It is uncommon for an anal fistula to heal spontaneously. In most cases, surgery is required to treat the condition. The type and technique of surgery will depend on the classification and situation of the fistula.
The only non-surgical treatment for anal fistula that is currently in use is fibrin glue. This involves an injection of the glue into the fistulous tract to approximate the sides closely together and prevent the space from persisting. Eventually the cells from the surrounding tissue will grow into the glue and the tract will be obliterated.
Many patients may prefer this method because it is a safe and painless procedure. However, it is less effective than surgical techniques. Some research has suggested that the majority of patients treated by this technique have complications or recurrence within 16 months of treatment.
Rationale for Surgery
The aim of surgical treatment is to heal the fistula without causing damage to the sphincter muscles. Such damage could lead to future complications such as bowel incontinence. The procedure is typically carried out under general anesthesia, although local anesthesia may be appropriate in some patients.
Prior to performing a surgical procedure on an anal fistula, it is necessary to determine the type. These include:
- recto-vaginal fistulae
This will enable the adoption of the best approach in order to achieve the optimum results for the procedure.
Subcutaneous or submucosal fistulae may be treated by fistulotomy. This refers to a simple probing of the fistula tract, without excision.
For other types of fistulae, the medial opening of the fistula needs to be identified exactly. This may be using diagnostic techniques such as endosonography. Some surgeons may freshen and approximate the edges of the fistula tract to improve healing and get better end-results.
Surgical Technique: Fistulotomy
The most common and effective type of surgical procedure for anal fistula is a fistulotomy, which accounts for approximately 90% of fistula surgery.
In this procedure, an incision is made along the whole length of the fistula, from the internal to the external opening. Depending on the location, a small portion of the anal sphincter may need to be cut to gain access to the fistula.
Once it has been opened, the tract is scraped thoroughly, the contents of the fistula are flushed out, and it is left open. In most cases the area will heal within 4-8 weeks to form a flat scar. With more complex fistulas, the tract may sometimes have to be laid open in parts instead of all at once.
Surgical Technique: Seton
A Seton is a piece of surgical thread or thin rubber that is left in the fistula tract to keep it open for a few weeks, to allow it to drain completely before closing. Its ends are brought out through the anus and tied, to keep it in place. By enabling proper drainage of the tract, it prevents fistula extension, brings down the inflammation and allows for scar formation inside the tract. This may later be removed and other surgical techniques used to correct the fistula permanently.
This technique is a good option for patients who have a high risk of bowel incontinence following surgery, due to the close proximity or involvement of the anal sphincter muscles. It is sometimes used with successively tighter setons in order to slowly erode the fistula wall and lay it open, without dividing the sphincter.
Surgical Technique: Advanced Flap
For a complex procedure, or for patients with a high risk of bowel incontinence following conventional fistulotomy, the advanced flap surgical technique may be a good option. This involves advancing a piece of tissue or skin, called the advancement flap, from the rectum or around the anus. The flap is then attached to the fistula opening after healing to assist healing. It does not require dividing the sphincter.
Surgical Technique: LIFT
The ligation of the intersphincteric fistula tract (LIFT) procedure is a promising new technique for the treatment of fistulas that pass through the anal sphincters. The fistula is entered through the skin, the anal sphincters are pushed apart and the part between them is laid open between ligatures to allow it to heal. It is a non-sphincter-dividing technique.
Surgical Technique: Bioprosthetic Plug
A cone-shaped plug of animal tissue called a bioprosthetic plug can also be used to fill the internal opening of the fistula. This is kept in place with stitches. Since it does not seal off the opening completely, it allows the fistula to continue draining. Eventually, new tissue grows around and into the plug and the tract is closed.
This technique is associated with a greater risk of complications such as pain, formation of an abscess or plug displacement.
Other associated procedures used in anal fistula surgery
Some fistulas are so deep or complex as to require multiple procedures. In between, a colostomy may be needed to handle defecation while the anal sphincter is healing. In other cases, muscle tissue may need to be grafted into the fistula tract so as to fill it up and ensure its complete obliteration.
Recovery Following Surgery
Complications of surgery include infection, recurrence and bowel incontinence. Patients are likely to suffer from some pain following the surgical procedure. This may be eased with analgesics and medications to reduce stool impaction, such as fiber and bulk laxatives.
Patients should take some medical leave in order to have some time away from work. This time following the surgery should be spent at home to recover. The time required for this will vary according to the type of surgery and individual case.