What is an anal fistula?
An anal fistula is an abnormal connection or tunnel between the anus and the skin outside the anus. It can occur spontaneously but is more commonly the result of a perianal abscess. Typically, a blocked anal gland leads to the formation of a perianal abscess, which may subsequently develop into an anal fistula.
Other, less common causes of anal fistulas include Crohn’s disease, tuberculosis (TB), or underlying cancer. Anal fistulas are usually benign but often require surgical intervention to resolve.
Symptoms
- Patients most commonly report discharge or leakage of pus, blood, fecal matter, or mucus from the anus or perianal region.
- Perianal pain or discomfort may occur if an infection remains undrained.
- A small opening or hole may be visible on the skin around the anus.
Treatment
The primary goal of treating anal fistulas is to preserve baseline continence. To achieve this:
1. Acute Management
- Your surgeon will drain any underlying infection or pus in the acute setting.
- A seton (either a rubber band loop or a thin, rope-like material) is placed in the fistula tract to ensure adequate drainage of the infection.
2. Definitive Treatment (once the infection is controlled):
- Fistulotomy:
- This involves cutting the muscle involved in the fistula tract to allow healing by secondary intention.
- The success rate for this procedure is 90–95%.
- Patient selection is crucial. Surgeons can assess sphincter function through anal manometry studies and evaluate the extent of sphincter involvement using endoanal ultrasound to ensure continence is preserved.
- Mucosal Advancement Flap (MAF) or Ligation of Inter sphincteric Tract (LIFT):
- These procedures are offered to patients with significant sphincter involvement who are unsuitable for fistulotomy.
- Cutting Seton:
- A braided seton is secured in the fistula tract. Over time, the body gradually migrates the seton, reducing sphincter involvement. The patient may then become eligible for a fistulotomy.
- Lifelong Seton:
- Some patients may tolerate a seton indefinitely to avoid surgical risks affecting continence.
- The seton needs to be replaced every 6–12 months, which can be done in the operating theatre or the consulting room.
