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Anal fistula repair

An anal fistula is a connection (opening) between the skin around the anus and the rectum.

Your care will be adapted to meet your individual needs and may differ from what is described here. It's important that you follow your surgeon's advice.

About anal fistula

Anal fistula usually occurs as a result of an infection or an abscess (collection of pus) in the anus. It can also be caused by conditions that affect the bowel such as inflammatory bowel disease or Crohn's disease.

There are different types of fistula. Some have a single connection running from the rectum to the skin. Others branch into more than one opening. Sometimes they cross the muscles that control the opening and closing of the anus (sphincter muscles).

Symptoms of anal fistula

Symptoms and signs of an anal fistula include:

  • pain and swelling in and around the anus
  • irritation of the skin around the anus
  • leakage of pus or blood
  • problems with continence

If you have these symptoms visit your GP.

Diagnosis of anal fistula

The treatment of anal fistulas is very complex. Your GP will usually refer you to a specialist colorectal surgeon (a doctor specialising in conditions that affect the bowel).

Anal fistula is usually diagnosed by physical examination of the anus and rectum. Your surgeon may do this by using a special telescope with a light on the end to see inside your rectum. Sometimes a fistula probe is used. This is a tiny instrument that is inserted through the fistula.

Your surgeon may also ask you to have a magnetic resonance imaging (MRI) scan. The scan can help find out how the fistula is linked to the sphincter muscles.

Surgery is usually the only option. The type of surgery you have will be tailored to your individual needs.

Preparing for your operation

Your surgeon will explain how to prepare for your operation. For example, if you smoke you will be asked to stop, as smoking increases your risk of getting a wound or chest infection, and slows your recovery. You may be given a laxative to take for a few days before your operation. This will help empty your bowels.

Anal fistula surgery is done under general anaesthesia. This means you will be asleep during the procedure. You will be asked to follow fasting instructions. Typically you must not eat or drink for about six hours before a general anaesthetic. However, some anaesthetists allow occasional sips of water until two hours beforehand. Usually, you will need to stay in hospital overnight.

At the hospital your nurse may check your heart rate and blood pressure, and test your urine.

Your surgeon will usually ask you to sign a consent form. This confirms that you understand the risks, benefits and possible alternatives to the procedure and have given your permission for it to go ahead.

Your nurse will prepare you for theatre. You may need to have a bowel washout (an enema). You may also be asked to wear compression stockings to help prevent blood clots forming in the veins in your legs. You may need to have an injection of an anti-clotting medicine called heparin as well as, or instead of, stockings.

About the operation

The operation usually takes 30 minutes. The exact procedure will depend on the type of fistula you have. Your surgeon will examine the fistula and decide the best way to treat it.

If the fistula is superficial, it can be "laid open". This is when the fistula is opened up so that it can heal from inside out. Sometimes it's necessary to leave a thread of, for example, suture material in the fistula tract. This is called a seton and may need to remain in place for some time. A dressing is usually worn over the fistula until it has fully healed.

Sometimes a special protein-based glue or plug is used to seal the fistula.

What to expect afterwards

You will need to rest until the effects of the anaesthetic have passed. You may need pain relief to help with any discomfort as the anaesthetic wears off.

You can begin to drink and eat, starting with clear fluids, when you feel ready.

On the morning after your operation, you will need to take a bath and soak off the dressing from your wound. It's normal to have some bleeding. Afterwards, your nurse will apply a new dressing.

You will need to have the wound re-dressed daily until it heals. Your nurse may arrange for a district nurse from your GP surgery to visit you at home. You will be given a letter to give to the district nurse. You will also be given a date for a follow-up appointment with your surgeon.

You may be prescribed a course of antibiotics and laxatives. If you are prescribed antibiotics it's important you finish the course.

You will need to arrange for someone to drive you home.

Recovering from anal fistula repair

If you need pain relief, you can take over-the-counter painkillers such as paracetamol or ibuprofen. Follow the instructions in the patient information leaflet that comes with the medicine and ask your pharmacist for advice.

General anaesthesia temporarily affects your co-ordination and reasoning skills, so you must not drink alcohol, operate machinery or sign legal documents for 48 hours afterwards.

The district nurse will visit you daily to change the dressing and to check that the wound is healing properly. You may be advised to have a bath or shower before your district nurse's visit. It may help to take a painkiller an hour beforehand, as having your dressing replaced can be uncomfortable. You may find it helpful to wear a sanitary pad to prevent any leakage from the wound staining your clothes.

You can go to the toilet with the dressing in place, but you should make sure that you carefully wash and dry the anal area afterwards.

You will need to take it easy during the first few days. Don't sit still for long periods or do too much walking. Follow your surgeon's advice about driving. You shouldn't drive until you feel you could perform an emergency stop without discomfort.

At your follow-up appointment, your surgeon will decide whether you need to continue with daily dressings. The time the wound takes to heal varies from a few weeks to a few months. You will also be given advice about going back to work and resuming other activities.

What are the risks?

Anal fistula operations are commonly performed and generally safe. However, in order to make an informed decision and give your consent, you need to be aware of the possible side-effects and the risk of complications of this procedure.


These are the unwanted, but mostly temporary effects of a successful treatment, for example feeling sick as a result of the general anaesthetic. You will feel sore and find it difficult to sit down. This should become easier after the first week.


This is when problems occur during or after the operation. Most people are not affected. The possible complications of any operation include an unexpected reaction to the anaesthetic, excessive bleeding or developing a blood clot, usually in a vein in the leg (deep vein thrombosis, DVT).

Specific complications of anal fistula operation are uncommon, but can include:

  • infection - this can result in an anal abscess and further surgery may be necessary
  • damage to the sphincter muscles - this may affect your bowel control and can lead to faecal incontinence
  • urgency and reduced ability to hold - you may find that you need to get to the toilet more quickly to open your bowels than you did before
  • re-occurrence - there is a chance that the fistula may come back

The exact risks are specific to you and differ for every person, so we have not included statistics here. Ask your surgeon to explain how these risks apply to you.

Further information

CORE (Digestive Disorders Foundation)


Zagrodnik D. Fistula-in-Ano. Emedicine. www.emedicine.com, accessed 7 February 2008

Related topics

Caring for surgical wounds

General anaesthesia