Anal fistula is the second of a double whammy, the first being a painful anal abscess. It should be promptly treated to prevent infection recurring on the same site.
An anal fistula is a small tunnel that persists after recovery from an anal abscess or an anal gland infection. It has one end opening on the inside of the anal canal, and the other on the outside, at the skin surface near the anus.
Some fistula first manifest as a small pimple around the anus – which bursts and heals, then recurs. They can also occur after an abscess has been treated by a small surgery. The wound may start to heal but never closes completely, creating a tunnel.
It is very important for the internal opening to close, or the fistula will not heal.
It can cause bleeding and discharge when passing stools, and can be painful. In some cases, an anal fistula causes persistent drainage, or, in cases where it is on the outside of the channel that is blocked, the result may be recurrent anal abscesses.
Among the typical symptoms are:
- A recurring cycle of pain, swelling, discharge and healing
- Constant, throbbing pain
- Skin irritation around the anus, including swelling, redness and tenderness
- Discharge of pus or blood
- Pain associated with bowel movements
Most of the time, diagnosis is straightforward, although for some complex fistula, further tests like endoanal ultrasound imaging or magnetic resonance imaging (MRI) may be necessary to ascertain the entire length of the fistula tract. This is also the case for surgical treatment, which is usually a straightforward procedure to open up the tunnel and allow the wound to heal from the inside.
It gets more complicated for deeper tracts, as a deep incision can cause damage to the muscles and result in incontinence later on. For these, more innovative options are explored, including:
- Ligation of Intersphincteric Fistula Tract (LIFT) – the tying off of the tunnel between the two layers of anal muscle.
- Fistula plug – filling up the tract with prosthetic material to let new tissues grow over.
- Fibrin glue – using surgical “glue” to seal up the tunnel.
- Seton – a stitch placed around the tract to drain the pus, allowing the muscle above it to heal; a second operation may be necessary later on.
- Video-assisted Anal Fistula Treatment (VAAFT) – one of the latest techniques, it lets the surgeon insert a video scope through the external opening to look at the entire tract all the way to the inner end. The internal opening is then closed, and the tract is cleaned out using a brush and a heater probe through the video scope. The added benefit of this approach is that there is no long cut over the skin.
The only cure for an anal fistula is surgery. Complications from this or any kind of surgery are a reality, so this procedure is best performed by a colorectal specialist to reduce the risk of losing bowel movement control. Most of the time, fistula surgery can be performed on an outpatient basis or with a short hospital stay.
If properly healed, the problem will usually not return. However, it is important to follow the directions of your doctor to prevent recurrence.