Anal fistula is a chronic
abnormal communication between the
epithelial
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellula ...
ised surface of the
anal canal
The anal canal is the part that connects the rectum to the anus, located below the level of the pelvic diaphragm. It is located within the anal triangle of the perineum, between the right and left ischioanal fossa. As the final functional segment ...
and usually the perianal skin.
An anal fistula can be described as a narrow tunnel with its internal opening in the
anal canal
The anal canal is the part that connects the rectum to the anus, located below the level of the pelvic diaphragm. It is located within the anal triangle of the perineum, between the right and left ischioanal fossa. As the final functional segment ...
and its external opening in the skin near the anus.
Anal fistulae commonly occur in people with a history of
anal abscesses. They can form when anal abscesses do not heal properly.
Anal fistulae originate from the
anal glands, which are located between the
internal
Internal may refer to:
*Internality as a concept in behavioural economics
*Neijia, internal styles of Chinese martial arts
*Neigong or "internal skills", a type of exercise in meditation associated with Daoism
*''Internal (album)'' by Safia, 2016
...
and
external anal sphincter
The external anal sphincter (or sphincter ani externus ) is a flat plane of skeletal muscle fibers, elliptical in shape and intimately adherent to the skin surrounding the margin of the anus.
Anatomy
The external anal sphincter measures about 8 ...
and drain into the
anal canal
The anal canal is the part that connects the rectum to the anus, located below the level of the pelvic diaphragm. It is located within the anal triangle of the perineum, between the right and left ischioanal fossa. As the final functional segment ...
.
If the outlet of these glands becomes blocked, an
abscess
An abscess is a collection of pus that has built up within the tissue of the body. Signs and symptoms of abscesses include redness, pain, warmth, and swelling. The swelling may feel fluid-filled when pressed. The area of redness often extends b ...
can form which can eventually extend to the skin surface. The tract formed by this process is a fistula.
Abscesses can recur if the fistula seals over, allowing the accumulation of
pus
Pus is an exudate, typically white-yellow, yellow, or yellow-brown, formed at the site of inflammation during bacterial or fungal infection. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collection ...
. It can then extend to the surface again – repeating the process.
Anal fistulae ''per se'' do not generally harm, but can be very painful, and can be irritating because of the drainage of pus (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, importantly, create a starting point for systemic infection.
Treatment, in the form of surgery, is considered essential to allow drainage and prevent infection. Repair of the fistula itself is considered an elective procedure which many patients opt for due to the discomfort and inconvenience associated with an actively draining fistula.
Signs and symptoms
Anal fistulae can present with the following symptoms:
* skin maceration
* pus, serous fluid and/or (rarely) feces discharge — can be bloody or
purulent
Pus is an exudate, typically white-yellow, yellow, or yellow-brown, formed at the site of inflammation during bacterial or fungal infection. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collect ...
*
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. At worst, anal it ...
— itching
* depending on presence and severity of infection:
:*pain
:*swelling
:*tenderness
:*fever
:*unpleasant odor
* Thick discharge, which keeps the area wet
Diagnosis
Diagnosis is by examination, either in an
outpatient
A patient is any recipient of health care services that are performed by healthcare professionals. The patient is most often ill or injured and in need of treatment by a physician, nurse, optometrist, dentist, veterinarian, or other health care ...
setting or under
anaesthesia
Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), am ...
(referred to as
EUA or Examination Under Anaesthesia). The fistula may be explored by using a fistula probe (a narrow instrument). In this way, it may be possible to find both openings. The examination can be an
anoscopy
An anoscopy is an examination using a small, rigid, tubular instrument called an anoscope (also called an anal speculum). This is inserted a few inches into the anus in order to evaluate problems of the anal canal. Anoscopy is used to diagnose h ...
. Diagnosis may be aided by performing a fistulogram, proctoscopy and/or sigmoidoscopy.
Possible findings:
* The opening of the fistula onto the skin may be observed
* The area may be painful on examination
* There may be redness
* An area of
induration
A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, nails, and related muscle and glands. The major function of this sy ...
may be felt; thickening due to chronic infection
* A discharge may be seen
Classification
* Park's classification: This was done by Parks et al. from the UK in 1976, before
MRI
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...
or
endoanal ultrasound
Endoanal ultrasound is a type of medical investigation which images the structures of the anal canal.
It is used in the investigation of some anorectal symptoms, e.g. fecal incontinence or obstructed defecation.
See also
* Medical ultrasonograph ...
was available. It classified the fistula in four grades:
* St James University Hospital Classification: This was done by Morris et al. in the year 2000. This classification was improvement over Parks classification as it was based on MRI studies. It classified the fistula in five grades.
* Garg classification: This was done by Pankaj Garg in 2017. This classification is improvement over both Parks and St James University Hospital Classification. This was based on MRI studies and operative findings in 440 patients. It classified the fistula in five grades. The grades of this classification correlate quite well with the severity of the disease. Grade I & II are simpler fistulas and can be managed by Fistulotomy whereas Grade III-V are complex fistulas in which fistulotomy should be not be done. They should be managed by Fistula experts. Unlike Park's and St James University Hospital Classification, this correlation is quite accurate with Garg's classification. Therefore this new classification is useful to both surgeons and radiologists.
Types
Depending on their relationship with the
internal
Internal may refer to:
*Internality as a concept in behavioural economics
*Neijia, internal styles of Chinese martial arts
*Neigong or "internal skills", a type of exercise in meditation associated with Daoism
*''Internal (album)'' by Safia, 2016
...
and
external sphincter muscles, fistulae are classified into five types:
* Extrasphincteric fistulae begin at the
rectum
The rectum is the final straight portion of the large intestine in humans and some other mammals, and the Gastrointestinal tract, gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the s ...
or
sigmoid colon
The sigmoid colon (or pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about in length. The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus ''s ...
and proceed downward, through the
levator ani muscle
The levator ani is a broad, thin muscle group, situated on either side of the pelvis. It is formed from three muscle components: the pubococcygeus, the iliococcygeus, and the puborectalis.
It is attached to the inner surface of each side of t ...
and open into the skin surrounding the
anus
The anus (Latin, 'ring' or 'circle') is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, the residual semi-solid waste that remains after food digestion, which, d ...
. Note that this type does not arise from the
dentate line
The pectinate line (dentate line) is a line which divides the upper two-thirds and lower third of the anal canal. Developmentally, this line represents the hindgut-proctodeum
A proctodeum is the back ectodermal part of an alimentary canal. It ...
(where the
anal gland
Anal may refer to:
Related to the anus
*Related to the anus of animals:
** Anal fin, in fish anatomy
** Anal vein, in insect anatomy
** Anal scale, in reptile anatomy
*Related to the human anus:
** Anal sex, a type of sexual activity involving s ...
s are located). Causes of this type could be from a rectal, pelvic or supralevator origin, usually secondary to
Crohn's disease
Crohn's disease is a type of inflammatory bowel disease (IBD) that may affect any segment of the gastrointestinal tract. Symptoms often include abdominal pain, diarrhea (which may be bloody if inflammation is severe), fever, abdominal distension ...
or an
inflammatory process
Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molec ...
such as
appendiceal or
diverticular abscess
An abscess is a collection of pus that has built up within the tissue of the body. Signs and symptoms of abscesses include redness, pain, warmth, and swelling. The swelling may feel fluid-filled when pressed. The area of redness often extends b ...
es.
* Suprasphincteric fistulae begin between the internal and external sphincter muscles, extend above and cross the
puborectalis muscle
The levator ani is a broad, thin muscle group, situated on either side of the pelvis. It is formed from three muscle components: the pubococcygeus, the iliococcygeus, and the puborectalis.
It is attached to the inner surface of each side of the ...
, proceed downward between the puborectalis and levator ani muscles, and open an inch or more away from the anus.
* Transphincteric fistulae begin between the internal and external sphincter muscles or behind the anus, cross the external sphincter muscle and open an inch or more away from the anus.
These may take a 'U' shape and form multiple external openings. This is sometimes termed a 'horseshoe fistula.'
* Intersphincteric fistulae begin between the internal and external sphincter muscles, pass through the internal sphincter muscle, and open very close to the anus.
* Submucosal fistulae pass superficially beneath the
submucosa
The submucosa (or tela submucosa) is a thin layer of tissue (biology), tissue in various organ (anatomy), organs of the gastrointestinal tract, gastrointestinal, respiratory tract, respiratory, and genitourinary system, genitourinary tracts. It i ...
and do not cross either sphincter muscle.
Differential diagnosis
Other conditions in which infected perianal "holes" or openings may include
pilonidal cyst
Pilonidal disease is a type of skin infection which typically occurs as a cyst Intergluteal cleft, between the cheeks of the buttocks and often at the upper end. Symptoms may include pain, swelling, and redness. There may also be drainage of flui ...
.
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
internal
Internal may refer to:
*Internality as a concept in behavioural economics
*Neijia, internal styles of Chinese martial arts
*Neigong or "internal skills", a type of exercise in meditation associated with Daoism
*''Internal (album)'' by Safia, 2016
...
and
external anal sphincter
The external anal sphincter (or sphincter ani externus ) is a flat plane of skeletal muscle fibers, elliptical in shape and intimately adherent to the skin surrounding the margin of the anus.
Anatomy
The external anal sphincter measures about 8 ...
s it crosses.
* 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
Incontinence or Incontinent may refer to:
*Fecal incontinence, the involuntary excretion of bowel contents
*Urinary incontinence, the involuntary excretion of urine
* Lack of moderation or self-control, especially related to sexual desire - see I ...
. This option is not suitable for fistulae that cross the entire
internal
Internal may refer to:
*Internality as a concept in behavioural economics
*Neijia, internal styles of Chinese martial arts
*Neigong or "internal skills", a type of exercise in meditation associated with Daoism
*''Internal (album)'' by Safia, 2016
...
and
external anal sphincter
The external anal sphincter (or sphincter ani externus ) is a flat plane of skeletal muscle fibers, elliptical in shape and intimately adherent to the skin surrounding the margin of the anus.
Anatomy
The external anal sphincter measures about 8 ...
.
* 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
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
''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
Incontinence or Incontinent may refer to:
*Fecal incontinence, the involuntary excretion of bowel contents
*Urinary incontinence, the involuntary excretion of urine
* Lack of moderation or self-control, especially related to sexual desire - see I ...
in a small number of cases, mainly of
flatus
Flatulence, in humans, is the expulsion of gas from the intestines via the anus, commonly referred to as farting. "Flatus" is the medical word for gas generated in the stomach or bowels. A proportion of intestinal gas may be swallowed environm ...
. 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. This was the traditional modality used by physicians in
Ancient Egypt and formally codified by
Hippocrates
Hippocrates of Kos (; grc-gre, Ἱπποκράτης ὁ Κῷος, Hippokrátēs ho Kôios; ), also known as Hippocrates II, was a Greek physician of the classical period who is considered one of the most outstanding figures in the history of ...
, who used horsehair and linen.
*
Seton stitch
A seton or seton stitch is a procedure used to aid the healing of fistulae (abnormal connections between two epithelium-lined organs or vessels).
Techniques
The procedure involves running a surgical-grade cord through the fistula tract so that t ...
– 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 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 in a ''seton''; a cord passed th ...
– 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 fistulae 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.
![Yamai no Soshi - Man with Anal Fistula](https://upload.wikimedia.org/wikipedia/commons/5/50/Yamai_no_Soshi_-_Man_with_Anal_Fistula.jpeg)
*
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.
* Fistula clip closure (OTSC Proctology) is a recent surgical development, which involves the closure of the internal fistula opening with a superelastic clip made of nitinol (OTSC). During surgery, the fistula tract is debrided with a special fistula brush and the clip is transanally applied with the aid of a preloaded clip applicator. The surgical principle of this technique relies on the dynamic compression and permanent closure of the internal fistula opening by the superelastic clip. Consequently, the fistula tract dries out and heals instead of being kept open by continuous feeding with stool and fecal organisms. This minimally-invasive sphincter-preserving technique has been developed and clinically implemented by the German surgeon Ruediger Prosst. First clinical data of the clip closure technique demonstrate a success rate of 90% for previously untreated fistulae and a success rate of 70% for recurrent fistulae.
* VAAFT is a surgical kit for treating anal fistulae. The system comprises:
*# A video telescope (fistuloscope) to allow surgeons to see inside the fistula tract.
*# A unipolar electrode for diathermy of the internal tract. This is connected to a high frequency generator.
*# A fistula brush and forceps for cleaning the tract and clearing any granulation tissue.
The VAAFT procedure is done in 2 phases, diagnostic and operative. Before the procedure, the patient is given a spinal or general anaesthetic and is placed in the lithotomy position (legs in stirrups with the perineum at the edge of the table). In the diagnostic phase, the fistuloscope is inserted into the fistula to locate the internal opening in the anus and to identify any secondary tracts or abscess cavities. The anal canal is held open using a speculum and irrigation solution is used to give a clear view of the fistula tract. Light from the fistuloscope can be seen from inside the anal canal at the location of the internal opening of the fistula, which helps to locate the internal opening. In the operative phase of the procedure, the fistula tract is cleaned and the internal opening of the fistula is sealed. To do this, the surgeon uses the unipolar electrode, under video guidance, to cauterise material in the fistula tract. Necrotic material is removed at the same time using the fistula brush and forceps, as well as by continuous irrigation. The surgeon then closes the internal opening from inside the anal canal using stitches and staples.
Infection
Some people will have an active
infection
An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...
when they present with a fistula, and this requires clearing up before definitive treatment can be decided.
Antibiotics
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention o ...
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.
Epidemiology
A literature review published in 2018 showed an incidence as high as 21 people per 100,000. "Anal fistulas are 2–6 times more prevalent in males than females, with the condition occurring most frequently in patients in their 30s and 40s."
References
External links
{{Authority control
Colorectal surgery
Fistula
A fistula (plural: fistulas or fistulae ; from Latin ''fistula'', "tube, pipe") in anatomy is an abnormal connection between two hollow spaces (technically, two epithelialized surfaces), such as blood vessels, intestines, or other hollow or ...
Diseases of intestines
Fistulas