see this might help you
What is it?
An anal fistula is a narrow tunnel running from the skin near the back passage and opening into the back passage higher up. It often shows up after there has been an abscess near the back passage. This can happen because the back passage is full of bugs that can fuel an infection, which then turns into an abscess (pool of thick pus).
The roof of the fistula is cut away. This changes it from a tunnel into a trench. The trench becomes shallower as it heals, and ends up as a flat scar after a month or two. The operation can either be done as a day case, which means that you come into hospital on the day of the operation and go home the same day, or as an inpatient case, which means spending one or two nights in hospital.
You can leave things as they are. This means that the fistula will carry on discharging. You may well get more painful abscesses. The condition is usually not dangerous, but can be a great nuisance. However, sometimes getting many abscesses over a long period of time can make you very ill and cause a generalised infection (sepsis) when you feel very week and have a lot of pain and a high temperature. This can potentially be very dangerous. Antibiotics do not make the track close off. Sometimes the tracks are very deep, and need more than simple coring out at a later date. The surgeon may only find this out when he examines you under anaesthetic. If this happens, he will talk to you about what to do next, after you wake up. Heat treatment and laser treatment do not work.
In general the operation is not particularly painful. But the final healing sometimes takes more than eight weeks. You should, however, be able to return to work before the wound has healed. We hope these notes will help you through your operation. They are a general guide. They do not cover everything. Also, all hospitals and surgeons vary a little. If you have any queries or problems, please ask the doctors or nurses.