his anus (either mucous by itself, or mucous mixed with stool/poop). Infection and autoimmune disease (when a person's own immune system is over-active against himself) can cause anal mucous discharge. In IV degree prolapse, the dentate line is positioned almost outside the anal canal, and the rectal mucous membrane permanently occupies the muscular anal canal. top Procedure for Prolapse and Hemorrhoids (PPH).