An anal fissure is a tear or ulcer in the lining of the anal canal, the final part of the large intestine, starting from the rectum above and ending at the anal orifice. Anal fissures are relatively common, and are estimated to affect 1 in 10 people at some point throughout their lifetime.
Anal fissure can occur as a result of any circumstance that puts excessive pressure on the lining of the anus. Thus there are a variety of causes, which may include:
- Constipation with large or impacted stools
- Chronic or persistent diarrhea
- Inflammatory bowel disease (e.g. Crohn’s disease)
- Infections such as syphilis, herpes, HIV or tuberculosis
In some cases, there may be no clear, identifiable cause, and then it is referred to as idiopathic anal fissure.
The most obvious symptom of an anal fissure is a sharp pain during the passing of stools and a deep burning pain in the anal region for several hours after having a bowel movement. There may also be spasm of the circular muscle band or sphincter that keeps the anus closed or open according to one’s wish.
Some patients may also report bright red bleeding when they pass stools, which may be visible on the surface of the stool or on the toilet paper.
The diagnosis of anal fissures is usually made based on the reported symptoms, such as pain and bleeding when passing stools. In most cases, the fissure is also visible if the buttocks are pulled apart.
A digital rectal examination (DRE) involving the insertion of a well lubricated, gloved finger into the anus is used only if any condition causing these symptoms, other than an anal fissure, is suspected, because it can be quite painful with an anal fissure. If required, the application of anesthetic ointment for 10 minutes before the examination may help relax the tight opening. Other abnormalities can be ruled out with a DRE.
Anal fissures usually heal spontaneously within several weeks. However, there are several ways in which patients can aid the healing of the skin and deeper tissues, and prevent recurrence of the fissure.
Self-care tips include:
- Consuming adequate dietary fiber (from fruit, vegetables and whole grains)
- Staying hydrated with plenty of water
- Passing stools without delay when the urge presents
- Developing a regular bowel movement
- Exercising regularly (at least 30 minutes each day)
- Avoiding topical products containing fragrance or alcohol near the anal region
- Soaking the buttocks in a warm sitz bath regularly, 2-3 times a day
There are several medications that may be useful in the treatment of anal fissures, including:
- Analgesic medications (such as paracetamol or ibuprofen) to relieve pain
- Laxatives to reduce constipation and assist in easy and regular bowel movements
- Glyceryl trinitrate ointment applied topically to the anus to expand blood vessels
- Topical anesthetic applied topically to the anus to numb the area before passing stools
- Calcium channel blocker drugs applied topically to the anus to relax sphincter muscles
- Botulinum toxin injections to paralyze the sphincter muscles and prevent muscle spasms
Surgery is not required in most cases of anal fissure, which will heal spontaneously. In those patients who develop a chronic anal fissure, surgery may become inevitable, and is very effective, resulting in long-term cure in over 90% of these patients.
Two commonly performed surgical techniques include:
- Lateral sphincterotomy: an incision is made in the internal sphincter muscle to reduce the excessive tension which keeps the anus tightly closed, and so reduce the likelihood of fissure recurrence
- Advancement anal flap: uses healthy tissue from another area of the body to repair the anal fissure in cases where the fissure is complex
Both of these procedures may be appropriate to treat anal fissures in some patients. However, they are also associated with a small risk of bowel incontinence. They should, therefore, be reserved for patients in whom other treatment methods have been unsuccessful.
Reviewed by Dr Liji Thomas, MD.