ANAL FISTULA

ANAL CANAL

What is an anal fistula?

An anal fistula is an abnormal connection or tunnel between your anal canal (back passage) and the skin of the bottom. It can often be seen as a small hole near your anus (the opening of your anal canal).

There are different types of fistulas. They can be a simple tunnel linking your anus and skin, or a complex network of tracts that branch off in different directions. Some fistulas run through the sphincter muscles which surround the anus and are responsible for maintaining bowel control.

What causes an anal fistula?

A fistula can form due to specific intestinal diseases, such as Crohn’s disease. But about half of fistulas develop from an infection around the anus which can result in an abscess. An abscess is a painful swollen area containing pus which is a yellowish/green liquid produced by infected tissue. An abscess in the anus can occur when a small gland just inside the anus becomes infected. When an abscess discharges its pus, it may cause a fistula. Fistulas can also form from a previous abscess that has not fully healed after being drained.

What are the symptoms of an anal fistula? The main symptoms are pain and leakage of pus (sometimes blood-stained) from the fistula. This leakage often relieves the pain. If an abscess is present, there will also be swelling around the anus.

How can a fistula be treated?

Fistulas very rarely heal by themselves and surgery is the only way to treat them. The surgery recommended for you will depend on the complexity of your fistula.

Surgery to treat a fistula is performed under anaesthetic, so you will not feel any pain.

The aim of the operation is to promote healing from the base of your fistula outwards to the skin surface. To do this, the infected tract is cut or ‘laid open’ to prevent unhealed pockets of infection from being trapped inside. If an abscess is present, this is cut open and drained first, before the fistula is laid open.

If you have a complex fistula, you may need more than one operation to assess and treat it.

Why should I have an operation?

As explained previously, surgery is the only way to treat your fistula. The surgery aims to relieve your symptoms, and remove the tracts and any infection. If you do not have the surgery, your fistula is unlikely to heal.

Are there any risks from the operation? The risk of complications for this type of surgery depends on where your fistula is. If the fistula is deep or complex, there may be an increased risk of damage to your anal sphincter muscles which are important for bowel control and continence. In most cases, surgery does not involve cutting a significant section of these muscles, so bowel continence is not at risk. However, you should be aware that any damage to the sphincter muscles can lead to a change in your ability to control wind or stool.

What if my sphincter muscles are involved in the fistula tract?

It is not always possible before surgery to tell whether your fistula runs through your sphincter muscles. Damage to these muscles can affect bowel continence. Therefore, if your fistula runs through these muscles, rather than cutting them, it is advised to put a stitch inyour fistula, called a ‘seton’. A seton is a thread that is inserted through the fistula tract, out of the bottom and then tied in a knot outside. This allows the infection to drain and heal, without damaging your sphincter muscles.

Part of your fistula that does not involve the sphincter muscles, and then insert a seton for the section that lies within the sphincter muscles. Therefore, you may end up with both a wound and a seton.

Recovering after anal fistula operation 

Leaving hospital 

If you have had your operation for fistula in ano, you will be able to leave hospital on the same day as your operation. You will need a friend or family member to travel home and stay with you for at least 24 hours after your surgery.

Will I have a dressing? 

You will have a dressing over your wound. If you do, please remove this in a bath the day after your surgery. You may need to give the dressing a gentle pull to take it off. It is possible that your wound will bleed, so do not be alarmed if this happens

Your surgeon will ask you to ‘digitate’ your wound. This involves running a finger along your wound to prevent the top layer of skin from healing too quickly. This may be uncomfortable but can help to prevent your fistula from recurring. If you do not wish to do this yourself or cannot reach the area, then a family member or a friend can do it.

What is Seaton?

A seton is a thread that is inserted through the fistula tract, out of the bottom and then tied in a knot outside. This allows the infection to drain and heal, without damaging your sphincter muscles. If you have had a seton stitch inserted, you may find that some mucus (thick, slippery fluid) leaks out of the wound. This is normal. You may wish to wear a pad in your underwear and bathe more often, as the mucus can cause the surrounding area to become sore and itchy.

Will I have any pain? 

As with all surgery, you should expect some discomfort. It can be quite painful for the first couple of days and it may seem like it gets worse before it starts to feel more comfortable again, but the pain will ease.

Tablets to go home with

Painkillers. It is important that you take your prescribed painkillers regularly to keep you as comfortable as possible. However, the tablets are not compulsory and if you have little pain you may not need to take them.

Antibiotics. We may give you a course of antibiotics to prevent infection and reduce your pain. You must not drink alcohol while you are taking the tablets or for 48 hours after you have finished the course. Mixed with alcohol, these tablets can cause unpleasant reactions such as nausea, vomiting, flushing of the face, headaches and palpitations.

Laxatives. These medicines will encourage bowel movement and help to keep your stool soft after the operation. You may not need to take laxatives after your operation .

What should I expect after toilet? 

You may have some discomfort and a little bleeding the first time you open your bowels. However, you should open them normally after the operation when you get the urge to do so. It is a good idea to take a dose of your painkillers about 15 – 20 minutes before you open your bowels, to reduce the discomfort.

Keeping the wound site clean 

It is important to keep the area of the operation clean and we recommend that you gently bathe your wound in a warm bath each day, if possible. This may also help with your pain. Do not use soap, or put salt or any perfumed products in the water until your wound has healed, as these could irritate your wound site.

If you can, try to wash the area or use alcohol-free wet wipes to clean it after each bowel movement.

When can I return to work and normal activities? 

Most people take a few days off work, but this depends on how you feel and how active your job is. Do as much as you feel able to, but avoid any strenuous activity such as lifting, exercise or running for 2 week.

You should not go swimming until your wound has healed.

Will my anal fistula return? 

Anal fistulas can be complex problems to treat and heal. This is why it is important that you attend your follow-up appointments. At this appointment, doctor will check your wound and/or seton stitch, and will discuss with you whether you need further surgery.​