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Anal Fissures

What is an anal fissure?
An anal fissure is a tear of the lining at the edge of the anus. This tear is usually secondary to excessive straining during bowel movement or repeated bowel movements such as during a "diarrhoea" episode. It can happen to anyone, irrespective of gender or age.
Anal fissures used to be classified as either acute (fresh tears of a few days duration) or chronic (fissure of more than 6 weeks with physical features of scar formation). However, this time-based classification is irrelevant as it does not help in patient management. Colorectal surgeons now determine the treatment based on the visual features of the anal fissure as well the patient's underlying medical problem.
What are the symptoms?
The main symptom is pain during defaecation. It has been described as if “passing of broken glass”. The pain may last for several minutes to hours after the bowel movement. Anal fissures usually appear at the front (toward the vagina or base of scrotum, depending on gender) and back (toward the tail bone) edges of the anal verge which are referred to as the 12 and 6 o’clock positions by doctors. It is usually singular but infrequently appears at multiple sites.
Some other symptoms and signs are listed below.
  1. Bleeding – small amount, usually seen on cleaning the anus
  2. Blood streak coating the stools
  3. Skin tag at the anal verge
  4. Itching around the anus
What causes anal fissure?
Anal fissures can be caused by trauma to the anus. The most commonly associated causes are:
  1. Chronic constipation
  2. Excessive straining during bowel movement
  3. Prolonged or repeated diarrhoea
  4. Anal sex, anal stretching
Occasionally, an anal fissure forms secondary to an underlying medical problem such as:
  1. Post-operative scarring in the anorectal region
  2. Crohn’s Disease and Ulcerative Colitis Colitis (Inflammatory Bowel Diseases)
  3. Anal cancer or Melanoma
  4. Infections such as Tuberculosis
  5. Sexually transmitted diseases (including syphilis, gonorrhea and HIV)
  6. Side effect of chemotherapy for cancer treatment
  7. Side effect of childbirth
How is anal fissure diagnosed?
An anal fissure is diagnosed by visualizing the tear on clinical examination of the anus. A gentle digital examination of the anus may be attempted if pain is minimal. Usually, an anal probe is not used so as not to aggravate the anal pain. A colonoscopy or examination under anaesthesia is rarely recommended and is only offered if there is a strong suspicion of an underlying medical problem.
How is anal fissure treated?
The aims of treatment are two-fold. The first aim is to heal the fissure and the second aim is to identify and treat the underlying cause.
Healing the fissure
A patient is usually prescribed a combination of stool softeners/ laxative, oral painkillers and anal ointment to facilitate easier bowel movement and avoid aggravating the fissure. A topical medication, such as glycerin trinitrate, can be used to aid healing.
If a fissure has become chronic, surgery may be necessary. It is important to remember that more than 90% of anal fissures will heal without requiring surgery.
Treating the underlying cause
Once a specific underlying cause is identified, it must be addressed otherwise the anal fissure will recur. The treatment of each cause is individualized.
If the patient suffers from constipation, this must be treated concurrently with the prescribed treatment to heal the fissure. Dietary advice and good toilet habits are essential. This is to prevent recurrence of the anal fissure. Similarly, if the patient is suffering from diarrhoea, it must be controlled. Patients suffering from inflammatory bowel diseases must have treatment to control their condition otherwise the anal fissure will not heal.
Do I need any tests before surgery?
Your doctor may request for some tests before surgery if there is a suspicion that there is an underlying medical problem. This may involve gastrointestinal endoscopy and anorectal physiology studies. Endoscopy is used to rule out medical conditions affecting various parts of the bowel including the stomach, small intestine and colon. Anorectal physiology studies are warranted if there is a dis-coordinated bowel movement pattern which can be corrected by physiotherapy.
Surgery for anal fissure
If an anal fissure persists despite medication, surgery is aimed at reducing the anal muscle pressure to improve blood circulation to the fissure. Very often, there is persistently raised anal muscle pressure due to muscle spasm. This procedure is termed “lateral internal anal sphincterotomy”.
The procedure is performed under light general anaesthesia or lower body anaesthesia as a day surgery procedure. The surgeon cuts a small portion of the lower internal anal sphincter (without risking anal incontinence) and that should allow the anal fissure to heal spontaneously. Recurrence of anal fissure after surgery is rare (less than 10%).
In cases of recurrent anal fissure after previous surgery, a surgeon may have to perform an “advancement flap” surgery to cover the affected fissure with healthy tissue.
What do I need to look out for after surgery?
The patient will have minimal pain even on passing motion. There is a small wound at the edge of the anus after surgery. There may be a small amount of blood stained discharge from the wound for a few days and the wound heals over in 1-2 weeks. Any stitches used are non-permanent and dissolve spontaneously.
Some potential complications to watch out for include wound infection, wound bleeding and anal incontinence. The likelihood of any complication is low.
A wound infection can occur if blood collects under the stitches in the wound and get infected during bowel movement. If that happens, you will need drainage of the infection and antibiotics. Rarely, a small blood vessel that had sealed during surgery re-opens a few days later and bleeds. You may need to have stitching of the vessel if the bleeding does not stop with pressure dressing. Neither of these complications are life-threatening.
Losing control of bowel movement is a nightmare to both patient and surgeon. Even though the risk is very small, it is difficult to treat once it occurs. That is why surgery is only offered if medical treatment fails.
How do I prevent recurrence of anal fissures?
If an underlying medical condition is identified, it is important to get it treated to prevent recurrence of anal fissure. For patients who develop anal fissures due to chemotherapy, it is unlikely to recur after chemotherapy is completed.
If there is an abnormal bowel movement pattern diagnosed, this should be corrected to prevent recurrence of anal fissure as well as other related problems. This can be done through a combionation of medication, dietary advice and pelvic floor physiotherapy (if needed).
If you have feedback or would like to know more about treatment for these conditions, feel free to contact us or make an appointment.