Anal Fistula Surgery

What does surgery for an anal fistula involve?

Under general anaesthetic the anal canal is examined and the external and internal openings are assessed.

It can be difficult at times to find the internal opening especially for high / complex fisultae

Once the internal opening is found, a gentle attempt at finding the tract is carried out and a fistula probe is passed through it.

If the tract is deemed low without much muscle involvement, a fistulotomy is performed. This is where all of the tissues from the skin and anal lining are cut down to the fistula probe in order to open the fistula and allow it to heal from inside out. This usually involves cutting part of the muscle(s). If too much muscle is divided, this can result in incontinence.

Therefore, if it is not clear how much muscle is involved or if there is obviously a lot of muscle involvement, a “seton” is placed through the tract guided by the fistula probe. This is a rubber band that stays in place keeping the tract open to prevent further complications of the fistula and facilitate further definitive surgery in the future.

What are the risks of surgery?

Bleeding is minimal and is usually associated with the raw area left behind after a fistulotomy.

Dividing too much muscle may result in faecal incontinence.

Surgery may be incomplete due to failure to identify the internal opening or the full extent of the fistula tract. This may require further imaging with an MRI or endo-anal ultrasound prior to embarking on more surgery.

Before surgery

Fast from midnight for a morning procedure OR from 7am for an afternoon procedure

You will be contacted by the hospital the day before your procedure to let you know what time to come in. This is usually 1-2 hours before your procedure to allow for the hospital check-in procedures.

You will be given a fleet enema about an hour before your procedure. This is to empty the rectum before operating.

After surgery

Minimal bleeding is expected after a fistulotomy.

Pain is mild to moderate and  is worst in the first few days. It is caused by the raw area left behind after fistulotomy. Some degree of pain or stinging may last a couple of weeks after surgery (especially following defecation).

If a seton is placed, there is usually minimal or no pain except where part of the tract is opened.

You should take regular Panadol (as long as there are no medical reasons for you not to take it such as an allergic reaction or liver disease).

Non-steroidal anti-inflammatory medication such as Neurofen and Voltaren can also help with pain and inflammation but should be taken on a full stomach. Take these for the first 3-5 days as required.

Stronger pain killers such as opioid anaelgesics (Endone, Codeine) may help in the first couple of days but should be taken sparingly as they can cause constipation which results in more pain when opening your bowels.

It is very important to maintain soft stools after haemorrhoid surgery. This is done by having an adequate intake of fluid and fibre (see Prevention of constipation) as well as taking regular Movicol (1 sachet 1-3 times a day).

Laxatives such as lactulose or coloxyl are not advisable as diarrhoea can worsen the pain. The aim is to have soft stools NOT loose watery stools.

Most patients are worried about opening their bowels especially for the first time after anal surgery. You should not let fear of pain stop you from opening your bowels as this will only make things worse by hardening the stools and causing a spasm of the anal muscles. You should take a strong pain-killer before or after opening your bowels. Getting into the shower and washing the area with water is also very helpful.

If you are finding it difficult to pass soft stools, it may be due to a spasm of the anal sphincter. This can be treated with topical Rectogesic ointment 2-3 times a day. This is an over-the-counter ointment that should be applied into the first 1-2cm of the anus. The easiest way to do this is to wear a disposable non-sterile glove (plastic food-handling gloves are ok) then apply 1.5cm of the ointment using your index finger.

These are an excellent way of relieving the pain especially after opening your bowels. You should put a handful of salt into a shallow bath of warm water and sit in it for 15 minutes. This is both soothing and acts as an antiseptic.

If the fistula is opened, regular daily dressings may be required for a short time. Most of the time, however, there are no dressings apart from a pad that collects the post-operative blood. You may need to wear a pad for a couple of weeks to prevent staining your underpants.

Ladies’ sanitary pads work well for this purpose and can be used by men and women.

Most patients can go home on the day of surgery.

Follow up with your surgeon is usually within 4 weeks of your operation. You will be given an appointment before leaving the hospital. If, however, your operation finishes after hours, you will need to contact the rooms for a follow up appointment.

After insertion of a seton, further imaging (with endo-anal ultrasound or MRI) may be required to determine how much muscle is involved. Future procedures will then be required for definitive management of the fistula.