In this article
What is anal canal
The anus is the opening of the bowel at the back passage (anal canal). There are two rings of muscle, called the internal and external anal sphincters, around the anal canal. These muscular rings relax when you open your bowels. The internal sphincter remains contracted the rest of the time so that you do not pass faeces involuntarily (incontinence).
What is an anal fissure
The anal canal has a lining of skin. An anal fissure is a tear in this skin around the back passage. It is a common problem that causes severe pain, especially after a bowel movement and the pain can continue for several hours and often discourages bowel movements. It may also cause bleeding. This leads to pasm of the internal anal sphincter causing constipation, which makes the problem worse. This reduces the blood supply to the area and prevents healing. Then the fissure tend to stay sore for a long time and can come and go (chronic anal fissure).
What causes an anal fissure?
Common causes of anal fissure:
- Inherently high tone in the internal anal sphincter
- Passing large or hard stools
- Constipation and straining during bowel movements
- Chronic diarrhoea
- Inflammatory bowel disease such as Crohn's disease
Less common causes of anal fissures:
- Anal cancer
What are the symptoms of an anal fissure?
An anal fissure may cause one or more of the following symptoms:
- A visible tear in the skin around your anus
- A skin tag, or small lump of skin, next to the tear
- Sharp pain in the anal area during bowel movements
- Pain after bowel movements that can last up to several hours
- Atreaks of blood on stools or on toilet paper after wiping
- Burning or itching in the anal area
How is it diagnosed?
After listening to your medical history, your doctor will perform a digital rectal exam, which involves inserting a gloved finger into your anal canal, or use a short, lighted tube (proctoscope) to inspect your anal canal. The fissure can be a sign of another disorder, such as Crohn's disease. Therefore, your doctor may recommend further testing such as colonoscopy especially if your are being considered for surgery.
Treatment options are geared towards breaking the vicious cycle of anal sphincter spasms and reducing damage to anal canal during passing stools.
Eating more fibre and drinking more fluid helps you to pass soft motions and reduces the pain. Laxatives help you to pass soft motions, preventing unnecessary stretching of the anal canal. Local anaesthetic ointments can also be given to help the pain. These however, may not completely treat the underlying cause in most cases: too strong internal sphincter muscle tone.
Specific Non-Surgical Treatment
Glyceryl trinitrate (GTN) or diltiazem are ointments that can be applied to the skin at the back passage, helping to reduce muscle spasm and improve the blood supply. Studies show that this treatment heals around 2 in 3 anal fissures if given for eight weeks. Once the treatment is stopped, symptoms will return in about 1 in 8 people. Up to 2 in 5 people suffer headaches with the GTN ointment. Paracetamol taken at the same time usually helps. A small percentage of these people have to stop the treatment. Diltiazem ointment is not availabale in Sri Lanka
Botulinum toxin (BOTOX) can be injected into the sphincter muscle. It works by paralysing the muscle and so reducing the spasm and increasing the blood supply enough to allow the fissure to heal. The effects of the botulinum toxin last for three to six months, which is enough time for 2 in 3 fissures to heal. Incontinence is rare. The muscle returns to normal after three to six months. Infection at the injection site may happen (risk: less than 1 in 100).
Lateral Internal Anal Sphincterotomy
Lateral Internal Sphincterotomy is the gold standard in surgical management of anal fissures. Sphincterotomy simply means dividing the sphincter. The operation reduces the strength of muscle spasm, allowing increased blood supply and helping the fissure to heal.
The operation is usually performed under a general or spinal anaesthetic and takes about a quarter of an hour. You may also have injections of local anaesthetic to help with the pain after surgery. You may be given antibiotics during the operation to reduce the risk of infection.
The surgeon will make a small cut in the skin near your back passage. They will then cut the lower part of the internal sphincter muscle. This will relieve the spasm in the sphincter, allowing a better blood supply to heal the fissure. The surgeon will leave the wound open.