The anus is an external opening through which faeces is expelled out of your body. There are a number of small glands inside the anus. These glands may sometimes get blocked and form an infected cavity called an abscess. Often, anal abscesses further develop into an anal fistula. An anal fistula is a small channel or tunnel that develops from the infected gland and opens out onto the skin near the anus.
Some fistulae have only one opening, while others are branched out into many openings. Fistulae may sometimes be connected to the sphincter muscles,the muscles that open and close the anus. The ends of the fistulae look like holes on the surface of the skin around the anus. Anal fistulas are commonly treated through surgery.
Signs and Symptoms
The commonly observed symptoms of an anal fistula include:
- Throbbing pain that may get severe when sitting
- Irritation of the skin around the anus
- Swelling, tenderness, redness
- Discharge of pus
- Pain during bowel movement
- Fever and fatigue
Your doctor may review your medical history and conduct a physical examination to find the opening of the fistula. This will help your doctor trace the path of the channel, which can usually be felt as a hard cord-like structure below the skin. A digital rectal examination (insertion of a gloved finger through your anus) may be performed to find the internal opening of the fistula, the presence of any branching and the functioning of the sphincter muscles. Further examinations may be performed with the use of a fistula probe (a tiny instrument inserted into the rectum) and a proctoscope (a lighted device). Your doctor may recommend an ultrasound, CT or MRI scan for complicated fistulae with many branches, to evaluate the exact position of the fistula channels.
As part of the pre-surgical process, you will be advised to stop smoking, fast for about 6 hours before the surgery, andyou will be given an enema an hour before the surgery to empty your lower bowel. Anal fistula surgery is performed under general anaesthesia.The type of operation depends on the position of the fistula.
Fistulotomy: The surgery involves cutting open the fistula across its whole length in order to flush out the contents. It heals into a flattened scar after 1 – 2 months.
Seton technique: The seton technique involves passing a surgical thread into the fistula tract and leaving it in place for several months or permanently. This helps to keep the tract open and drain the contents of the fistula. This may be considered if you are at a risk of incontinence (inability for you to control your bowel movements), because your fistula crosses your sphincter muscles.
Advancement flap procedures: This procedure is usually preferred if the fistula is complex or if you are at a high risk of developing incontinence. The fistula tract is removed.A small piece of tissue (advancement flap) is removed from the rectum or from the skin around the anus and attached over the opening of the fistula.
Bioprosthetic plug: A cone shaped plug is developed from human tissue. It is used to block the internal opening of the fistula andis sutured in place. The plug does not completely close the opening, allowing the fistula to drain.
After the surgical procedure, your doctor will discharge you from the hospital on the same day or after a few days based on your condition. It might take 6 weeks for the wound to heal completely. The doctor may prescribe painkillers, antibiotics and laxatives. You will be advised to carefully wash, clean and dry your anal area. You are advised not to sit for long periods and walk much until healing occurs.
Risks and Complications
Anal fistula surgery is generally safe with no major risks. However, like most surgeries, anal fistula surgeries may involve complications such as:
- Narrowing of anal canal
- Damage of sphincter muscles
- Re-occurrence of fistula
Your doctor will access your condition with utmost detail and recommend the best treatment option.