Rectal prolapse

Rectal prolapse is the protrusion of part of the rectum through the anus. This may occur in childhood but is usually more common in the elderly. This condition occurs mainly in women but may also occur in men. The exact cause is unknown, and is more common in people who excessively strain and in women who have had multiple vaginal or assisted deliveries. As a result, it is believed to be due to a weakness in the pelvic floor and sphincter muscles of the anus. When it occurs in childhood the treatment is usually conservative as it usually resolves overtime without surgery.

Patients usually experience prolapse during defecation that normally spontaneously reduces "back up" without any manipulation. Overtime it is necessary to manually push the prolapsing bowel back. Pain is not usually a feature of rectal prolapse but patients may experience some discomfort. More common symptoms include episodes of incontinence to flatus and faeces, bleeding and the passage of mucus, and the sensation of incomplete evacuation or constipation.

There are three main types of rectal prolapse:

• Internal prolapse: the bowel telescopes on the inside and does not prolapse through the anus
  
  
• Partial prolapse: the inner mucosal lining of the rectum protrudes out of the anus
  
  
• Full thickness prolapse: complete protrusion of the bowel through the anus.

Inspecting the anus and asking the patient to "bare down", which usually demonstrates protrusion of the bowel except in patients with an internal prolapse, usually makes the diagnosis. On occasion, examination under anaesthetic is necessary or a special X-ray called a defecating proctogram is required. All patients should undergo a colonoscopy as part of  their investigations to exclude any other sinister pathology. Patients with incontinence should have anorectal physiology (manometry, pudendal nerve conduction studies, transrectal ultrasound) to assess sphincter and nerve function.

Treatment is aimed at prevention of straining and constipation to reduce episodes. These measures include stool bulking agents (e.g. Normafibre) and biofeedback. Biofeedback retrains patient's toileting habits. It educates patients regarding the correct sitting position on the toilet and benefits of fitness and adequate fluid intake. Surgical treatment is either performed through the anus (locally) aimed at resecting the redundant mucosa or bowel or through the abdomen aimed at suspending and fixing the rectum to the sacrum. Local procedures involve banding of mucosa and stapling excision (STARR) of redundant mucosa. Abdominal procedures are typically performed by "keyhole surgery" (laparoscopic) and involves fixation of the rectum to the sacrum. In elderly high risk patients fixing the prolapse through the anus is the preferred approach. These procedures involve removing the inner lining of the prolapsing bowel (Delorme's procedure) or resecting the prolapsing bowel (Altemeier's procedure).

The success rates vary amongst the procedures and the choice of procedure depends on age, health and type of prolapse. Success rates for abdominal procedures are best however many patients experience an element of constipation post-operatively which improves with time.

Reviewed 2017