Anal fistula
Overview
 
Anal fistula, or fistula-in-ano, is an abnormal connection between the epithelialised surface of the anal canal
Anal canal
The anal canal is the terminal part of the large intestine.It is situated between the rectum and anus, below the level of the pelvic diaphragm. It lies in the anal triangle of perineum in between the right and left ischioanal fossa....

 and (usually) the perianal skin.

Anal fistulae originate from the anal glands
Anal glands
The anal glands or anal sacs are small glands found near the anus in many mammals, including dogs and cats. They are not found in humans or other primates. They are paired sacs located on either side of the anus between the external and internal sphincter muscles. Sebaceous glands within the...

, which are located between the two layers of the anal sphincters and which drain into the anal canal
Anal canal
The anal canal is the terminal part of the large intestine.It is situated between the rectum and anus, below the level of the pelvic diaphragm. It lies in the anal triangle of perineum in between the right and left ischioanal fossa....

. If the outlet of these glands becomes blocked, an abscess
Abscess
An abscess is a collection of pus that has accumulated in a cavity formed by the tissue in which the pus resides due to an infectious process or other foreign materials...

 can form which can eventually point to the skin surface.
Encyclopedia
Anal fistula, or fistula-in-ano, is an abnormal connection between the epithelialised surface of the anal canal
Anal canal
The anal canal is the terminal part of the large intestine.It is situated between the rectum and anus, below the level of the pelvic diaphragm. It lies in the anal triangle of perineum in between the right and left ischioanal fossa....

 and (usually) the perianal skin.

Anal fistulae originate from the anal glands
Anal glands
The anal glands or anal sacs are small glands found near the anus in many mammals, including dogs and cats. They are not found in humans or other primates. They are paired sacs located on either side of the anus between the external and internal sphincter muscles. Sebaceous glands within the...

, which are located between the two layers of the anal sphincters and which drain into the anal canal
Anal canal
The anal canal is the terminal part of the large intestine.It is situated between the rectum and anus, below the level of the pelvic diaphragm. It lies in the anal triangle of perineum in between the right and left ischioanal fossa....

. If the outlet of these glands becomes blocked, an abscess
Abscess
An abscess is a collection of pus that has accumulated in a cavity formed by the tissue in which the pus resides due to an infectious process or other foreign materials...

 can form which can eventually point to the skin surface. The tract formed by this process is the fistula.

Abscesses can recur if the fistula seals over, allowing the accumulation of pus
Pus
Pus is a viscous exudate, typically whitish-yellow, yellow, or yellow-brown, formed at the site of inflammatory during infection. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collection of pus within or beneath the epidermis is known as a pustule or...

. It then points to the surface again, and the process repeats.

Anal fistulas per se do not generally harm, but can be very painful, and can be irritating because of the pus-drain (it is also possible for formed stools to be passed through the fistula); additionally, recurrent abscesses may lead to significant short term morbidity from pain, and create a nidus for systemic spread of infection.

Surgery is considered essential in the decompression of acute abscesses; repair of the fistula itself is considered an elective procedure which many patients elect to undertake due to the discomfort and inconvenience associated with a draining tract.

Symptoms

Anal fistulae can present with many different symptoms:
  • Pain
  • Discharge - either bloody or purulent
  • Pruritus ani
    Pruritus ani
    Pruritus ani is the irritation of the skin at the exit of the rectum, known as the anus, causing the desire to scratch. The intensity of anal itching increases from moisture, pressure, and rubbing caused by clothing and sitting...

     - itching
  • Systemic symptoms if abscess becomes infected

Diagnosis

Diagnosis is by examination, either in an outpatient setting or under anaesthesia (referred to as EUA - Examination Under Anaesthesia). The examination can be an anoscopy
Anoscopy
An anoscopy is an examination using a small, rigid, tubular instrument called an anoscope . This is inserted a few inches into to the anus in order to evaluate problems of the anal canal. Anoscopy is used to diagnose hemorrhoids, anal fissures , and some cancers.-Process:This test is usually done...

.

Possible findings:
  • The opening of the fistula onto the skin may be seen
  • The area may be painful on examination
  • There may be redness
  • An area of induration may be felt - thickening due to chronic infection
  • A discharge may be seen
  • It may be possible to explore the fistula using a fistula probe (a narrow instrument) and in this way it may be possible to find both openings of the fistula

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.

  • 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
    Fecal incontinence
    Fecal incontinence is the loss of regular control of the bowels. Involuntary excretion and leaking are common occurrences for those affected. Subjects relating to defecation are often socially unacceptable, thus those affected may be beset by feelings of shame and humiliation...

    . 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 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
    Fecal incontinence
    Fecal incontinence is the loss of regular control of the bowels. Involuntary excretion and leaking are common occurrences for those affected. Subjects relating to defecation are often socially unacceptable, thus those affected may be beset by feelings of shame and humiliation...

     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 – encourages healing and makes further surgery easy.
  • Fistulotomy
    Fistulotomy
    A Fistulotomy is the surgical opening of a fistulous tract. They can be performed by excision of the tract and surrounding tissue, simple division of the tract, or gradual division and assisted drainage of the tract by means of a seton; a cord passed through the tract in a loop which is slowly...

     - 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. Small intestinal submucosa stimulates the body to close the fistula from the inside out. 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.
  • LIFT Technique
    LIFT technique
    LIFT technique is the novel modified approach through the intersphincteric plane for the treatment of fistula-in-ano, known as LIFT procedure. LIFT procedure is based on secure closure of the internal opening and removal of infected cryptoglandular tissue through the intersphincteric approach...

    is a novel modified approach through the intersphincteric plane for the treatment of fistula-in-ano, known as LIFT (ligation of inter sphincteric 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, Colorectal Division Department of Surgery, Chulalongkorn University in Bangkok, Thailand. The fist reports of preliminary healing result from the procedure were 94% in 2007
  • VAAFT Technique: This technique involves use of an endoscope, i.e Fistuloscope and involves two stages. First the scope is introduced thru' external opening and to identify the internal opening where the light is reflected on the anal wall. This is the Diagnostic step. Then a suture [purse string] is taken around the internal opening so as to close it snugly. A semicircular stapler or linear stapler can be used also. Then the fistula tract is debrided with fistula brush and scrappings sent for HPE. A fibrin glue injected near the inner end[now closed] and coagulation of the whole wall is done with the electrode. Simultaneously, the scope is withdrawn and the therapeutic procedure is over.

Infection

Some patients will have active infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

 when they present with a fistula, and this requires clearing up before definitive treatment can be decided.

Antibiotics can be used as with other infections, but the best way of healing infection is to prevent the buildup of pus in the fistula, which leads to abscess formation. This can be done with a seton - a length of suture material looped through the fistula which keeps it open and allows pus
Pus
Pus is a viscous exudate, typically whitish-yellow, yellow, or yellow-brown, formed at the site of inflammatory during infection. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collection of pus within or beneath the epidermis is known as a pustule or...

 to drain out. In this situation, the seton is referred to as a draining seton.

See also

  • Pilonidal cysts/sinuses
    Pilonidal cyst
    A pilonidal cyst, also referred to as a pilonidal abscess, pilonidal sinus or sacrococcygeal fistula, is a cyst or abscess near or on the natal cleft of the buttocks that often contains hair and skin debris.-Etymology:...

    , another condition in which infected perianal "holes" or openings may appear
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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