An anal fissure is a tear or ulcer (open sore) that develops in the lining of the anal canal. Common symptoms of anal fissures include:
- a sharp pain or burning sensation when passing a stool (faeces )
- noticing bright red blood on toilet paper or on the toilet seat
The anal canal
The anal canal is the last part of the large intestine (colon), and is located between the rectum (a small pouch where stools are stored) and the anus (the opening through which stools are passed out of the body).
The anal canal is approximately 2.5-4cm (1-1.5in) long in adults and is lined by a thin layer of cells known as squamous epithelium cells. If this lining becomes damaged, an anal fissure can develop.
Type of anal fissure
Anal fissures can be classified as:
- primary – where there is no obvious cause why the anal canal was damaged
- secondary – where there is an obvious cause
It is difficult to prove for certain, but many experts believe that most cases of primary anal fissure occur when a person tries to pass a particularly hard stool which damages the anal canal.
Causes of secondary anal fissure include:
- pregnancy
- inflammatory bowel disease (IBD), which is a general term for conditions that cause inflammation of the intestines, such as ulcerative colitis and Crohn’s disease
Anal fissures can also be classified according to how long symptoms last. For example:
- acute anal fissure – where symptoms do not last longer than six weeks
- chronic anal fissure – where symptoms last longer than six weeks
How common are anal fissures?
It is hard to estimate exactly how common acute anal fissures are because many people do not report the symptoms to their GP.
However, most experts believe that acute anal fissures are relatively common. They affect both sexes equally and occur in people of all ages, including children. Younger adults between the ages of 20 to 40 are most likely to develop an anal fissure.
Chronic anal fissures are thought to be much less common than acute anal fissure, but they are certainly not rare. It is estimated that around 10% of people who visit a proctologist (a doctor who specialises in conditions that affect the rectum and anus) do so because they have a chronic anal fissure.
Outlook
The outlook for people with an acute anal fissure is generally good as the condition usually heals within a few weeks without the need for medical treatment. Switching to a high-fibre diet should also help to relieve symptoms and speed up the recovery time because the fibre makes it easier to pass stools.
The outlook for chronic anal fissures can vary from person to person. In some cases, the symptoms can be relieved by switching to a high-fibre diet. However, some cases may require medication to control the symptoms, and a small number of cases will require surgery.
