What is Fistula?

Anal fistula is the medical term for an infected tunnel that develops between the skin and the muscular opening at the end of the digestive tract (anus). Most anal fistulas are the result of an infection in an anal gland that spreads to the skin. Surgery is usually needed to treat anal fistula.

Causes

Diseases

Inflammatory bowel disease in the form of Crohns disease, but not ulcerative colitis, are the leading causes of anorectal, enteroenteral, and enterocutaneous fistulas. A person with severe stage-3 hidradenitis suppurativa will also develop fistulas.

Medical treatment

Complications from gallbladder surgery can lead to biliary fistula. Radiation therapy can lead to vesico-vaginal fistula. An arteriovenous fistula can be deliberately created, as described below in therapeutic use.

Trauma

Head trauma can lead to perilymph fistulas, whereas trauma to other parts of the body can cause arteriovenous fistulas. Obstructed labor can lead to vesicovaginal and rectovaginal fistulas. An obstetric fistula develops when blood supply to the tissues of the vagina and the bladder (and/or rectum) is cut off during prolonged obstructed labor. The tissues die and a hole forms through which urine and/or feces pass uncontrollably. Vesicovaginal and rectovaginal fistulas may also be caused by rape, in particular gang rape, and rape with foreign objects, as evidenced by the abnormally high number of women in conflict areas who have suffered fistulae. In 2003, thousands of women in eastern Congo presented themselves for treatment of traumatic fistula caused by systematic, violent gang rape that occurred during the country's five years of war. So many cases have been reported that the destruction of the vagina is considered a war injury and recorded by doctors as a crime of combat.

Treatment

Treatment for fistula varies depending on the cause and extent of the fistula, but often involves surgical intervention combined with antibiotic therapy.

Typically the first step in treating a fistula is an examination by a doctor to determine the extent and path that the fistula takes through the tissue.

In some cases the fistula is temporarily covered, for example a fistula caused by cleft palate is often treated with a palatal obturator to delay the need for surgery to a more appropriate age.
Surgery is often required to assure adequate drainage of the fistula (so that pus may escape without forming an abscess). Various surgical procedures are commonly used, most commonly fistulotomy, placement of a seton (a cord that is passed through the path of the fistula to keep it open for draining), or an endorectal flap procedure (where healthy tissue is pulled over the internal side of the fistula to keep feces or other material from reinfecting the channel). Treatment involves filling the fistula with fibrin glue; also plugging it with plugs made of porcine small intestine submucosa have also been explored in recent years, with variable success. Surgery for anorectal fistulae is not without side effects, including recurrence, reinfection, and incontinence.

It is important to note that surgical treatment of a fistula without diagnosis or management of the underlying condition, if any, is not recommended. For example, surgical treatment of fistulae in Crohns disease can be effective, but if the Crohns disease itself is not treated, the rate of recurrence of fistula is very high (well above 50%).

Western Medicine Treatment

There are several stages to treating an anal fistula:
Definitive treatment of a fistula aims to stop it recurring. Treatment depends on where the fistula lies, and which parts of the anal sphincter it crosses.

There are several options:

Doing nothing: a drainage seton can be left in place long-term to prevent problems. This is the safest option although it does not definitively cure the fistula.

Anal fistula after surgical treatment

Lay-open of fistula in ano: this option involves an operation to cut the fistula open. Once the fistula has been laid open it will be packed on a daily basis for a short period of time to ensure that the wound heals from the inside out. This option leaves behind a scar, and depending on the position of the fistula in relation to the sphincter muscle, can cause problems with incontinence. This option is not suitable for fistulas that cross the entire anal sphincter.

Cutting seton: if the fistula is in a high position and it passes through a significant portion of the sphincter muscle, a cutting seton (from the Latin seta, "bristle") may be used. This involves inserting a thin tube through the fistula tract and tying the ends together outside of the body. The seton is tightened over time, gradually cutting through the sphincter muscle and healing as it goes. This option minimizes scarring but can cause incontinence in a small number of cases, mainly of flatus. Once the fistula tract is in a low enough position it may be laid open to speed up the process, or the seton can remain in place until the fistula is completely cured.

Seton stitch: a length of suture material looped through the fistula which keeps it open and allows pus to drain out. In this situation, the seton is referred to as a draining seton. The stitch is placed close to the ano rectal ring which encourages healing and makes further surgery easy.

Fistulotomy: till anorectal ring

Colostomy: to allow healing

Fibrin glue injection is a method explored in recent years, with variable success. It involves injecting the fistula with a biodegradable glue which should, in theory, close the fistula from the inside out, and let it heal naturally. This method is perhaps best tried before all others since, if successful, it avoids the risk of incontinence, and creates minimal stress for the patient.

Fistula plug involves plugging the fistula with a device made from small intestinal submucosa. The fistula plug is positioned from the inside of the anus with suture. According to some sources, the success rate with this method is as high as 80%. As opposed to the staged operations, which may require multiple hospitalizations, the fistula plug procedure requires hospitalization for only about 24 hours. Currently, there are two different anal fistula plugs cleared by the FDA for treating ano rectal fistulas in the United States. This treatment option does not carry any risk of bowel incontinence. In the systematic review published by Dr Pankaj Garg, the success rate of the fistula plug is 65-75%.

Endorectal advancement flap is a procedure in which the internal opening of the fistula is identified and a flap of mucosal tissue is cut around the opening. The flap is lifted to expose the fistula, which is then cleaned and the internal opening is sewn shut. After cutting the end of the flap on which the internal opening was, the flap is pulled down over the sewn internal opening and sutured in place. The external opening is cleaned and sutured. Success rates are variable and high recurrence rates are directly related to previous attempts to correct the fistula.

FiLaC: (Fistula tract Laser Closure) is a novel techniqued developed using a newly invented radial emitting laser probe to destroy the fistula epithelium and to simultaneously obliterate the remaining fistula track. The aim is to gently remove the fistula channel without having to split it. Thus, any parts of the muscle are preserved and incontinence can be avoided to a very high extent. Excision of the fistula from the healthy tissue is not necessary. In order to eliminate the fistula tract as gently as possible, defined energy is being emitted radially into the fistula tract by using a novel fiber. The epithelialized tissue is being destroyed in a controlled way and the fistula tract collapses. This also supports and accelerates the healing process. A recent study involving 11 patients showed very promising results. Nine out of 11 fistulas showed primary healing (81.8%). Only one minor form of incontinence (limited soiling) was observed and no complications occurred.

LIFT Technique is a novel modified approach through the intersphincteric plane for the treatment of fistula-in-ano, known as LIFT (ligation of intersphincteric fistula tract) procedure. LIFT procedure is based on secure closure of the internal opening and removal of infected cryptoglandular tissue through the intersphincteric approach. Essential steps of the procedure include, incision at the intersphincteric groove, identification of the intersphincteric tract, ligation of intersphincteric tract close to the internal opening and removal of intersphincteric tract, scraping out all granulation tissue in the rest of the fistulous tract, and suturing of the defect at the external sphincter muscle. The procedure was developed by Thai colorectal surgeon, Arun Rojanasakul, The first reports of preliminary healing result from the procedure were 94% in 2007. Additional ligation of the intersphincteric fistula tract did not improve the outcome after endorectal advancement flap.