Protrusion of rectal mucous membrane (incomplete prolapse) or mucous membrane and rectal wall (complete prolapse) through the anus. Incomplete prolapse occurs quite often in children, in whom it can be caused by problems in defecation. In adults with complete prolapse, weakening of the pelvic muscles and loose ‘suspension’ of the rectum can be factors. Symptoms consist of difficulties with defecation, including an increase of the prolapse during defecation, and possibly swelling, haemorrhage and irritation of the mucous membrane and even tissue death. With complete prolapse diagnosis can easily be made by inspection. Treatment is by surgery to suspend the rectum more securely. In mild cases the diet should be adjusted so that less pressure is needed for defecation.