Anal Fistula Surgery

Small glands inside the anal canal can become blocked and infected, forming an anal abscess, a painful collection of pus near the anus. After the abscess bursts or is drained, a proportion of people are left with a fistula: a narrow tract lined with tissue that links the original gland inside the canal, the internal opening, with a small opening on the skin outside. Pus, blood or mucus drains from the outer opening, and when that opening closes the infection builds up again. Fistulas are described by their relation to the two rings of sphincter muscle. Low fistulas cross little or no muscle, while high, branching or horseshoe fistulas cross more of it. Anal fistula surgery aims to remove or close the tract completely and let the area heal while keeping as much sphincter function as possible. Fistulas linked to Crohn's disease, previous radiotherapy or recurrence after earlier surgery are called complex and need a tailored, often staged approach.

Surgery is recommended for almost every anal fistula that causes symptoms, because antibiotics and creams can calm infection but do not close the tunnel. Typical symptoms are persistent or recurring discharge that stains underwear, itching and soreness around the anus, a small lump or opening on the skin, and repeated abscesses that flare up and settle. An abscess is drained first as an urgent procedure, and the fistula is treated once the infection has settled. Investigation comes before the operation: the surgeon examines the area and, for anything other than a clearly simple fistula, arranges an MRI of the pelvis or an endoscopic ultrasound to map the tract and any branches. In Crohn's disease, treatment is planned jointly with gastroenterologists, because controlling the bowel inflammation with medicines matters as much as surgery, and a long-term seton is often preferred to cutting muscle. Fistulas with unusual features may also need a biopsy.

The operation starts with an examination under anaesthesia, during which the surgeon gently passes a probe along the tract to find the internal opening and judge how much muscle is involved. The technique then follows the anatomy. In fistulotomy, used for low fistulas, the tract is laid open along its length so that it heals from the base up. A seton is a soft thread or silicone loop placed through the tract and tied loosely; it drains infection and protects the muscle, either as a first stage or as a long-term solution. LIFT, short for ligation of the intersphincteric fistula tract, ties and divides the tract in the space between the two sphincter muscles. In an advancement flap, a flap of healthy rectal lining is moved down to cover the internal opening. Laser closure seals the tract from within using a thin probe. Most operations take about 20 to 60 minutes.

Most people with a confirmed anal fistula are candidates, but the right operation depends on the course of the tract, previous surgery, continence and conditions such as Crohn's disease, diabetes or smoking, which can delay healing. Before surgery, describe your bowel habit and any leakage honestly, because baseline continence shapes how much muscle can safely be divided. Imaging with MRI or endoscopic ultrasound is often arranged, and an anal manometry test may measure sphincter strength. If the fistula is actively infected, a seton may be placed first and the definitive repair done after about six to twelve weeks, which affects travel planning. Blood tests and a review of medicines, including blood thinners, are completed beforehand, and a small enema may be given on the day. International patients can start by sending previous operation notes and MRI scans, so the team can outline a likely plan and the number of visits before booking.

Most people go home the same day or the next morning. Pain is usually moderate and controlled with regular painkillers, and stool softeners prevent straining. Wounds after fistulotomy are left open to heal from the inside out, so some discharge and spotting are normal for several weeks. Warm shallow baths or rinsing the area after each bowel movement, with a light pad, keep it clean, and the team checks that the wound is healing from the base rather than closing over too early. Desk work is usually possible within one to two weeks, although complete healing can take about 4 to 12 weeks. For travel, plan about five to seven days near the hospital for a first wound check, and agree in advance who will review the wound at home. A staged treatment with a seton means a second trip, typically after a few months, which is worth planning from the start.

Anal fistula surgery is generally safe, but two outcomes need an honest discussion: the chance that the fistula returns and the chance of changes in continence. Fistulotomy heals most simple low fistulas, but because it divides some muscle it can cause minor leakage of wind or soiling, especially in women who have had vaginal births and in anyone with previous anal surgery. Sphincter-sparing methods such as LIFT, advancement flap and laser closure largely avoid cutting muscle, but they fail more often, so a further procedure may be needed. Complex and Crohn's-related fistulas often require several stages, and for some people the realistic goal is control of infection with a long-term seton rather than complete closure. Other risks include bleeding, infection, slow wound healing and a new abscess. An experienced colorectal team and acceptance of a staged plan when needed give the soundest basis for a good result.