Objective: Fistula-in-ano is a common condition that is characterized
by intermittent pain and discharge. We present an audit of all patients seen
with anal fistula at Prince
Hashem Hospital
during an eighteen month period.
Methods: This audit includes all patients that underwent
examination under anesthetic for fistula-in-ano from September 2006 to May
2008. Anatomic classification and operative procedures of all fistulae were
recorded. Patients were followed-up for a mean period of 13 months and details
of wound healing, fistula recurrence and function were gathered.
Results: Forty three consecutive patients underwent
examination under anesthesia for fistula. There were 36 males with a mean age
of 32.2 years (range 17-65). Eight (18.6%) patients had superficial, 15 (34.9%)
intersphincteric, 17 (39.5%) transphincteric, 3 (7%) suprasphincteric and none
had extrasphincteric fistulae. Forty (93%) patients had fistulae of
cryptoglandular (idiopathic) origin. Two (4.7%) patients had Crohn’s disease
and one (2.3%) had low rectal malignancy. Thirty two (74.4%) patients underwent
fistulotomy. One (2.3%) patient had advancement flap. Nine (21%) patients had
loose seton in situ and one patient underwent abdominoperineal resection. Four
(9.5%) patients had some degree of flatus incontinence, two (4.8%) had
incontinence to liquid stool. Soiling was present in one patient.
Conclusions: Fistula-in-ano is relatively a common condition in Jordan.
Its variation in anatomical distribution should alert the surgeons for the
variety of surgical options available for its treatment, especially the
difficult and complex ones, that should be managed by a colorectal surgeon or
general surgeon that has adequate experience in this field. Unusual causes like
Crohn’s disease and malignancy should be kept in mind in complex, unhealed
fistulae.
Key words: Fistula-In-Ano, Fistulotomy, Incontinence.
JRMS
March 2010; 17(1): 43-49
Introduction
Fistula-in-ano is
relatively a common condition defined by an abnormal track that
connects two epithelialized surfaces, usually the anal canal to the
perianal skin. The cryptoglandular theory of Parks(1) is now
widely accepted. Parks found cystic dilatation of anal glands in eight of 30
consecutive cases of anal fistula. He attributes this to either acquired duct
dilatation or a congenital abnormality and suggested that it was a precursor to
infection within a mucin-filled cavity.
In addition to fistulas of cryptoglandular origin,
other causes like trauma, Crohn's disease,(2) malignancy,
radiation, or unusual infections (tuberculosis, actinomycosis, and chlamydia)
may also produce fistulas. A complex, recurrent, or nonhealing fistula should
raise the suspicion of one of these diagnoses.(3)
Sir Alan Parks
provided a detailed classification of anal fistula that withstood the test of
time.(4) He
classified fistula into intersphincteric, transphincteric, suprasphincteric and
extra-sphincteric. A prospective study(5) from St Mark’s
hospital in 2000, demonstrated that 86 (88%) out of ninety eight patients had
fistulae of cryptoglandular (idiopathic) origin. Fistulae were superficial in
11 (11%) patients, intersphincteric in 30 (31%) patients, transphincteric in 52
(53%) patients, suprasphincteric in three (3%) patients and extra-sphincteric
in two (2%) patients. Forty nine (50%) fistulae were classified as
complex.
Proper management of
fistula-in-ano is an important aspect of colorectal practice. The principles of
fistula surgery are to eliminate the fistula, prevent recurrence and preserve
sphincter function. Success is usually determined by identification of the
primary opening and dividing the least amount of muscle possible.
The majority of anal fistulae are simple and low and
can be identified properly by digital examination and satisfactorily treated by
fistulotomy.(6,7)
More complex fistulae, in which there may be
involvement of a substantial portion of the sphincter muscles and/or there is
multiple secondary tracks need further investigations either by endoanal
ultrasonography or magnetic resonance imaging.(8,9) These
fistulae pose a surgical challenge, as fistulotomy in such cases may render the
patient incontinent.(10) Common techniques for dealing with
difficult fistulae include the use of either cutting or loose setons(11,12)
and advancement flaps.(13,14) More recently the use of
a fibrin sealant has been described.(15,16,17)
The aim of this study
is to assess prospectively the presentation, classification, management and
outcome of a consecutive series of patients with Fistula-In-Ano.
Methods
From September 2006 to
May 2008 all patients who underwent examination under anesthesia for Fistula-In-Ano
at Prince Hashem Hospital (PHH) in Zarka/Jordan were prospectively followed for
a period of 13 months (range 2-20).
At the first
presentation, patients with anal pathology were assessed in the clinic.
Patients with Fistula-In-Ano were given an appointment for examination under anesthesia.
Those who had other anal pathologies were treated accordingly either
conservatively or surgically. Anovaginal and rectovaginal fistulae were
excluded. Records were kept of details of existing and previous anal pathology,
investigations, medical and surgical treatments.
All patients were questioned
regarding their continence prior to surgery. The surgery was performed by the
first author. All patients underwent examination under anesthesia in the
lithotomy position with cleaning of the anal region and draping, and
comprehensive operative details were recorded. Fistulae were classified on the
basis of operative findings and according to Parks' classification.(4)
The internal opening of the fistula
tract was identified manually, where this failed, H2O2
was used. Treatment was initiated according to the site of the fistula, its
primary and secondary tracks and state of the sphincters. At follow-up, details
of wound healing, flatus and faecal continence, fistula recurrence and further
surgical interventions required were recorded.
Results
Forty three patients
were audited. There were 36 (84%) males and seven (16%) females, with a mean
age of 32.2 years (range 17-65). Mean duration of symptoms prior to
presentation was 18 months (range 2-40). Twelve (28%) patients had previous
surgery for fistula. They underwent a total of 18 surgical procedures (range
1-3) at PHH and other hospitals. Operations ranged between fistulotomy, tight
seton and fistulectomy with or without primary closure. Five patients had other
different surgical procedures, including internal lateral sphincterotomy (n=2)
and haemorrhoidectomy (n=3). None of the female patients had major obstetric
trauma, but five had episiotomies during delivery. Thirty seven (86%) patients
had an abscess preceding their fistula. Thirty of them were drained surgically
and seven were spontaneously drained.
The aetiology of
fistula was idiopathic in 40 (93%) patients, Crohn’s disease in two (4.7%) and one
(2.3%) patient had low rectal malignancy with fistulization into the perineum.
Eight patients underwent magnetic resonance imaging (STIR sequence) for the
fistula.
Under general
anesthesia with prophylactic antibiotics, all patients had examination in
lithotomy position. The operative findings were as follows: eight (18.6%)
fistulae were superficial, 15 (34.9%) intersphincteric, 17 (39.5%)
transphincteric, three (7%) suprasphincteric (see Table I).
Table I. Fistula history, aetiology and operative findings
|
|
Male
|
Female
|
|
Patients
|
36
|
7
|
|
Preceding abscess
|
33
|
4
|
|
Previous surgery for
fistula
|
10
|
2
|
|
Episiotomy
|
-
|
5
|
|
Previous anal surgery:
|
|
Lateral sphincterotomy
|
2
|
-
|
|
Haemorrhoidectomy
|
1
|
2
|
|
Aetiology:
|
|
Idiopathic
|
33
|
7
|
|
Crohn’s
|
2
|
-
|
|
Rectal Cancer
|
-
|
1
|
|
Operative findings:
|
|
Superficial
|
7
|
1
|
|
Intersphincteric
|
13
|
2
|
|
Transphincteric:
|
|
|
|
Low
|
5
|
-
|
|
Mid
|
5
|
1
|
|
High
|
5
|
1
|
|
Suprasphincteric
|
2
|
1
|
Table II.
Operations performed
|
|
Fistulotomy
|
Loose seton
|
Advancement Flap
|
AP excision
|
|
Superficial
|
8
|
|
|
|
|
Intersphincteric
|
15
|
|
|
|
|
Transphincteric
|
|
|
|
|
|
Low
|
5
|
|
|
|
|
Mid
|
4
|
2
|
|
|
|
High
|
|
5
|
|
1
|
|
Suprasphincteric
|
|
2
|
1
|
|
Ten (23%) patients had
complex fistulae. This included horseshoeing (n=4), more than one opening (n=6)
and secondary extensions (n=7).
The external and
internal openings were identified. The internal opening was in the posterior
anal canal in 25 (58%) of cases, in the lateral canal in seven (16%) and in the
anterior canal in 11 (26%). The external opening was in different positions
around the anus.
Surgical treatment for
each primary fistula track is shown in Table II. The commonest procedure
performed was fistulotomy (n=32), 16 of which were also marsupialized.
All superficial and intersphincteric fistulae
were layed open. Five out of 17 of transphincteric fistulae were of the low
type and were also managed by laying them open. Regarding the mid
transphincteric type, the approach was different and tailored to each patient
individually depending on bowel habits, state of the sphincter on digital
examination and the bulk of muscle above the internal opening. All four
patients who had fistulotomy were males. Permanent loose seton was applied for
both females with mid transphincteric fistula. Also loose seton was applied for
high and suprasphincteric fistulae. Two patients with Crohn’s disease had loose
seton for high transphincteric fistulae.
One of them had previous fistulotomy
for superficial fistula. One male patient with suprasphincteric fistula had
endorectal advancement flap. One female patient that presented with perianal
abscess and fistula-in-ano had also rectal bleeding. Digital rectal examination
in the clinic showed a low rectal mass. Under general anaesthesia she had
drainage of the abscess, biopsy of the mass and for control of the fistula a
loose seton was inserted. She had a definitive surgery (abdominoperineal
excision) later on for low rectal malignancy. Of the seven patients with loose
setons (excluding two with Crohn’s disease) three agreed to have endorectal
advancement flap, they are on the waiting list. Horseshoe fistula track was
noted in four patients and secondary extensions were seen in seven cases. In four out of seven cases the primary fistula track
Table III.
Fistula surgery complications
|
Fistula type
|
Operation
|
Incontinence
|
Management
|
|
Superficial
|
Fistulotomy
|
Flatus incontinence
|
None
|
|
Intersphincteric
|
Fistulotomy
|
Soiling
|
Pads
|
|
|
Fistulotomy
|
Flatus incontinence
|
None
|
|
Transphincteric
|
Fistulotomy
|
Liquid stool
|
Loperamide
|
|
|
Fistulotomy
|
Liquid stool
|
Loperamide
|
|
|
Loose seton
|
Flatus incontinence
|
None
|
|
|
Loose seton
|
Flatus incontinence
|
None
|
Table IV. Comparison of series
|
|
Vasilevsky &
Gordon 1984
(n . 160)15
|
Malouf et al
2000
(n . 98)4
|
Current audit
(n=43)
|
|
Superficial
|
N/S
|
11%
|
18.6%
|
|
Intersphincteric
|
41.9%
|
31%
|
34.9%
|
|
Transphincteric
|
52.1%
|
53%
|
39.5%
|
|
Suprasphincteric
|
1.3%
|
3%
|
3%
|
|
Extrasphincteric
|
0%
|
2%
|
0%
|
was layed open, with
curettage of the secondary tracks. Three patients had loose seton for the
primary track with secondary tracks laid open.
Wound bridging requires further surgery in two patients. Fistula
recurrence due to missed secondary tracks was seen in another two patients;
they were low transphincteric and were treated by fistulotomy.
During the follow-up
period, two patient developed some degree of faecal incontinence; they were
patients with mid transphincteric fistula who had fistula surgery earlier. They had incontinence to liquid stool and were
managed by antidiarrheal medications. One
patient who had fistulotomy for superficial fistula developed mild incontinence
to flatus; she was a patient with previous anal surgery (haemorrhoidectomy). Regarding
patients that underwent lay open of intersphincteric fistulae, one developed
soiling and the other had flatus incontinence. Patients that
developed incontinence to flatus were patients with complex fistulae that had
loose seton for the primary tract, and the secondary extensions were laid open (see
Table III).
Wound healing was
satisfactory in majority (40) of patients. An average time was six weeks (range
1-20). We had two recurrences in this study
group; they were patients whose secondary tracks were missed during
fistulotomy.
Discussion
A proper management of
fistula-in-ano is an important aspect of colorectal practice. A better
understanding of the anatomy of the fistula and anal sphincters allowed a more
definitive treatment of complex fistulae. The anatomic distribution of fistulae
in the study patients is comparable to other studies(5,18) (see
Table IV) where the majority is transphincteric fistulae followed by
intersphincteric, and the least common is extrasphincteric fistulae.
The prevalence of
fistula formation after drainage of an anorectal abscess is around 30%.(19)
Persistent discharges from the drainage site and/or recurrent abscess
formation are usual indications that a fistula is present. A high prevalence of
fistula formation after abscess drainage in this study (86%) is probably due
to: first some abscesses are drained in the emergency department under local anesthesia
and, second these abscesses are drained by a junior surgeon. These two reasons
can carry a substantial risk of fistula formation.
A majority of anal
fistulas have a single simple fistula track that is easily identified during
surgery, and surgical treatment is generally successful. However, 5%–15%(20)
of anal fistula tracks have a more complicated course, with secondary
extensions outside the anal sphincter, often with horseshoe fistulas and
ischiorectal and supralevator abscesses. These so-called complex fistulas are
often associated with recurrent fistulas and fistulas associated with
underlying Crohn’s disease. Failure in accurate assessment of the secondary
extensions during surgery may be responsible for the high rate of recurrence.(20,17)
We used magnetic resonance imaging, Short Taw
Inversion Recovery (STIR) sequence, which suppresses signals from fat and
highlights fistula, to identify secondary extensions and horseshoeing of the
fistula in PHH patients. In contrast, endoanal sonography (EUS),(21) sometimes complemented with probing,
is well comparable to bodycoil MRI in classifying and describing the topography
of anal fistula.(8,22) All eight patients in this study who had
MRI, were the patients with previous surgeries for fistula. Scaring from
previous surgery makes it difficult to outline the fistula tract manually.
The EUS examination is simple for the patient
and can be performed by a surgeon with training in EUS.
Although the
superficial type of fistula was not present in Parks classification,(4)
because of the emphasis on the
intersphincteric plane. These are common and make up around 16% of one series.(19)
However; in this study series it is present in 16.2% of the study patients.
The best treatment for
an anal fistula is to lay it open. Obviously if this involves cutting a large
amount of anal sphincter this will cause incontinence. Bennett in 1962 said:
‘It is poor consolation for the fastidious patient who, after 17 weeks off work
for treatment of his horseshoe fistula, finds that his underclothes are stained
brown instead of yellow, even though his fistula is healed’.(23)
This study shows that
most fistulae can be treated satisfactorily by lay-open techniques, even many
mid trans-sphincteric fistulae in which a seemingly substantial part of the
external sphincter is divided. Sir Alan Parks, in his classic paper, stated
that `as a general rule the whole of the internal and most of the external
sphincter can be cut, with the exception of the puborectalis muscle, without
any serious loss of function'.(4) One centimetre of normal
sphincter muscle above the internal opening may be sufficient for the primary
track to be laid open.(24) This is most applicable to males with
no history of previous fistula surgery or perineal surgery but should be
adopted with caution in females whose anterior external sphincter and anal
canal have been demonstrated to be shorter, and often harbor occult obstetric
injury.(5)
Nine patients in this study had permanent loose seton,
it is another definite treatment of complex fistulae. However three out of seven
patients (excluding two patients with Crohn’s) with loose seton are waiting for
the endorectal advancement flap procedure.
One male patient with suprasphincteric
fistula in this audit represented a high risk for fistulotomy and was managed
by endorectal advancement flap. He had no symptoms of faecal incontinence.
Advancement flaps are
usually employed where cure is sought but yet where fistulotomy might
compromise function too much. Mizrahi et al(25) showed
that the success rate of the endorectal advancement flap is modest at a
follow-up of up to 12 years. The only factor predictor of failure is a
diagnosis of Crohn’s disease. However, female gender, a rectovaginal location,
or the prior performance of two or more repairs may also predispose to failure.
Different
management procedures for the horseshoeing of the fistula is dependant on the
level of crossing of the primary tract in the external sphincter muscle (where
there is mid to high cross a loose seton was applied other wise fistulotomy was
performed).
Marsupialization of
anal fistulotomy wounds leaves less raw unepithelialized tissue to granulate
and may improve wound healing. Ho et al.(26) concluded
that marsupialization of fistulotomy wounds resulted in more rapid healing and
less deformed wounds. This is why 50% of the study patients who underwent
fistulotomy had also marsupialization of the wound.
Risk factors for
developing incontinence after fistula surgery are well-documented(27)
and these can usually be identified by clinical assessment.
Manometry is advocated by some to help direct the surgical approach and
therefore prevent incontinence developing after fistula surgery,(28)
however, its routine use is by no means universal practice. Whilst
maintenance of the anorectal ring was previously considered the only necessity
to maintain continence after fistulotomy, high external anal sphincter division
which may occur with transphincteric fistulas may lead to impaired continence,
associated with lower distal anal canal pressure.(29)
Because of the
unavailability of the anal manometer in PHH, we could not predict patients who
may develop incontinence after the surgery. In a prospective study by Lunniss et
al.(30) nineteen of 37 patients undergoing
fistulotomy noted minor degrees of incontinence postoperatively. In contrast only
eight of 43 in this audit had incontinence postoperatively. This may be explained by less complicated
fistulas in this series and more conservative approach in the treatment,
reflecting by using a loose setons for high fistulas.
Fistula may recur due
to failure of technique such as advancement flap, further sepsis caused by skin
bridging, or failure to detect and eradicate all tracks and openings at initial
surgery. The reported incidence of success in this
kind of operations is between 46-100%(31)
with the incidence of incontinence from 0-35%.
Two cases of
recurrence in this audit were in patients who had secondary extensions that
were missed initially. Few reports of long-term follow-up and recurrence exist.
An average follow-up of just over three years of 160 patients reported a
recurrence rate of 6.3%,(15,18) most often seen in those
patients in whom high blind tracks were evident at EUA. A distinction must be
made between true recurrence following treatment and persistence of fistulae
resulting from inaccurate assessment. The overall recurrence in our series was 4.7%.
We used loose setons
in nine patients, usually for more difficult fistulas and patients with Crohn’s
disease. Such an approach allows initial drainage of sepsis prior to subsequent
definitive treatment to eradicate the fistula. Approximately 50% of fistulae
will heal after seton removal without external sphincter division, and this can
be performed when the external opening of the fistula has closed around the
seton approximately three months after insertion.(32)
Conclusion
Fistula-in-ano is
fairly common in Jordan,
its variations in its anatomical distribution led to a wide range of available
treatment options, but fistulotomy is the commonest acceptable method, it gave
excellent results in the majority of cases, but it carries a risk of minor
incontinence. Sphincter saving procedures like advancement flap is an
alternative option, but it is technically demanding, and can cure fistula with
no or minimal disturbance in continence.
The more complex and difficult
the fistula, the more complex surgical option should be applied, and the more
experienced general or colorectal surgeon should perform it.
Fistula in association
with Crohn’s disease should be managed as much conservatively as possible. Other modalities in treatment of fistula like
plugs and glues should be kept in mind.
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