Rectal Prolapse

Prolapse, in medical terminology, refers to the weakening of attachments and subsequent protrusion and displacement of an organ, or part of it, from its normal site and position. Commonly, prolapses of the uterus, vagina, rectum and heart valves can occur. The rectum is the final segment of the large intestine that ends at the anus, which is the terminal portion of the digestive tract, through the opening of which feces are expelled. Rectal prolapse refers to the undue and abnormal descent of the rectum, due to various factors, which causes it to telescope into the anus, fall outward and get turned inside out. A lump thus appears at the opening of the anal canal. While initially, it appears only when straining over the toilet or during a bowel movement (retracting spontaneously after the passage of stool), later the rectum can even descend, and remain out, under the influence of gravity while standing or walking. Eventually, it may remain outside at all times.

Three types of rectal prolapse are defined on the basis of the degree of the prolapse – internal, partial or complete rectal prolapse.

• Internal rectal prolapse is said to occur when the rectum begins to drop but no part of it has emerged foutside from the anal opening yet.
• Depending on the layers of the rectal wall extruded, there are two other types of rectal prolapse.
  • Partial, when only the rectal mucosa hangs outside by a few centimetres.
  • Complete, when all layers of the rectal wall, and the rectum in its entirety, are out. Although not a medical emergency, more severe degrees of rectal prolapse can adversely affect the patient’s quality of life. 

Prolapse of the rectum commonly afflicts the elderly, with older females at the highest risk. However, rectal prolapse can also occur in children, especially in the paediatric age group of 1 to 3 years.

(Read more: Rectopexy)

The final segment of the large intestine, the rectum, descends abnormally downward (or prolapses) due to various factors impairing the support required by it. Essentially, the following key principles are involved in rectal prolapse:

• Dysfunction of adjacent supports: Such as lax pelvic floor muscles or anal sphincter
• Abnormal motility of the intestines: As with constipation, which causes one segment of the intestine to telescope into the next one, producing the phenomenon of intussusception or internal prolapse (does not hang outside the anal sphincter), which progresses to total rectal prolapse
• Anatomical defects or variations: Like rectal polyps 
• Increased intraabdominal pressure: Like chronic constipation or chronic obstructive pulmonary disease (COPD), which cause the disease to progress 

(Read more: Kegel exercises)

Due to these factors, the rectum passes through the funnel formed in the muscular pelvic floor, and upon passing bowel movements it telescopes (intussusception) into the anus producing an internal prolapse. The attachments of the rectum begin to relax causing the middle portion to lengthen and the anal sphincter to stretch out over time. The rectum then descends through this lax opening outside and a rectal prolapse occurs.

Additionally, due to several anatomical differences involving the rectum and the adjoining structures in early childhood, younger children are naturally more prone to developing rectal prolapse. In childhood, the rectum is at a relatively lower position compared to the other pelvic organs and it also follows a vertical course along the sacrum and coccyx bones of the pelvis. The mucosa of the rectum is redundant and attaches to the underlying muscularis only very loosely. As compared to in adults, the sigmoid colon in children is more mobile and the levator ani muscles of the pelvic floor and underdeveloped Houston valves provide lesser support and structural integrity in infants under 1 year of age (3). Lastly, some congenital disorders like cystic fibrosis, myelomeningocele, Hirschsprung disease, spina bifida and congenital hypothyroidism predispose children to the possibility of rectal prolapse.

Usually the first sign of a rectal prolapse is the sensation of a bulge or lump at the anal opening. At first, the lump protrudes only during a bowel movement, receding back to normal after passage of faeces. As the rectal prolapse progresses, the rectum can prolapse out upon innocuous daily physical activities like standing or walking or while coughing or sneezing. Patients may have to push it back manually. Although it may only produce an uncomfortable sensation at first, symptoms can appear soon after. At an advanced stage, the rectum may permanently remain suspended outside the anal orifice. Other symptoms of rectal prolapse are:

• Pain
• Constipation
• Fecal incontinence
• Discharge of mucus
• Ulceration of the prolapsed rectal mass
• Rectal bleeding

Risk factors of rectal prolapse in adults are:

• Increased intra-abdominal pressure (for example, constipation, diarrhea, benign prostatic hypertrophy, pregnancy, severe or chronic cough due to chronic obstructive pulmonary disease, cystic fibrosis, whooping cough, etc)
• Age (advanced age causes the anal sphincter and pelvic floor muscles to become lax)
• Females (pregnancy and childbirth can injure nerves and hamper supportive structures like pelvic floor muscles and hysterectomies also increase risk)
• Diabetes
• Previous surgery
• Pelvic floor dysfunction
• Parasitic infections (for example, amoebiasis or schistosomiasis)
• Neurological disease (for example, previous lower back or pelvic trauma, lumbar disc disease, cauda equina syndrome, spinal tumours or multiple sclerosis)
• Psychiatric disease

Risk factors of rectal prolapse in children are:

• Congenital conditions like: 
  • Cystic fibrosis
  • Ehlers-Danlos syndrome
  • Hirschsprung's disease
  • Congenital megacolon
  • Malnutrition
  • Rectal polyps
• Natural differences in rectal anatomy:
  • Rectum is positioned lower than other pelvic organs
  • More vertical course of the rectum along the sacrum and coccyx pelvic bones
  • Looser attachment of the mucosa to the muscular pelvic floor
  • A more mobile sigmoid colon in children (provides lesser structural support to the rectum)
  • Underdeveloped levator ani muscles of the pelvic floor
  • Underdeveloped Houston valves

Following are the causes of rectal prolapse in adults: 

• Increased intra-abdominal pressure:
  • Constipation
  • Diarrhea
  • Straining to pass urine due to a swollen prostate gland
  • Pregnancy
  • Persistent cough
• Mental health conditions associated with constipation, such as:
  • Depression
  • Anxiety (as in irritable bowel syndrome).
  • A side-effect of medicines used to treat psychiatric disorders
• Injuries from previous operations (or other trauma) to the:
  • Anal sphincter (the opening of the back passage)
  • Nerves (can be commonly compressed due to a prolapsed intervertebral disc)
  • Muscles of the pelvic floor (very common with childbirth)
• Parasitic infections of the gut like:
  • Schistosomiasis 
  • Amoebiasis, etc. 
• Neurological disorders can cause abnormalities in the regular rhythmic movements of peristalsis in the intestines, increasing the risk of intussusception:
  • Previous lower back trauma or injury
  • Previous pelvic trauma
  • Lumbar disc disease
  • Cauda equina syndrome
  • Spinal tumours
  • Multiple Sclerosis, etc. 

Causes of rectal prolapse in children: Children between 1 to 3 years of age are at an added risk of developing rectal prolapse due to their natural anatomical differences and also because of various congenital conditions, disorders and anomalies like:

• Cystic fibrosis
• Ehlers-Danlos syndrome
• Hirschsprung's disease
• Congenital megacolon
• Malnutrition
• Rectal polyps

Some other conditions can closely mimic rectal prolapse. Examples are:

• Hemorrhoids: Also known as piles, haemorrhoids are swollen veins present in the rectum which prolapse outward. Both conditions can present as lumps that appear with bowel movements and can reduce afterwards or remain suspended outward. Haemorrhoids are generally noticed by the patient as blood in the stool. Clinical examination is necessary to differentiate between the two. 
• Rectal polyp: Another cause for the appearance of a lump or protuberance at the anal opening is a rectal polyp. They usually don’t present with many symptoms and are often harmless. Sometimes, they can lead to cancer. 

The doctor begins by taking a complete medical history, paying special emphasis to past medical history that could have raised intra-abdominal pressure or damaged the support mechanism of the rectum. Additionally, based on patient-reported signs and symptoms, the correct diagnosis is arrived at by excluding differential diagnoses.

Following this, a thorough physical examination is conducted. Neurological examination is essential to diagnose possible underlying causes like neurological diseases or nerve damage. A digital rectal examination will be carried out to examine the protruding mass, look for any ulceration or bleeding, anal sphincter tone and to differentiate from other causes of rectal lumps. Additionally, the patient may be asked to squat on the floor in order for the doctor to examine the rectal prolapse better.

Following investigations may be required in the case of rectal prolapse:

• Blood glucose levels: Diabetes, especially in the older population, is a risk factor for rectal prolapse.
• Stool examination: To detect blood in stool and even possible parasitic infection. Components of it include:
  • Visual inspection of stool specimen 
  • Stool microscopy
  • Stool culture and sensitivity testing 
• Colon visualisation studies: These investigations are performed clinically prior to surgery and in order to check the colon up to varying lengths for ulcers. These investigations can include:
  • Barium enema
  • Proctosigmoidoscopy
  • Colonoscopy 
• Anal physiology tests: These special tests can help differentiate between partial and complete rectal prolapse. Investigations include:
  • Defecography
  • Anal manometry
  • Continence tests
  • Electromyography of the anal sphincter and the pelvic floor
  • Nerve stimulation tests
• Radiological imaging studies: They can be useful to elucidate the underlying causes of chronic constipation like toxic megacolon.
• Other special investigations: 
  • Sweat test: Investigation of choice for diagnosing cystic fibrosis 

Surgical treatment: Although the decision to surgically correct rectal prolapse can be delayed if the patient’s lifestyle is not hampered, the prolapse will continue to gradually progress. Thus, surgery is the definitive treatment for rectal prolapse.

Surgery for adults:

• Emergency rectosigmoidectomy: In case the prolapse can not be reduced and the blood supply of the rectum gets cut off, the affected portion becomes dead. However, gangrene can set in and affect the whole bowel. Therefore, an emergency procedure is done to remove the rectum and part of the adjoining colon. 
• Excessive mucosal excision: In case of a partial prolapse, where only the mucosa is involved, only the excessive overhanging part can be excised.

Broadly two approaches can be adopted to pull the rectum up and attach it back in place:

• Rectopexy or abdominal surgery: The rectum is pulled up through the abdomen and fixed in place.
• Perineal surgery: The overhanging bowel (rectum) is excised either via a wire loop (Thiersch’s procedure) or by making small cuts in the bowel loop lining to help bunch it up and reduce its length (Delorme’s resection).

Surgery for children: Surgical treatment is reserved for children under four years of age who have been on conservative management for over a year without satisfactory results.

Non-surgical conservative management:

• Digital reduction of prolapse; local perianal anaesthetic might be necessary if it’s too painful to do so otherwise. Use of a water-soluble lubricant before the reduction is advisable in children.
• Avoiding and treating constipation: Chronic constipation, and thus repeated straining, can precipitate or aggravate a rectal prolapse. Following measures may help:
  • Drinking plenty of fluids
  • High-fibre diet
  • Laxatives
• Subcutaneous circumanal rubber ring: A ring-shaped device is often fitted in elderly patients who are unfit for surgery. However, prolapse can recur due to improper fitting. 

(Read more: How to get rid of constipation)

Following are the complications that could occur because of rectal prolapse:

• Mucosal ulceration
• Necrosis of the rectal wall
• Bleeding and dehiscence at the anastomosis (most common postoperative complications)
• Postoperative recurrence (rate of 20%) regardless of the operative procedure

Although not all risk factors for rectal prolapse are modifiable, avoiding and adequately treating constipation (a very common cause of increased intra-abdominal pressure as well as cause for straining during bowel movements) can reduce the chances of it. Constipation can be prevented by:

• Making high-fiber foods a part of your regular diet, including fruits, vegetables, bran and beans
• Reducing the amount of processed food in your diet
• Drinking plenty of water and fluids every day
• Exercising most, if not all, days of the week
• Managing your stress with meditation or other relaxation techniques

In the elderly population, the prognosis of rectal prolapse is highly variable and depends on the underlying cause, age, sex and the overall health status of the patient.

In the case of children under the age of three, most rectal prolapses only require non-surgical supportive therapy which culminates in complete resolution. However, in older children, the prognosis worsens with advancing age. Some children will continue to have rectal prolapse well into adulthood, especially if they develop it for the first time after three years of age.