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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1520_Библиотеки_им_академика_М_И_Перельмана
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47
S.R. Brown et al. (eds.), Contemporary Coloproctology,
DOI 10.1007/978-0-85729-889-8_4, © Springer-Verlag London Limited 2012
4.1 Introduction
It is surprising that none of the quotes about the early use of the term fi stula come
from John of Arderne (1307–1392), whose classic work on the treatment of anal
fi stula is still in print, and who predates them all. It is possible that more has been
written by surgeons about anorectal abscess and fi stula than any other condition
over the expanse of time and world geography [ 1– 4 ] . Hippocrates (b. ~460 BC) of
course described the seton suture and Sushruta (b. ~800 BC) described both fi stulo-
tomy and fi stulectomy as well as the use of cauterizing chemicals in the fi stula track.
These treatments are still in common use (see below). This ongoing concern is a
testament both to the prevalent nature of these disorders and the diffi culty they pres-
ent to the surgeon in basic decision making. The reasons for these diffi cult decisions
are obvious. On the one hand, it is necessary to resolve sepsis and symptoms associ-
ated with it, principally pain, and yet the procedures that one employs must also
preserve function in the anal canal, that is, prevent incontinence. Although surgeons
have been treating anal fi stulas for centuries, evidence supporting the effectiveness
of these treatments is poor and scientifi c study scant (Box 4.1 ) .
R. Nelson , FRCS
Department of Surgery ,
Northern General Hospital ,
Herries Rd. , Sheffi eld ,
S5 7AU , UK
e-mail: richard.nelson@sth.nhs.uk
Chapter 4
Anorectal Fistula
Rick Nelson
48
R. Nelson
Case Scenario 1
A 45-year-old female teacher presents to the emergency take with an acutely
tender perianal lump. She is normally fi t and well, but gets occasional bouts
of loose motions when working. She has a past history of a previous perianal
abscess which she thinks was near the current swelling. On examination, she
appears well. She has a low-grade fever, and the perianal and ischiorectal skin
on the right posterior side of her anus is red, tender, and indurated. There is a
scar within this area where she had her previous abscess drained.
(a) How would you expand the history?
(b) What would be your initial management?
(c) What is the role of antibiotics?
(d) What other surgical options would you consider?
Case Scenario 2
A 26-year-old with Crohn’s disease of the terminal ileum is admitted with
pain, erythema, and copious drainage from two points on the left side of
her perineum anteriorly. Her ileal Crohn’s disease has been controlled with
oral budesonide, which she has been taking for 3 months. She has never
been pregnant and has not undergone any surgical treatment for her Crohn’s
disease.
(a) How would you assess her perianal disease?
(b) What are the therapeutic options to alleviate her anal symptoms?
(c) What is the role of ileal resection?
Box 4.1: Ancient References to Fistula (Oxford English Dictionary,
CR-ROM, Oxford 1995)
1398 Trevisa Barth. de P.R. vii. lix. (1495) 274 Fistula, the fester is a postume
that..rootyth wythin.
1563 T. Gale Antidot. ii. 25 This vnguent..doeth also profyte muche in
Fistulays.
c1570 Sir H. Gilbert Q. Eliz. Acad. (1869) 5 Towching all kindes of Vlcers,
Sores, Phistiloes, wowndes, &c.
1579 Langham Gard. Health (1633) 12 It is good for all wounds, fi stilaes, and
sores of the mouth.
1671 Salmon Syn. Med. iii. xxii. 423 It cools Feavers and cures Ulcers,
Fistulas, Cancers.
1732 Arbuthnot Rules of Diet 360 It happens sometimes to end in a Fistula.
1879 Green Read. Eng. Hist. xviii. 89 Henry, notwithstanding his fi stula and
his fever, was able to sit on horseback.
49
4 Anorectal Fistula
4.2 Demographics
Publications regarding anorectal abscess arise almost exclusively from single institu-
tion experience, which in some cases is very large [ 5, 6 ] . However, these provide no
population-based data. There is no denominator, so incidence cannot be calculated.
Additionally, so many abscesses either rupture spontaneously or may not recur, thus
never work their way to national statistics. However, patients with a fi stula, at least in
adulthood, are very unlikely to have spontaneous resolution. The vast majority of cases
come to a surgeon’s attention. A trip to the operating theater is almost certainly recorded.
In the city of Helsinki, the incidence of fi stula between 1969 and 1978, as determined
by the number of people being treated for it, was 8.6 per 100,000 per year [ 7 ] .
Extrapolation of this fi gure would give an annual incidence in the UK of just over 5,000
cases per year. Other aspects of fi stula demographics include a gender ratio of roughly
2:1 men to women both in Helsinki and North American data [ 8, 9 ] , which is similar to
rates in other large series [ 5, 6 ] . This gender ratio is not maintained when one looks at
other common conditions of the anal canal, such as hemorrhoids and anal fi ssure.
It is also possible to estimate the incidence of perianal abscess from the fi stula
data. Several series have been published in which the rate at which a fi stula was
found at the time of abscess drainage or the percent of patients who had abscesses
drained and were followed prospectively for subsequent fi stula development (or
persistence) were presented [ 6, 10, 11 ] . In these studies, the incidence of fi stula has
varied from 26% to 37%. Working backward, this would translate to an annual esti-
mated incidence of anal abscess of between 14,000 and 20,000 people in the UK.
Though there are anecdotal observations concerning racial and socioeconomic prev-
alence of this condition, no reliable data exist that would allow calculation of a rela-
tive risk for various races or economic classes.
4.3 Etiology
Fistula in the vast majority of cases arises from preexisting abscess. Other etiologies
of anal fi stulas include superfi cial fi stulas associated with anal fi ssure, low rectal
cancer, and anorectal trauma. Fistula is described in patients with ulcerative colitis
Case Scenario 3
A 35-year-old woman comes with a history of a perianal abscess 4 months
earlier and now with persistent purulent drainage from her perineum. She is
otherwise healthy and has had two babies by vaginal delivery. On examina-
tion, she has an external fi stula opening to the left and anterior to her anus,
about 3 cm from the anal verge.
(a) How would you assess her fi stula?
(b) What are the goals of treatment?
(c) What are the options for treating this fi stula?
50
R. Nelson
and Crohn’s disease [ 12 ] , though most surgeons now consider the presence of a
fi stula would indicate that a patient with infl ammatory bowel disease has Crohn’s
disease. A common cause of fi stula described by Goligher that is now apparently
vanishingly rare is tuberculosis of the anal canal [
12 ] .
The etiology of anorectal abscess is perhaps a bit more controversial. The anat-
omy of most fi stulas, with an internal opening at the anal gland in the crypt of
Morgagni would suggest that these abscesses originate with infections of the gland
[
6 ] . British writers felt that such an infection should result in a collection of pus in
the intersphincteric space, between the internal and external sphincter. It is this
belief that lead formerly to a wide internal sphincterectomy being an integral part in
the treatment of abscess and fi stula in Great Britain, thinking that drainage of this
space was necessary to resolve the sepsis. Goligher, in a series in which he routinely
performed sphincterectomy to explore the intersphincteric space, found very few
patients with a collection of pus in this region. He felt these were convincing data
against the cryptoglandular origin or anorectal abscess [ 12 ] . Of these two argu-
ments, the one that has won the hearts and minds of most colon and rectal surgeons
is the one related to fi stula anatomy and cryptoglandular origin.
4.4 Risk Factors/Prevention
Despite the extensive description of this topic, no feature of body habitus, bowel
habit, diet, or toxic exposure has ever been described that increases the risk for the
fi stula, or the alteration of which might decrease risk for fi stula developing. In fact,
the analytic epidemiology of the sort that is seen with great frequency for cancer of
the colon or breast or coronary artery disease has never been performed for anorec-
tal abscess or fi stula. Why this disease should occur more frequently in men and
why it should occur most commonly between the ages of 20 and 45 are unknown.
4.5 Morbidity of Abscess and Fistula
Almost all patients with abscess present with anorectal pain. Systemic sepsis may
accompany this pain. Very rarely, patients may present with no localizing symptoms
and signs of sepsis, and the source is subsequently found arising from the anal
canal. Patients with fi stula may present with either pain or sepsis, but far more com-
monly they have drainage either of pus or blood from the perianal region, unrelated
to defecation. Sepsis may in some cases of perianal abscess be overwhelming and
life-threatening. When such is the case, especially in a diabetic (or immunosup-
pressed patient) with gangrenous skin changes, this constitutes a surgical emer-
gency. Repeated debridement in lieu of a colostomy is the accepted treatment. For
patients with anal fi stula, the risk of recurrent sepsis is always present.
51
4 Anorectal Fistula
In patients with chronic anorectal disease, the risk of developing cancer has been
noted [ 13 ] . One study found six cancers in preexisting fi stulas. The fi stulas had been
present for a mean of 13.8 years. In none of these six was there an intraluminal
rectal tumor. In three of the six, the cancer was unsuspected at the time of surgery
and only revealed to the surgeon when the pathologist phoned up 3 days later [
13 ] .
Several case control and cohort studies have been published which allow a numeri-
cal calculation of anal cancer risk related to fi stula. These have in each case shown
a statistically signifi cant association of untreated fi stula with subsequent cancer
development [
14 ] . In those cohort studies in which the carcinoma diagnosis quickly
followed treatment for anal fi stula, one might suppose that the cancer arose simul-
taneously with the fi stula or may have even caused it. However, anal cancer tends to
be an aggressive tumor [ 13, 15 ] . For those individuals in whom the tumor diagnosis
was made years after the fi stula diagnosis, it would seem more likely that the cancer
arose in a preexisting fi stula. The pathophysiology of this malignant change has
been studied extensively in other organs in which chronic infl ammation often pre-
dates the diagnosis of cancer (such as in ulcerative colitis [ 16 ] ). For a benign condi-
tion such as fi stula, eradication of the infl ammatory focus can be accomplished with
minor surgery and low morbidity. This is a strong argument in favor of expeditious
surgical treatment of patients with anorectal abscess and fi stula.
4.6 Diagnosis
The principal symptom of abscess is pain. The diagnosis of an anal abscess is there-
fore established by considering fi rst the differential diagnosis of anal pain. This
includes, with abscess and fi stula, anal fi ssure, hemorrhoidal thrombosis, proctitis,
levator spasm, venereal diseases, and cancer. Because of the great distress that anal
pain causes patients and the morbidity involved in delayed diagnosis of abscess, it
is important expeditiously to determine the source of the pain. In many patients with
abscess, examination will reveal the classic triad of rubor, tumour, and callor, that
is, a hot red tender area adjacent to the anus. However, many abscesses arise deep
within pelvic tissue planes and may not be clinically apparent on external examina-
tion. Additionally, the patient with anal pain is resistant to digital examination of the
anal canal, much less endoscopy, as they have tenderness as well as pain. Though
there are many techniques which may infer the presence of an abscess, such as com-
puterized tomography, magnetic resonance imaging, or radionucleotide white cell
scanning, none of these are comparable in accuracy or therapeutic potential to an
expeditious trip to the operating theater for examination of the anal canal under
anesthesia by an experienced surgeon. In the UK, this is usually performed under
general anesthetic. However, in the USA, it is usually done under regional anes-
thetic, allowing the patient to control their own airway, and in the prone jackknife
position. There is no evidence that the performance of a spinal anesthetic in a patient
with anorectal sepsis increases the risk of meningitis.
52
R. Nelson
If an abscess is suspected and especially if the patient is very septic, there is no
reason to delay surgical exploration in order to explore alternative diagnostic tech-
niques, or to attempt further resuscitation for resolution of the sepsis. For a diabetic
with a gangrenous infection, early exploration, drainage, and debridement is the
fi rst step in controlling both their sepsis and diabetes. A special case where right
answers seem elusive is a patient with acute leukemia and pancytopenia, perhaps
either being prepared for or having just received a bone marrow transplant. Induration
in the perineum is not always present, and there is an understandable desire not to
perform surgery in these very sick patients. Perianal sepsis is life-threatening in
these patients, and urgent incision and drainage is essential.
Sometimes the anatomy of a fi stula seems impossible to delineate at surgery.
Insertion of a small catheter, such as those used for cholangiography, into the fi stula
with peroxide injection during surgery can aid in the identifi cation of an internal
fi stula opening. Fistulography has been described but provides limited information
and has been superseded by other imaging modalities [
17 ] . Radiolabeled white cell
scanning has also been used in fi stula patients, though its greatest usefulness is
probably in ruling out proximal infl ammatory bowel disease [ 18 ] .
The current most useful imaging techniques for assessing an anal fi stula are ano-
rectal ultrasound (ARUS) and magnetic resonance imaging (MRI). Studies have
assessed the effi cacy of these imaging techniques not just in anatomic defi nition but
also in directing patients to improved outcomes when compared to preoperative and
even intraoperative physical examination of the anal canal [ 19– 21 ] . MRI has been
established as the reference standard in this regard, though one study suggested that
ARUS came a close second. Whether a patient with a simple fi stula going to surgery
for the fi rst time needs a preoperative MRI might be debated, but it is certainly
needed for recurrent or complex disease.
4.7 Treatment of Anal Abscess
The remainder of this chapter will be limited to evidence obtained from randomized
controlled clinical trials (RCTs) and systematic reviews of RCTs. Regarding abscess,
there are a total of six RCTs that assess the feasibility of incision, curettage, and
primary closure of perirectal abscess. Two of these trials involve abscess in all loca-
tions of the body, in which anorectal disease formed an important subset, but the
results published did not separate those patients from the whole group [ 22, 23 ] . Two
more studies applied curettage and closure to all patients and simply studied various
antibiotic combinations [ 24– 26 ] . Two other studies are of greatest interest because
they randomized patients to traditional incision and drainage or primary closure.
The fi rst of these was published over a generation ago when antibiotic choices were
primitive [ 27 ] . In fact, antibiotic therapy varied during the study as new drugs
became available. It was a large study with over 100 patients in each arm: patients
with existing fi stula were excluded. A major problem with this study was incom-
pleteness of follow-up. Barely, a third of their patients were seen up to a year after
surgery. In this staggered follow-up, 26 patients with incision and drainage had
53
4 Anorectal Fistula
recurrence and or fi stula persistence whereas only eight of the patients with suture
had recurrence. A similar study performed several years later randomized 41 patients
to incision and 42 to closure with clindamycin cover. Fistulotomy was done as part
of the procedure if a fi stula was found at exploration. Though early results of this
trial suggested that recurrence or persistence of fi stula was more common with con-
ventional incision and drainage [
28 ] , a second publication presenting 3-year follow-
up turned the tables, showing almost twice as many patients recurred with prolonged
follow-up after primary closure of the abscess [ 29 ] .
4.8 Treatment of Anal Fistula
The operations still in common clinical use are listed in Box 4.2 . Fistulotomy is
the gold standard for eradication of fi stulas in ano. Alternative procedures have
been developed, not to improve cure rates, but to preserve continence. However,
cure of fi stula in ano even by fi stulotomy is not always certain. Recurrence var-
ies from 2.3% to 13% in selected series (median 11%) and, when only trans-
sphincteric fi stulas are considered, recurrence rates after fi stulotomy are reported
to increase to 13–37% [ 30– 37 ] . Looking at alternatives to traditional fi stulo-
tomy, the operation about which most is written is rectal fl ap closure of the inter-
nal fi stula opening. The price that is paid for preservation of sphincter integrity
with a fl ap is that the reported fi stula recurrence rate for rectal fl aps is greater
than 25% [ 38– 40 ] .
Box 4.2: Operations for Anal Fistula
Fistulotomy The gold standard, but still only 85% successful
Fistulectomy We are taught never to do it, but one randomized study
shows no difference in incontinence risk when
compared to fi stulotomy.
Seton Cutting or temporary or permanent or with cauterizing
chemicals or internal sphincter preserving. No two
surgeons seem to use a seton in exactly the same
manner. (Who was Seton?)
Fibrin glue A matrix for fi broblast migration and healing of the
fi stula track
Fistula plug Collagen skeleton from skin or intestine and from various
species. Also a matrix also for fi broblast migration
Flap closure Mucosal or full thickness anorectum or dermal. All aim
to close the internal opening only
Autologous stem
cells
In a fi brin glue mix and with one RCT supporting
effi cacy. Overcomes fi broblast shyness compared to
collagen or glue?
54
R. Nelson
There are two published Cochrane reviews concerning anal fi stula. The fi rst
focuses only on whether fi stulotomy should be done at the same time that a
perianal abscess is incised and drained [ 41 ] . This is a simple question and there
are six published RCTs. However, the question is not clearly answered in this
systematic review due to quality issues in these trials. Most notably, from case
series, it is known that fi stulas develop only in about 30% of patients in whom
abscesses are drained. Yet, in those randomized before going to surgery to inci-
sion, drainage, and immediate fi stulotomy, fi stulas were found and laid open in
88–100% of the patients. Most of these patients would not have developed fi s-
tulas. Incontinence was seen more often in those having fi stulotomy, but there
was not a signifi cant difference between the two groups in part due to heteroge-
neity in the analysis. The review concluded that fi stula surgery at the time of
incision and drainage of a perianal abscess signifi cantly reduces the likelihood
of persistent fi stula or abscess and the need for repeat surgery. A small number
of patients may get transient incontinence following abscess drainage with fi s-
tula treatment (see Table 4.1 ). The evidence that patients may get minor incon-
tinence for longer following fi stula surgery with abscess drainage remains weak.
Sensitivity analyses excluding studies with signifi cant quality issues or proce-
dural variations all gave very similar relative risks with widening of the confi -
dence intervals as patient numbers decreased in the analyses. These conclusions
should not be applied to patients with high or suprasphincteric anal fi stulas or
other groups (anterior fi stulas in female, previous anorectal surgery or trauma,
infl ammatory bowel disease, and HIV) who are at high risk for continence
issues.
The second review looked more broadly at surgical options for anal fi stula, but
in an effort to answer the less complicated question fi rst, studies of complex,
suprasphincteric, or Crohn’s fi stulas were excluded. Ultimately only ten RCTs
were included in the review, some addressing some fairly peripheral questions,
such as using radio-frequency probes rather than diathermy for fi stulotomy
(Table 4.1 ). These authors conclude in their review “The ideal treatment for fi stula
in ano has not yet been elucidated. There is surprisingly little good evidence, as
LIFT Ligation of the intersphincteric fi stula track. New with
an enthusiastic following. No completed RCTs yet.
See
ClinicalTrials.gov. also http://www.youtube.
com/watch?v = zHSYutaulK4
Marsupialization Fistulotomy with track narrowing to speed wound
healing. Why should it improve continence?
What is missing?
Fistula closure That is, simple or layered closure of the internal
opening only. Intuitive but never studied? No RCTs
55
4 Anorectal Fistula
Table 4.1 Treatments of anal fi stula assessed in Cochrane reviews [ 41 ]
Intervention Comparator
No. of
studies N = Recurrence risk Incontinence risk Comments
I&D + fi stulotomy I&D only 6 474 0.13 (0.07–0.24) 3.06 (0.7–13.45)
Very poor quality studies
Fistulotomy Fistulectomy 1 45 1.36 (0.2–9.02) 0.26 (0.02–2.72) Why has this only been tested
once?
Fistulotomy +
marsupialization
Fistulotomy alone 2 137 1.26 (0.27–5.97) 2.29 (0.66–7.97) Faster healing. Does faster
healing equate to less
incontinence?
IAS preserving seton Conventional
seton
1 34 1.88 (0.15–22.88) 0.412 (0.03–5.03) NS
Ayurvedic seton Fistulotomy 1 100 0.38 (0.02–9.64) 2.07 (0.47–9.19) NS
Fibrin glue Fistulotomy or
seton
1 13 15 (0.6–376) NA NS
Radio-freq. cut Conventional
surgery
2 122 0.73 (0.15–3.48) 0.44 (0.14–1.41) NS
Fibrin glue + fl ap Flap alone 1 58 0.29 (0.09–0.92) NA No incontinence in either group
Island fl ap anoplasty Fistulotomy/seton 1 20 NA NA No recurrence or incontinence
56
R. Nelson
Table 4.2 Randomized trials not included in Cochrane reviews
First author Year Intervention Comparator N =
Outcome
Shukla [
43 ] 1991 Ayurvedic seton Fistulectomy or
fi stulotomy
502
40% lost to follow-up
Belmonte-Montes [
44 ] 1999 Fistulotomy Fistulectomy 40 No outcome data
Zimmerman [
45 ] 2003 Scott (aka LoneStar)
retractor
Parks retractor 30 Scott preferred for resting pressure ( p = 0.035) and
continence preservation ( p = 0.038)
Singer [
46 ] 2005 Fibrin glue + antibiotic,
internal opening
closure or both
75 Healing in 25–44%
Chen [
47 ] 2005 Intrasphincteric Fistulectomy 92 Recurrence equal. Incontinence better with
intra-sphincteric approach ( p < 0.01)
Perez [
48 ] 2006 Fistulotomy and
immediate sphincter repair
Mucosal fl ap 60 2/30 in each group recurred
Gustafsson [
49 ] 2006 Flap + gentamicin
collagen
Flap alone 83 p = 0.45
Garcia-Olmo [
50 ] 2009 Fibrin glue + autologous stem
cells
Fibrin glue alone 49 Crohn’s included. 17/24 healed with glue + cells.
4/25 with glue alone. OR = 4.43; CI = 1.7–11.3
Hammond [
51 ] 2010 Fibrin glue + cross-linked
collagen
Glue alone 29 12/15 glue + collagen healed. 7/13 glue alone healed
(NS).
Grimaud [
52 ] 2010 Fibrin glue Observation 71 All Crohn’s. 13/34 in “remission” in glue group.
6/37 in observation group
Khafagy [
53 ] 2010 Full thickness fl ap
repair
Mucosal fl ap 40 18/20 healed in the full thickness group. 12/20 in
the mucosal fl ap group. Incontinence to fl atus in
2/20 in the full thickness group only
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