Obstructed Defaecation Syndrome (ODS)

What is ODS?
Obstructed defaecation syndrome is a common condition in which a person is unable to evacuate their bowels properly.

What causes ODS?
Generally ODS is caused by the structural abnormalities associated with a weak pelvic floor or prolapse disease (intussusception or internal rectal prolapse, rectocoele). Less commonly (about 5-10%), a tight pelvic floor is the cause.

What symptoms do patients get?
This syndrome is characterised by difficulty passing motions, multiple (often unsuccessful) visits to the toilet, a sensation of a blockage and incomplete emptying. Patients with ODS often use their finger to help them to empty, pushing on the perineum (the skin in front of the anal canal), on the back wall of the vagina or in the anal canal itself. Patients often have some symptoms of faecal incontinence.

Which test will I need?
After an examination in clinic, we may recommend a flexible sigmoidoscopy or colonoscopy to rule out rare causes for ODS. Anorectal physiology and endoanal ultrasound will help distinguish a weak from a tight pelvic floor. A proctogram looks at the co-ordination of the pelvic structures during defaecation. A transit study will check to see if the colon is sluggish and failing to propel its contents to the rectum for defaecation.

Which treatments might be offered?
Often patients can be helped with changes in diet or stool softeners. Pelvic floor retraining retrains the muscle of the pelvic floor and co-ordinates the muscles better. For those failing to improve with these measures and evidence of a structural cause for ODS such as an intussusception or rectocoele, surgery such as laparoscopic ventral rectopexy, STARR or rectocoele repair may be indicated.