A fistula is an abnormal connection between two body surfaces. An anal fistula is an abnormal connection or a small
tunnel connecting the anal gland from which the abscess arose to the skin of the buttocks outside the anus. As long
as the internal opening does not close up, the fistula does not heal on its own.
Some fistulas start as a small pimple around the anus. This bursts and some pus, with or without blood, is
discharged. It then heals, but after a period of time, the pimple can form and burst again.
Another way that the fistula may manifest would be after an abscess has been drained. The wound nicely heals initially,
but even after a long time, does not close completely. In some cases, the skin heals, but soon, a swelling may appear
under the scar, and when the point in the scar bursts, pus comes out.
Most of the time, a history of repeated swelling and discharge can point towards the diagnosis of the abscess, and
examination of the area may even reveal the presence of the tract that leads from the skin into the anus. It is quite
common that fistulas may get misdiagnosed by the lay person
, as both can cause pain and some bleeding.
For some complex fistulas, additional imaging such as endoanal ultrasound (by putting a small ultrasound probe into the
anus) or magnetic resonance imaging (MRI) may be required to see the entire length of the fistula tract.
Surgery is almost always necessary to
cure an anal fistula
. The most straightforward fistula surgery is lay open
fistulotomy. This entails cutting a small portion of the anal sphincter muscle to open up the entire tunnel, which will
then heal from inwards to outwards.
For the deeper tracts, cutting open the muscle is not advisable as this may lead to incontinence. Some methods of
treatment would include:
- 1. Ligation of Intersphincteric Fistula Tract (LIFT) – this entails locating the tract between the
two layers of muscle, and separating and tying off the two ends of the tract.
- 2. Fistula plug – this uses a prosthetic material that fills up the entire tract and allows new
tissues to grow into the tract to replace the material, thereby closing up the tunnel.
- 3. Fibrin glue – this uses a “glue” to seal up the tunnel.
- 4. Seton – a seton is a stitch (suture) that is placed around the tract. This allows the pus in the
tract to come out along the seton, while at the same time, the seton slowly cuts through the muscle below and allows
the muscle above it to heal. A second operation may then be required to cut through the rest of the muscles once it
is safe enough to do so without risks of incontinence.
- 5. Video Assisted Anal Fistula Treatment (VAAFT) – this is one of the latest techniques available for
treatment of complex fistulas. It allows the surgeon to put a video scope through the opening to look at the entire
tract and follow it to the opening on the inside. The opening on the inside is then closed, and the tract is cleaned
out using the brush and a probe through the video scope. This has an added benefit that there will be no long cut
over the skin.
Although fistula surgery is usually relatively straightforward, the potential for complication exists, and is preferably
performed by a specialist in colon and rectal surgery. This operation needs to be done with care, as cutting too much
muscle will lead to loss of control of bowel movement. Most of the time, fistula surgery can be performed on an
outpatient basis – or with a short hospital stay.