Rectal prolapse is a condition in which the rectum (the lower end of the colon, located just above the anus) becomes stretched out and protrudes out of the anus. The prolapse may comprise only of the inner lining of the rectum (rectal mucosa) and is called a ‘rectal mucosal prolapse’. This is similar to prolapsing hemorrhoids.

If the whole thickness of the rectal/bowel wall (both the inner mucosa and the outer muscle tube) has prolapsed, it is called a full thickness rectal prolapse or a complete rectal prolapse. On occasion, the prolapse may occur internally within the rectum (the rectum collapses inside itself).

In this situation, no obvious prolapse may be seen coming out through the anus. This condition called an internal intussusception. Because there may be no obvious external prolapse, it is more difficult to diagnose and may require specialist x-rays (proctogram) or scans.

Rectal prolapse is often associated with weakness of the anal sphincter muscle, resulting in leakage of stool or mucus. Although a prolapsed bowel may occur in both sexes, it is much more common in women. It is also more common in the elderly and but occasionally may occur in young children.

Why does rectal prolapse occur?

Several factors may contribute to the development of rectal prolapse. Risk factors include the following

• Chronic constipation: It may come from a lifelong habit of straining to have bowel movements
• Excessive straining: Conditions such as prostatic hypertrophy, pregnancy, a severe or a chronic cough may predispose to rectal prolapse
• The weak pelvic floor which may follow childbirth or previous surgery.
• Genetic predisposition: In children, rectal prolapse may occur in association with cystic fibrosis, Ehlers-Danlos syndrome and Hirschsprung’s disease
• Old age: It seems to be a part of the aging process in many patients who experience stretching of the ligaments that support the rectum inside the pelvis as well as the weakening of the anal sphincter muscle.
• Pelvic floor dysfunction, in association with urinary incontinence and pelvic organ prolapse as well.
• Neurological problems, such as spinal cord transection, spinal cord disease or multiple sclerosis may predispose to a prolapsed bowel.

In most cases, however, no single cause is identified.

What are the symptoms of rectal prolapse?

The most obvious symptom of rectal prolapse is a lump or swelling coming out of the anus. Initially, this may only occur after a bowel movement. However, as the condition develops it may also happen when coughing or even when standing up.

With internal intussusception rectal prolapse, no lump or swelling comes through your anus. However, patients complain of a feeling of not having completely emptied their bowels, and many patients correctly describe actually feeling something sitting inside the rectum/anus.

With an external prolapse, it may be possible to push the prolapsed bowel back in. However, it may become difficult and as soon as it is pushed back in, it may protrude out again. Occasionally, it may not be possible to push it back in at all (termed ‘reduce the prolapse’).

Many patients with a rectal prolapse also notice that they have less than perfect control of their bowel movements. They may soil their underwear or have a slimy discharge from the rectum. These symptoms can make it difficult to maintain good hygiene. Occasional, bleeding may occur from the rectum and discomfort in the area.

How is rectal prolapse diagnosed?

A doctor can often diagnose this condition with a careful history and a complete anorectal examination. To demonstrate the prolapse, patients may be asked to sit on a commode and “strain” as if having a bowel movement.

Occasionally, a rectal prolapse may be "hidden" or internal, making the diagnosis more difficult. In this situation, an x-ray examination called a defecating proctogram may be helpful. This examination, which takes x-ray pictures while the patient is having a bowel movement, can also assist the colorectal specialist in determining whether surgery may be beneficial and which operation may be appropriate.

Anorectal manometry and an endoanal ultrasound may also be used to evaluate the function of the muscles around the rectum as they relate to having a bowel movement. These tests are especially relevant if the rectal prolapse is associated with poor control (fecal incontinence).

If rectal bleeding or a change in bowel function occurs in association with the rectal prolapse, a telescope assessment of the colon may be necessary. This is called a flexible sigmoidoscopy (examination of the lower 1/3 of the rectum and colon) or a colonoscopy.

How is rectal prolapse treated?

In the early stages, a minor rectal mucosal may respond to the relief of constipation and strain by taking plenty of fruit and vegetables and other foods that contain fiber. Bulking laxatives, such as Fybogel may also help with bowel function.

In children, rectal prolapse usually gets better without any specific treatment. However, as with adults, it is important to avoid straining and parents or a child with rectal prolapse will be advised to ensure their child has plenty of fruit, vegetables and water in their diet, as well as foods that contain fiber.

Although constipation and straining may contribute to the development of a rectal prolapse, simply correcting these problems are unlikely to fix a full thickness rectal prolapse once it has developed. There are many different ways to surgically correct rectal prolapse.

Ultimately, an operation may be required.  This may be performed via the abdomen or directly on the prolapse at the anus. The decision to recommend either abdominal or rectal surgery is based on a number of factors including age, physical condition, the extent of prolapse, and the results of various tests.

An abdominal repair (rectopexy) aims to lift the rectum up and fix it so that it cannot prolapse out through the anus again. For many patients, this can be performed laparoscopically (keyhole repair of the prolapsed bowel). The repair is often reinforced with mesh to get the best long-term results. The most modern version of these operations is called a Laparoscopic Ventral Mesh Rectopexy (LVMR).

Rectal surgery may need to be performed in frail patients who are not suitable or not fit enough for an abdominal rectopexy. The most commonly performed rectal operation in this situation is called a DeLorme’s procedure. This is performed at the anus and may even be performed under spinal anesthetic rather than a general anesthetic.