Anal fissure

Faeces (poo) is temporarily stored in the rectum and expelled from the body via the anus. An anal fissure is a tear or split in the lining of the anus (anal mucosa). The symptoms and signs include pain when passing a bowel motion and bright red blood from the anus.

The problem is common in children younger than one year, and affects around eight out of 10 babies. A person’s susceptibility to anal fissures tends to decline with age. Common causes in adults include constipation and trauma to the anus (such as a difficult childbirth).

Around half of cases heal by themselves with proper self-care and avoidance of constipation. However, healing can be a problem if the pressure of passing bowel motions constantly reopens the fissure. Treatment options include surgery.

Symptoms of anal fissure

The symptoms and signs of an anal fissure may include:

• anal pain
• pain when passing a motion and for some time afterwards
• bright red blood from the anus
• blood on the surface of stools
• blood smears on the toilet paper.

Role of the anus

The anus permits bowel continence, which is voluntary control over the passage of bowel motions. Waste is massaged down the length of the large intestine by waves of muscular contractions (peristalsis). Once the excess water is removed, the waste is temporarily stored in the rectum. The rectum joins to the anus, which is a short tube containing a muscular ring (sphincter) that can be opened at will to allow the expulsion of faeces (poo). The membranous lining of the anus is called the anal mucosa. An anal fissure is a tear in the anal mucosa.

Causes of anal fissure

Some of the causes include:

• chronic constipation
• passing a dry, hard stool
• rough or excessive wiping of the anus after passing a motion
• diarrhoea
• inflammation of the anus and rectum
• Crohn’s disease
• scratching (as a reaction to pinworm infection, for example)
• anal injury
• pregnancy
• childbirth
• cancer of the rectum.

Complications of anal fissure

Anal fissures aren’t associated with more serious diseases, such as bowel cancer, although cancer of the anus may mimic an anal fissure. Some of the possible complications of an anal fissure include:

• Chronic anal fissure – the tear fails to heal. Over time, this can cause extensive scar tissue at the site of the fissure (sentinel pile).
• Anal fistulas – abnormal ‘tunnels’ join the anal canal to surrounding organs, usually other parts of the bowel.
• Anal stenosis – the anal canal becomes abnormally narrowed either due to spasm of the anal sphincter or contraction of the resultant scar tissue.

Diagnosis of anal fissure

An anal fissure is diagnosed using a number of tests including:

• physical examination
• inspection of the anus and rectum with a slender instrument (anoscope).

Treatment for anal fissure

Medical treatment for an anal fissure may include:

• pain-relieving medication
• laxatives
• anaesthetic creams
• nitroglycerin creams or Botox injections to relax the associated muscle spasm.
• surgery.

Surgery for anal fissures

Severe anal fissures need to be surgically corrected. The fissure and associated scar tissue is removed. Sometimes, a thin slice of muscle from the anal sphincter is also removed, as this helps the wound to better heal. (Cutting and suturing this muscle doesn’t interfere with the patient’s sphincter control.) The operation, called a lateral internal sphincterotomy, can be performed under local anaesthetic. Around nine out of 10 people will never experience another anal fissure.

Self-help for anal fissures

Be guided by your health care professional, but general suggestions include:

• Apply petroleum jelly to the anus.
• See your chemist for advice on ointments specific for anal pain.
• Take regular sitz (salt bath) baths, which involves sitting in a shallow bath of warm water for around 20 minutes.
• Use baby wipes instead of toilet paper.
• Shower or bathe after every bowel motion.
• Drink six to eight glasses of water every day.

Prevention of anal fissures

Many cases of anal fissures are caused by chronic constipation. Suggestions include:

• Eat a high-fibre diet.
• Drink plenty of water to help soften stools.
• Consider using a fibre supplement (such as Metamucil).
• Make sure to wipe gently after going to the toilet.

Where to get help

• Your GP (doctor)
• Pharmacist