Rectal Prolapse

Prolapse of tissue from the anus implies that the mass whatever it is due to can be replaced into the bowel. This can only be done if the mass is based inside the anus.

A mass based outside cannot prolapse. Internal haemorrhoids can prolapse. External haemorrhoids with few exceptions cannot do so.
The pictures below show some of the conditions that can prolapse.

Figure 1. Prolapsed Fibroepithelial polyp. Usually called Anal polyp

Figure 2. Prolapsed internal haemorrhoids

Figure 3. Prolapsed anal mucosa

This article deals with Rectal Prolapse, a specific type where the rectum turns itself inside out . The complete wall of the bowel is involved in this. It can be known as full thickness prolapse or procidentia of the rectum. The process begins above the sphincter muscles which normally hold in the poo. As it passes downwards it stretches these muscles until the inside of the bowel appears outside. See Figure 4. If it is prevented by the sphincters from reaching the outside, it is known as an internal prolapse or intusussception.

On occasion only part of the circumference appears outside the anus. It is then known as partial prolapse. See Figure 5.

Quite commonly only the inner lining of the bowel is involved. This is known as mucosal prolapse, a condition akin to prolapsing internal haemorrhoids. See Figures 2. and 3.

Aetiology

The cause of rectal prolapse is not fully understood. The following are thought to be involved.

1. Chronic constipation and straining.
2. Weak sphincter muscles.
3. A previous hysterectomy.
4. Diseases of the spinal cord.
5. Reduced fixity of the rectum to the wall of the pelvis.

Incidence

The problem is relatively rare. It can affect children under the age of 4, but all ages can be involved. The elderly are more prone to the problem. 80% of patients are women.

Clinical features

1. A lump appears at the anus during a bowel action. At first this lump returns inside spontaneously. Later it has to be pushed back manually. The mass can be quite small but it can become several centimetres in length.
2. In time the prolapse occurs without a bowel movement and if replaced recurs immediately.
3. Pain is not necessarily a feature but can be quite severe.
4. Bleeding results from the prolapse which chafes against the underclothes.
5. Mucus is secreted from the prolapse making it appear that the patient is incontinent of faeces. Eventually real incontinence ensues.

Diagnosis

This is usually self evident. It may be embarrassing for the patient to demonstrate the prolapse to the doctor. A colonoscopy is necessary to ensure that no other conditions such as colonic polyps or cancers are present. Other tests are also performed in order to assess the patients fitness for any proposed procedure.

Treatment

Children can be treated expectantly. Consult with your doctor before adopting this strategy. The prolapse is replaced with each nappy change as necessary. Most children improve spontaneously.

Adults probably require an operation. The type of operation should be discussed with your doctor and surgeon.

Some operations obtain the best results by fixing the rectum to the wall of the pelvis. Other possibilities include the removal of excess bowel and joining the open ends of the remaining bowel by anastomosis. Very infirm patients do better if the bulk of the rectum is increased by multiple pleating of the redundant rectum and replacing it above the sphincters so it cannot prolapse.

Figure 4. Full thickness prolapse of rectum

Figure 5. Partial Prolapse of rectum.

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