Anal fistula repair surgery

What is an anal fistula?

An anal fistula is an abnormal passage (tunnel) that forms between the lining inside the anus and the skin around the anus. It usually develops after an anal abscess: when the glands that produce fluid in the anus become blocked, bacteria can build up and form a pocket of infected tissue and fluid. Once the abscess drains, the channel that formed for drainage may stay open and become a fistula. Left untreated, fistulas can lead to recurrent infection, damage to the sphincter muscles (affecting continence), and in rare cases other complications—so repair is important.

Causes and diagnosis

The main cause is an anal abscess or blocked anal glands. Other causes can include Crohn’s disease, radiotherapy, injury or trauma, tuberculosis, and certain sexually transmitted infections. Diagnosis involves a physical examination of the area and sometimes use of a fistula probe to trace the tract. Imaging such as MRI, fistulography, or endoscopic ultrasound may be used to map the fistula and assess the sphincter muscles before planning surgery.

Treatment options

Fistula tracts need to be treated to prevent complications. The choice of operation depends on the fistula’s location, cause, and complexity. Options include:

• Fistulotomy: the fistula tract is laid open, infected tissue removed, and the wound allowed to heal.
• Ligation of the intersphincteric fistula tract (LIFT): for more complex or deep fistulas; the tract is identified between the sphincter muscles, ligated, and the infected tissue removed.
• Endorectal advancement flap: a flap of rectal lining is used to cover and seal the internal opening, which can reduce the amount of sphincter muscle that needs to be divided.
• Seton placement, fibrin glue, or collagen plug may be used in selected cases.

Symptoms and when to seek care

Common signs are swelling and tenderness around the anus, ongoing discharge of pus or blood (often with a bad smell), pain when sitting or moving, and sometimes difficulty controlling wind or stool if the sphincter is involved. The opening on the skin may close and reopen as the abscess builds and drains again. If you notice these symptoms, see a doctor; we can arrange examination and imaging so the fistula can be mapped and the right operation planned.

Prevention and aftercare

To reduce the risk of fistula or recurrence: maintain good anal hygiene, eat a fibre-rich diet, avoid straining when passing stool, stay well hydrated, and treat constipation promptly. After surgery we advise on wound care, diet (e.g. fibre, fluids), and follow-up; some procedures have a longer healing time but aim to preserve continence.