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200 C.-A. Vasilevsky and P.H. Gordon
initial surgery, to determine the relationship of the fistula tract
to the sphincter mechanism, and to reveal the site of sepsis in
a recurrent fistula, all serving to decrease recurrence rates
associated with fistula surgery. Imaging may take the form of
fistulography, computed tomography (CT) scan, endoanal
ultrasound, and magnetic resonance imaging (MRI).
Fistulography
Fistulography, which involves cannulation of the external
opening with a small feeding tube and injection of water-soluble contrast may be useful in the evaluation of recurrent fistulas or in Crohn’s disease where previous surgical forays or
38
disease may have altered anorectal anatomy
(Figure 13-11).
Contrast is introduced at low pressures for fear of tissue disruption. This may not allow secondary tracts to fill with contrast. It is difficult to distinguish between an abscess located
high in the ischioanal fossa and one located in the supralevator space. In addition, the level of the internal opening may be
difficult to see because of the absence of precise landmarks.
Contrast may reflux into the rectum wrongly suggesting an
extrasphincteric tract with a rectal opening thus resulting in
FIGURE 13-10. Goodsall’s rule.
injudicious probing. Accuracy rates in identifying the internal
openings and extensions in one study were found to be 16%,
whereas a subsequent study found fistulography to be useful
was especially true in women in whom fistulas with anterior
external openings tracked in a radial manner in only 31%.
36
Digital rectal examination may reveal an indurated cordlike structure beneath the skin in the direction of the internal
opening with asymmetry between right and left sides. Internal
in 96%.
revealed other surgical pathology in 48%.
reasons outlined previously, to have a false-positive rate of
12%.
the dissemination of sepsis.
38,39
Its use resulted in altered surgical management or
39
Fistulography is invasive and potentially may result in
38
It was found, for
openings may be felt as indurated nodules or pits leading to
an indurated tract.
36
Posterior or lateral induration may be palpable indicating fistulas deep in the postanal space or horseshoe fistulas.
35,36
Bidigital rectal examination will define the
relationship of the tract to the sphincter muscles and provides
information as to preoperative sphincter tone, bulk, and voluntary squeeze pressure which need to be assessed preoperatively because of a possible risk of incontinence.
17,35
Investigations
Anoscopy should be done before operation in an attempt to
identify the primary opening. Sigmoidoscopy should be
performed to locate a proximal internal opening and to
exclude underlying pathology such as proctitis or neoplasia.
Colonoscopy or barium enema and a small bowel series are
indicated in patients who have symptoms suggestive of
inflammatory bowel disease and in patients with multiple or
recurrent fistulas. Although anal manometry is not generally
required, it may be useful as an adjunct to planning the operative approach in women with previous obstetric trauma, in an
elderly patient, a patient with Crohn’s disease or AIDS, or in
a patient with a recurrent fistula.
The role of preoperative imaging is to demonstrate clini-
cally undetected sepsis, to serve as a guide at the time of the
37
FIGURE 13-11. Fistulogram. Arrowheads indicate fistula tract.
13. Benign Anorectal: Abscess and Fistula 201
CT Scan
CT scanning performed with intravenous and rectal contrast is
a noninvasive method used to assess the perirectal spaces. Its
use may be to distinguish an abscess requiring drainage from
perirectal cellulitis. It does not permit visualization of tracts
in relation to the levators.
Endoanal Ultrasound
The role of endoanal ultrasound is to establish the relation of
the primary tract to the anal sphincters, to determine if the fistula is simple or complex with extensions, and to determine the
location of the primary opening. It may aid in the identification
of complex fistulas and may serve as an adjunct in the evaluation of complex suppuration to assess the adequacy of
drainage
40
(Figure 13-12a). A prospective study that compared
this modality to digital examination found that although
endosonography was able to detect a large portion of intersphincteric and transsphincteric tracts, it was unable to detect
primary superficial, extrasphincteric and suprasphincteric tracts
or secondary supralevator or infralevator tracts.
ducted 10 years later
42
using a 10-mHz probe along with injec-
41
A study con-
tion of hydrogen peroxide into the tract, was able to identify the
internal opening in 93%. Although this investigative modality
is rapid and well tolerated, it is operator dependent and scars or
defects caused by previous sepsis, surgery, or trauma will confuse ultrasonographic interpretation and make delineation of
fistula tracts difficult.
oxide (Figure 13-12b) or Levovist™
41
The concomitant use of hydrogen per-
43
at the time of ultrasound
examination has been found to improve its accuracy.
Magnetic Resonance Imaging
MRI in the form of endoanal coil, body coil, and phase array
coil (Figure 13-13) may be of value in the assessment of
patients with complex fistulas and in those with anatomic
distortion resulting from previous surgery. Because MRI can
provide multiplanar visualization of the sphincter muscles,
differentiation of supralevator from infralevator lesions is eas-
44
MRI has been found to accurately delineate the presence
ier.
and course of a primary fistulous tract but also demonstrates
the site and presence of any secondary extensions.
45
It also
provides the most accurate imaging technique of localizing
the site of the internal opening because its location can be
inferred from the proximity of the tract in the intersphincteric
45
space.
A prospective study that compared the accuracy of
MRI in the preoperative assessment of anal fistulas to operative findings found concordance rates of 88% for the presence
and course of the primary tract, 91% for the presence and site
of secondary extensions or abscesses and 97% for the presence of horseshoeing, and 80% for the position of the internal
openings.
45
In the same study, failure of healing in 9% was
found to be related to pathology missed at the time of surgery
which had been documented on preoperative MRI.
Difficulties in interpretation, however, may occur because
neural and vascular structures could be mistaken for fistulas
and chemical shift artifacts may simulate a fistula filled with
46
fluid.
The use of the endoanal coil has been found to be
superior to external MRI for the identification of complex
sphincter anatomy especially in the demonstration of the morphology of the internal and external sphincters
47
; however,
definition may fall off outside the sphincter and may fail to
show the tracts that lie beyond its range. It is also painful. A
prospective study comparing hydrogen peroxide endoanal
ultrasound to endoanal MRI found good agreement for the
classification of the primary fistula tract and the location of
the internal opening. These results also demonstrated good
agreement with the surgical findings enabling both to be reliable for the preoperative evaluation of fistulas.
48
45
FIGURE 13-12. A Anal endosonogram; arrows indicate fistula tract; B with hydrogen peroxide; arrows indicate better delineation of fistula
tract. (Courtesy Dr. Julio Faria.)
202 C.-A. Vasilevsky and P.H. Gordon
FIGURE 13-13. Phase array MRI. A White arrowhead indicates levators; black arrowhead indicates fistula tract to rectum; black arrow shows
tract crossing levator. B Arrowhead indicates tract going to skin.
A prospective trial comparing the use of the endoanal coil
to the body coil found that surgical concordance for the
endoanal coil was 68% versus 96% for the body coil, presumably because of field of view limitations.
49
This can be
overcome with the use of the phase array coil which has a
larger field of view and may be useful in Crohn’s disease and
recurrent fistulas.
50
the dentate line. Although methylene blue may stain surrounding tissues, diluting it with saline or hydrogen peroxide will obviate this problem.
3. Following the granulation tissue present in the fistula tract.
4. Noting puckering of an anal crypt when traction is placed
on the tract. This may be useful with simple fistulas but is
less successful in the more complicated varieties.
Buchanan et al.,51in a prospective study to determine the
impact of MRI with primary fistulas, found that MRI changed
the surgical approach in 10%. In another study with respect to
recurrent fistulas, recurrence rates were found to be higher for
those surgeons who never used MRI.
52
They concluded that
MRI-guided surgery can decrease recurrence rates by 75% in
surgery for recurrent fistulas.
Treatment
General Principles
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.
Several methods have been proposed to identify the pri-
mary opening in the operating room
1. Passage of a probe or probes from the external opening to
the internal opening or vice versa.
2. Injection of a dye such as dilute solution of methylene blue,
milk, or hydrogen peroxide, and noting their appearance at
1,4
:
Operative Management
Lay-open Technique
For the treatment of simple intersphincteric and low
transsphincteric fistulas, the patient is placed in the prone jackknife position after induction of a regional anesthetic. Local
anesthesia consisting of 0.5% lidocaine or 0.25% bupivacaine
hydrochloride with 1:200,000 epinephrine is injected along the
fistula tract for hemostasis after insertion of an anal speculum.
Use of bupivacaine provides analgesia of longer duration than
most regional anesthetics. A probe is inserted from the external opening along the tract to the internal opening at the dentate line. The tissue overlying the probe is incised and the
granulation tissue curetted and sent for pathologic evaluation.
A gentle probe is used to identify any high blind tracts or
extensions, which are unroofed, if found. If desired, the wound
may be marsupialized on either edge by sewing the edges of
the incision to the tract with a running locked absorbable
suture. There is no need to insert packing if an adequate
unroofing has been accomplished (Figure 13-14A–C).
13. Benign Anorectal: Abscess and Fistula 203
Seton
The problem of preserving anal continence and treating the
fistula is more complicated when managing high transsphincteric fistulas. If the tract is seen to cross the sphincter muscle
at a high level, the use of the lay-open technique in combination with insertion of a seton is safer. A seton may be any foreign substance that can be inserted into the fistula tract to
encircle the sphincter muscles. Materials frequently used
include silk or other nonabsorbable suture material, Penrose
drains, rubber bands, vessel loops, and silastic catheters.
The lower portion of the internal sphincter is divided along
with the skin to reach the external opening and a nonabsorbable suture or elastic suture is inserted into the fistulous
tract. The ends of the suture or elastic are tied with multiple
knots to create a handle for manipulation (Figure 13-15). This
form of seton, known as a cutting seton, is tightened at regular intervals to slowly cut through the sphincter. This allows
the tract to become more superficial, converting a high fistula
into a low one. The proximal fistulotomy subsequently heals
by stimulating fibrosis behind it reestablishing continuity of
the anorectal ring to prevent separation of the sphincter muscle at a second-stage repair 8 weeks later when the remaining
external sphincter is divided. The seton also allows delineation of the amount of remaining muscle thus enabling
improved postoperative assessment by outlining the tract. A
seton may also be used as a drain which is left loosely in place
to facilitate prolonged drainage. Specific indications for seton
use include the following:
53
1) to identify and promote fibrosis around a complex anal fistula that encircles most or all of
the sphincter mechanism; 2) to mark the site of a transsphincteric fistula in cases of massive anorectal sepsis where the
normal anatomic landmarks have been distorted; 3) anterior,
high transsphincteric fistulas in women. Because the
17
FIGURE 13-14. Technique of laying open. A Insertion of probe and
incision of tissue overlying probe. B Curettage of granulation tissue.
C Marsupialization of wound edges.
FIGURE 13-15. Seton.
204 C.-A. Vasilevsky and P.H. Gordon
puborectalis is absent in this area and the external sphincter is
quite tenuous, primary fistulotomy may result in incontinence; 4) the presence of a high transsphincteric fistula in a
patient with AIDS in whom healing is known to be poor; 5)
to avoid premature skin closure and formation of recurrent
abscesses and promote long-term drainage in patients with
Crohn’s disease. In these patients, a silastic catheter can be
left in place for a prolonged period of time to promote epithelialization of the fistula tract or tracts; 6) when there is suspicion that primary fistulotomy will result in incontinence such
as in those patients with multiple simultaneous fistulas,
patients who have undergone multiple prior sphincter operations such as fistulotomy or internal sphincterotomy, and in
elderly patients with weakened sphincter muscles.
Another option available to treat transsphincteric fistulas
without division of muscle involves the use of a dermal island
54
flap.
Division of muscle was able to be avoided in 90%;
however, a 23% failure rate was reported. This was found to
be more likely in males, patients who had previous treatment
of their fistulas, patients with large fistulas requiring combined flaps, and patients who underwent simultaneous fibrin
glue injection.
Treatment of suprasphincteric fistulas requires an appreciation that the tract involves the entire external sphincter complex as well as the puborectalis muscle. Laying open the
entire tract would render the patient incontinent. Thus, several
methods have been proposed to manage this fistula without
the ensuing devastating consequences. The use of a seton has
been advocated in combination with division of the internal
sphincter and the superficial portion of the external sphincter
to the external opening. The seton is placed around the
remaining external sphincter as was previously described.
55
A modification of this approach has been proposed by
Kennedy and Zegarra
56
in which an internal sphincterotomy is
performed, followed by opening of the tracts outside the
external sphincter without division of any portion of the external sphincter which is encircled by a seton to promote fibrosis and assure adequate drainage. Complete healing using the
latter approach has been reported in 66% with posterior fistulas and in 88% with anterior fistulas.
56
Parks and Stitz
obtained healing in 63%. Another method that has been proposed to treat this type of fistula is the anorectal advancement
flap which will be described.
The horseshoe variety of the suprasphincteric fistula also
presents the problem of complete sphincter involvement combined with the presence of multiple external openings a great
distance from the cryptoglandular source. Treatment consists
of identification of the internal opening and proper drainage
of the postanal space as was previously described. The horseshoe extensions are enlarged for counter-drainage and the
granulation tissue is curetted.
The treatment of an extrasphincteric fistula depends on its
etiology. If the fistula arises secondary to an anal fistula, a
secondary opening above the puborectalis is thought to be
iatrogenic because of extensive probing of a transsphincteric
fistula. The lower portion of the internal sphincter is divided
and the rectal opening is closed with a nonabsorbable suture.
A temporary colostomy may be necessary but a medical
colostomy consisting of preoperative mechanical and antibiotic bowel preparation followed by enteral feeding may suffice. If the fistula is the result of entrance of a foreign body, it
must be removed, drainage must be established, the internal
opening closed, and a temporary colostomy constructed to
decrease rectal pressure. This type of fistula may also be a
manifestation of Crohn’s disease. Treatment will depend on
the nature of the anorectal mucosa and drainage may be
assisted by placement of a seton. Finally, the fistula may be
the result of downward tracking of a pelvic abscess which
must be drained so that the fistula can heal.
Anorectal Advancement Flap
When the traditional laying-open technique may be inappropriate, for example, in anterior fistulas in women, in patients
with inflammatory bowel disease, in patients with high
transsphincteric and suprasphincteric fistulas, as well as in
those with previous multiple sphincter operations, multiple
and complex fistulas, the use of an anorectal advancement
57
flap has been advocated
(Figure 13-16A–D). Advantages of
this technique include a reduction in the duration of healing,
reduced associated discomfort, lack of deformity to the anal
canal, as well as little potential additional damage to the
sphincter muscles because no muscle is divided.
17
After full mechanical and antibiotic bowel preparation, the
patient is placed in the prone jackknife or left lateral position.
Under a regional or general anesthetic, after insertion of a
Foley catheter, the fistula tract is identified with a probe and
either cored out or curetted. The internal opening is identified
and excised. The external opening is enlarged to allow for
drainage. A full-thickness flap of rectal mucosa, submucosa,
and part of the internal sphincter is raised. The residual internal opening is closed with absorbable suture. The flap is then
advanced 1 cm below the internal opening. The tip of the flap
containing the fistulous opening is excised and the flap is
sewn into place with absorbable sutures ensuring that the
55
mucosal and muscular suture lines do not overlap. The base
of the flap should be twice the width of the apex to maintain
good blood supply. Successful results have reported in more
than 90% of patients.
include Crohn’s disease and steroids.
58
Factors associated with poor outcomes
59
Cigarette smoking was
found to be another significant variable in another study.
Fistulectomy
Although excision of the fistula or fistulectomy was thought
to be a satisfactory method of treatment of fistula-in-ano, its
use is no longer recommended. Larger wounds are created
significantly prolonging wound healing time.
aration of muscle ends occurs
1
and there is greater risk of
injuring or excising underlying muscle
61
A greater sep-
57
thereby increasing
the risk of incontinence. Schouten and van Vroonhoven
60
14
13. Benign Anorectal: Abscess and Fistula 205
FIGURE 13-16. Anorectal advancement flap. A Transsphincteric fistula-in-ano. B Enlargement of external opening and curettage of granulation tissue. C Mobilization of flap and closure of internal opening. D Suturing of flap in place covering internal opening.
have found that fistulectomy, whether primary or secondary,
was associated with a clinically significant disturbance in anal
function.
with its internal and external openings is identified and curetted (with curettes or flexible brushes). Fibrin glue is injected
into the fistula tract through a Y connector so that the entire
tract is filled and the glue can be seen emerging from the
Fibrin Glue
The use of fibrin glue as a primary treatment alone or in combination with an advancement flap has come into vogue. This
treatment modality is appealing because it is a noninvasive
approach that avoids the risk of incontinence associated with
fistulotomy. In the case of failure, it may be repeated several
times without jeopardizing continence. The technique
involved is simple. As with fistulotomy, the fistula tract along
internal opening. The injecting catheter is slowly withdrawn
so that the entire tract is filled. Petrolatum jelly gauze may be
placed over the external opening.
Enthusiasm generated because of short-term success rates
of 70%–74%
tula recurrence despite initial apparent healing.
62,63
has been tempered because of delayed fis-
64
With longer
follow-up, 60% of fistulas were found to have healed in a
65
recent study
although patients underwent a two-stage
approach consisting of seton placement followed by glue
206 C.-A. Vasilevsky and P.H. Gordon
injection at a second stage. Patients who failed underwent
repeat injection which allowed 69% to heal. The 29% who
failed to heal underwent either fistulotomy or advancement
flap. Late recurrences (6%) occurred more than 6 months
postoperatively and were treated with reinjection. Buchanan
66
et al.
found fibrin glue injection to be useful in 14% with
complex anal fistulas without extensions.
Although the exact mechanisms responsible for failure
have not been entirely appreciated, it has been suggested that
curettage may not adequately remove all granulation or
epithelialized tissue thus failing to provide the correct environment for the glue to work.
66
Other adverse factors shown
to influence healing include the presence of a short tract
which may make it easier for the fibrin glue plug to become
dislodged as well as the presence of a cavity on endoanal
ultrasound.
67
The latter was associated with a complication of
perianal abscess because the tract may not have been entirely
filled with glue.
68
It has been suggested that fibrin glue be
considered as first-line treatment for complex anal fistulas in
appropriately selected patients.
Bioprosthetic Fistula Plug
Recently, the use of a bioprosthetic plug made from
lyophilized porcine intestinal submucosal has been described
for complex anal fistulas.
anal fistula plug) is commercially available from Cook
Surgical Inc, Bloomington, IN. Following rehydration of the
plug, the following technique is used. The fistula tract is identified but not debrided. A solution of peroxide may be used to
gently clean the tract. A fistula probe is placed through the
tract and a 2–0 suture is placed through the tapered end of the
plug and the ends of this suture are attached to the fistula probe
at the primary opening. The suture is pulled from the primary
opening, through the fistula tract to exit at the secondary opening. For patients with a “horseshoe” fistula, an incision is made
over the fistula tract distal to the anal verge to create a secondary opening that the ends of the suture are brought through.
With gentle traction on the suture, the porcine plug is pulled
into the primary opening of the fistula until “wrinkling” of the
superficial layer of the plug is first seen. The plug is not forced
tightly. Excess plug is removed by transecting the plug at the
level of the primary opening. The plug is secured in the primary opening using a 2– 0 absorbable suture placed in a figure
of 8 fashion with the suture crossing through the center of the
plug and incorporating a generous portion of the sphincter
mechanism on both sides. Any plug protruding through the
secondary opening is also excised. The distal end of the plug
is not sutured to the fistula tract and the distal opening is left
open for drainage. Patients are advised to avoid vigorous physical activity for two weeks after plug placement to minimize
the chance of plug dislodgement.
The prospective study by Johnson, et al., compared the
procine plug to fibrin glue in twenty-five patients with high
transsphincteric or deeper fistuals.
117
This porcine fistula plug (Surgisis
117
Patients with Crohn’s dis-
ease or superficial fistulas were excluded. Ten patients underwent fibrin glue closure, and 15 used a fistula plug. Patient’s
age, gender, fistula tract characteristics, and number of previous
closure attempts was similar in both groups. In the fibrin glue
group, six patients (60 percent) had persistence of one or more
fistulas at three months, compared with two patients (13 percent) in the plug group (p < 0.05, Fisher exact test). The authors
concluded that closure of the primary opening of a fistula tract
using a suturable biologic anal fistula plug is an effective
method of treating anorectal fistulas.
The technique has appeal for its simplicity and avoidance
of sphincter injury. The technique seems to work best with
long tracts without active sepsis. It is not suitable for short
rectovaginal fistulas. An additional limitation has been the
relatively high cost of the plug and the lack of large scale controlled multi-center trials. Although the early has been positive, further prospective, long-term studies are warranted.
Postoperative Care
After the lay-open technique, patients are placed on regular
diets, bulk agents, and non-codeine-containing analgesia.
Patients are instructed to take frequent sitz baths to ensure
perianal hygiene. Patients are evaluated at 2-week intervals to
ensure that healing has occurred from the depths of the tract.
Granulation tissue can be cauterized using silver nitrate sticks
and cotton-tipped swabs are often used to probe the depths of
the incision to ensure that adequate healing is occurring.
After the advancement flap technique, the Foley catheter is
removed on the following day. The authors prefer to maintain
patients on intravenous therapy and no oral nutrition for 5
days to allow adequate healing of the flap. After elapse of this
time, the diet is progressed and routine management is instituted. The editor (D.E.B.) prefers to feed patients as soon as
they can tolerate a diet.
Complications
Incontinence
Minor disorders of continence after fistulotomy have been
reported to range from 18% to 52% whereas soiling and
insufficiency have been reported in as many as 35% to 45%
(Table 13-3). The occurrence of continence disorders has
been found to be related to the complexity of the fistula and
to the level and location of the internal opening.
69
Patients with complicated fistulas, high openings, posterior
openings, and fistula extensions have been found to be at
higher risk.
69
In the treatment of complicated fistulas and
those with high openings, more muscle is divided, thus
decreasing anal pressures whereas posterior fistula wounds
have been associated with higher rates of incontinence
because of their more circuitous routes.
69
Drainage of exten-
sions may accidentally damage small nerves and create
69
more scar tissue around the anorectum.
If the edges of the
69
13. Benign Anorectal: Abscess and Fistula 207
TABLE 13-3. Results of Fistula Surgery
Author Year No. of patients Recurrence (%) Incontinence (%)
Marks and Ritchie
Vasilevsky and Gordon
11
Fucini
69
Van Tets
72
Sangwan
Garcia-Aguilar et al.
Mylonakis et al.
Malouf et al.
Westerterp et al.
*
3% solid stool, 17% liquid stool, 25% flatus.
†0.7% solid stool, 2.0% liquid stool, 3.3% flatus.
‡0% solid stool, 0.2% liquid stool, 0.5% flatus.
§0% solid stool, 6.0% soiling, 3.0% gas.
70
71
73
74
75
76
1977 793 — 3, 17, 25
1985 160 6.3 0.7, 2.0, 3.3†
1991 99 3.0 0, 0.2, 0.5‡
1994 19 — 33.0
1994 461 6.5 2.8
1996 293 7.0 42.0
2001 100 3.0 0, 6.0, 3.0§
2002 98 4.0 10
2003 60 0 50
*
fistulotomy wound do not approximate precisely, the anus
may be unable to properly close, resulting in intermittent
leakage of gas and stool.
impaired continence was associated with increasing age
female gender.
69,70
The latter is probably the result of partial
53
In addition to these factors,
70
and
anal sphincter disruption and/or traction injury to the pudendal nerves sustained during vaginal delivery.
70
Although excellent results using a seton have been
reported,
impaired continence.
reported in 73%
disturbances in 54%. Parks and Stitz
77
its use does not protect against the development of
69
69
Minor continence disorders were
whereas Williams et al.78reported minor
55
found that minor
incontinence occurred in 39% with the two-stage approach
versus 17% when only the first stage was performed and the
seton was removed rather than dividing the muscle. Major
fecal incontinence was reported in 6.7%
53
after a review of
several series (Table 13-4). The degree of incontinence is
thought to be influenced by the patient’s preoperative state of
control as well as to how the anal wound heals.
53
Excellent
results with respect to continence have been reported with the
use of the advancement flap
observed disturbances in continence in 9%–35%.
59
although recent reports have
82,83
Recurrence
Recurrence rates after fistulotomy range from 0% to 18%.
72
Results from selected references are cited in Table 13-3.
Causes include failure to identify a primary opening or
recognize lateral or upward extensions of a fistula.
TABLE 13-4. Results of staged fistulotomy using a seton
Author Year Recurrence (%) Incontinence (%)
77
Ramanujam et al.
Fasth et al.
Williams et al.
Pearl et al.
Van Tets
Graf et al.
Garcia-Aguilar et al.
Hasegawa et al.
79
78
53
69
80
81
1983 1/45 (2) 1/45 (2)
1990 0/7 (0) 0/7 (0)
1991 2/28 (8) 1/24 (4)
1993 3/116 (3) 5/116 (5)
1994 — 15/29 (54)
1995 2/25 (8) 11/25 (44)
73
1996 6/63 (9) 39/61 (64)
2000 8/32 (25) 15/32 (4.8)
71,72
Inability to locate the primary opening may imply a circuitous
72
tract,
microscopic opening.
spontaneous closure of the primary opening,71or a
72
The presence of secondary tracts
which can be easily missed accounted for early recurrence in
72
20%.
Premature closure of the fistulotomy wound can be
obviated by producing an external wound twice the size of the
anal wound resulting in proper healing of the internal wound
before the external wound.
72
Diligent postoperative care can
also reduce recurrence rates by avoiding bridging and pocketing of the wound.
84
Epithelialization of the fistula tract from
internal or external openings rather than chronic infection of
an anal gland has also been suggested as the cause of a persistent anal fistula.
85
Recurrence rates after staged repairs using a seton range
from 0% to 29%.
53
Results from selected references are cited
in Table 13-4.
Although recurrence rates after anorectal advancement flaps
were initially reported to be low, with long-term follow-up,
recurrence rates of 40% have been reported.
83
Recurrence can
be minimized provided that care has been taken to avoid necrosis or retraction of the flap. The use of full-thickness rectal wall
has been advocated to prevent ischemic necrosis of the flap.
86
Early postoperative complications that have been reported
after fistula surgery include urinary retention, hemorrhage,
fecal impaction, and thrombosed external hemorrhoids, which
were found to occur in less than 6% of cases.
18
Later complications such as pain, bleeding, pruritus, and poor wound healing have been reported in 9% of patients.
57
Anal stenosis may
occur and is usually the result of loose stools allowing healing
of the anal canal by scar contracture.
35
Mucosal prolapse
caused by extensive division of sphincter muscle may also
occur and can be treated by band ligation, sclerosis, or exci-
57
sion.
With attention to both operative detail and postoperative
follow-up, these complications can be reduced to a minimum.
Special Considerations
Crohn’s Disease
Anal fistulas are the most difficult and challenging complication of Crohn’s disease to manage. They constitute the most
71
208 C.-A. Vasilevsky and P.H. Gordon
common perianal manifestations, occurring in 6%–34% of
patients.
87
The location of Crohn’s disease in the bowel has an
impact on the frequency of fistulas. Patients with colonic
Crohn’s have a higher incidence with the rate approaching
100% in those with rectal Crohn’s.
88
As discussed previously, patients with Crohn’s disease
should undergo sigmoidoscopy, colonoscopy, and small
bowel follow through to determine the extent of disease.
Delineation of the fistulous tract is especially important in
Crohn’s disease because many fistulas may be complex in
nature. In this context, endoanal ultrasound has been found to
be as useful as MRI. MRI has been found to detect abscesses
that were clinically unsuspected on clinical examination
89
and
has been helpful in determining the relationship of the fistulous tract to the sphincter muscles.
Therapeutic goals in managing anorectal fistulas in Crohn’s
disease remain the alleviation of symptoms and preservation
of continence. Surgical treatment of fistulas is associated with
poor and delayed wound healing and with the risk of sphincter injury. Alexander-Williams stated that “incontinence is
likely to be the result of aggressive surgeons, not of aggressive disease.” A conservative approach has therefore been
advocated, especially because 38% of such fistulas have been
reported to heal spontaneously without any surgical interven-
90
tion.
Medications used in the treatment of fistulas include
antibiotics such as metronidazole and ciprofloxacin and
immunomodulators such as corticosteroids, 6MP, azathioprine, and infliximab. Although several studies have reported
spontaneous closure of fistulas in 34%–50% of patients
treated with metronidazole,
88
improvement is usually seen
after 6–8 weeks of treatment with relapses common once the
medication is discontinued. A recent study that looked at the
long-term effects of 6MP and azathioprine found that these
medications were efficacious in only one-third of patients
with fistulizing perianal disease.
91
These effects seemed unrelated to their effects on intestinal disease. The authors concluded that their results did not support the use of these
medications solely for the improvement of perianal disease.
The use of infliximab has been associated with a 62% reduction in draining fistulas.
92
The combination of infliximab and
6MP may prolong the effect of initial infliximab treatment on
fistula closure.
93
Selective seton placement combined with
infusion of infliximab and maintenance therapy with azathioprine or methotrexate resulted in complete healing in 67%
with Crohn’s fistulas in a recently reported retrospective
94
study.
Maintenance therapy with infliximab has been
reported to result in absence of draining fistulas in 36% of
patients compared with 19% in placebo patients at 54-week
follow-up.
95
Although fistulas may occur in as many as 73% of patients
after previous abscess drainage,
87
it is imperative that primary
fistulotomy not be performed because of the high risk of creating false passages and injuring the sphincter mechanism.
Asymptomatic fistulas require no treatment. Low fistulas with
simple tracts can be managed with the standard lay-open
method in the absence of active proctitis. Successful outcome
as gauged by healing has been reported to occur in
42%–100%, mostly in the 70%–80% range of procedures.
96
The advent of fibrin glue has certainly offered another
option in the armamentarium of treating fistulous Crohn’s disease. A closure rate of 60% has been reported in one study.
97
This may also be combined with an endorectal advancement
flap in the absence of rectal involvement.
Fistulotomy has been associated with prolonged healing.
98
Factors associated with delayed healing are rectal involve-
10,73
ment,
anorectal complications (especially strictures),
and the presence or absence of an internal opening.
98
99
Successful healing has occurred in patients with a classic internal opening at the dentate line and in those without rectal
99
involvement
although Halme and Sainio98found that delayed
healing occurred in 80% of patients despite the presence of a
normal rectum; Van Dongen and Lubbers
100
found no difference in healing even in the presence of rectal involvement.
Nonetheless, initial therapy should be directed at resolving
inflammation in the rectum. This can be accomplished with
the use of topical steroid or 5-acetylsalycylic enemas or suppositories. In addition, oral medication may be necessary.
Incontinence has been reported in patients with proctitis
who have not undergone anal surgery.
100
A patient with severe
rectal involvement and even a simple low fistula is not a candidate for fistulotomy. Division of any sphincter muscle in
this situation may result in frank incontinence because the
noncompliant rectum acts as a conduit rather than as a reservoir. Continence problems have been reported in 25% of
patients after simple incision and drainage of abscesses during which the sphincter mechanism has not been touched.
Allan and Keighley
101
reported a 50% frequency of major
100
fecal incontinence and minor incontinence has been described
in 33% of patients who have undergone only simple drainage
or local surgery.
98
It is thought that diarrhea from either associated intestinal involvement or multiple previous small
bowel resections is important in control disorders in these
patients.
87,98,100
Appropriate medical therapy should be used
to control the diarrhea.
Complex fistulas with high rectal openings might best be
managed conservatively, because impaired continence may
certainly result if the sphincter muscle is divided. Eradication
of the fistula in this situation may not be possible because of
the complexity of the tracts. Seton placement has been advocated to promote drainage, limit recurrent suppuration, and
preserve sphincter function.
been used in the absence of severe rectal disease.
102
Rectal advancement flaps have
103
These
have been found to succeed in patients without concomitant
small bowel Crohn’s.
104
The importance of quiescent intestinal disease for success-
ful outcome of local fistula surgery has been suggested
105
but
not generally accepted and practical. Proximal fecal diversion
has also been suggested as an option to ameliorate severe
perianal disease because diversion of the fecal stream may
reduce perianal inflammation. However, improvement is
13. Benign Anorectal: Abscess and Fistula 209
temporary because fistulas will reactivate after restoration of
intestinal continuity.
106
Complicated fistulas are more likely to recur because of the
reluctance of the surgeon to divide sphincter muscle. The use
of a long-term in-dwelling seton as a drain is therefore recommended.
102
Fistula recurrence may be as high a 39% after
removal of the seton and may necessitate the use of concomitant medical therapy.
87
The use of a rectal advancement flap
has been successful; however, breakdown is possible because
of sepsis.
has been reported.
103
In patients with mild proctitis, a 20% success rate
103
The presence of a protective stoma in
this situation does not guarantee success, with failure reported
in 55% of patients.
103
A covering stoma may be beneficial in
the patient who has undergone multiple unsuccessful
103
repairs.
achieve complete healing
Many fistulas may require repeat fistulotomy to
98
or repeat injections of fibrin glue.
For severe intractable disease, an intersphincteric proctectomy may ultimately become necessary. The intersphincteric
technique reduces the size of the resulting wound and reduces
the incidence of unhealed sinuses.
Fistula-in-ano in the HIV-positive Patient
Anal fistulas are prevalent in the anoreceptive HIV-positive
individual.
infection to occur.
107
Disturbed locoregional defenses may allow
107
Although anal fistulas in HIV-positive
patients arise from the dentate line similar to those in HIVnegative patients, they are more likely to have incomplete
anal fistulas leading to blind sinus tracts.
108
Concern for
wound healing has tempered enthusiasm for operative intervention. However, selective operative management will
result in a high rate of complete or partial wound healing
with symptomatic relief without excessive morbidity or mor-
107
tality.
Severity of illness must be assessed before operative
intervention because patients with more advanced disease are
less likely to heal their wounds. Data are conflicting as to
whether preoperative CD4+ lymphocyte counts can be
related to poor wound healing
107
; however, Consten et al.
found that low CD4+ lymphocyte counts in patients with
perianal sepsis were a risk factor for disturbed wound healing. Use of Highly Active Antiviral therapy (HAART) may
reduce the incidence of opportunistic infections and anorectal disease and aid healing.
109
Asymptomatic fistulas require no treatment. Perioperative
antibiotic therapy over a 5-day course has been recommended
because of the high risk of infectious complications.
107
Care
should be exercised to avoid creation of large wounds and to
preserve as much sphincter muscle as possible because these
patients may be prone to diarrhea which may overwhelm a partially divided sphincter.
107
In patients who are good operative
risks, fistulotomy is appropriate in patients with intersphincteric or low transsphincteric fistulas. For high or complex fistulas as well as for those patients who are poor operative risks,
liberal use of draining setons is recommended.
35,107
It is impor-
tant to realize that cellulitis may be seen with a fistula without
107
concomitant underlying exudate.
Metastatic abscesses to
other organs including brain, liver, and mediastinum have been
reported with asymptomatic perianal fistulas.
been reported in 55%–80% of patients.
31,107
31
Healing has
Rectourethral Fistulas
Pathophysiology
Rectourethral fistulas are rare but devastating complications
that may occur after radical prostatectomy, radiation treatment for prostate cancer, trauma, recurrent perineal abscess,
or after treatment with radiofrequency hyperthermia for
benign prostatic hypertrophy. It may occur after trauma, as a
result of Crohn’s disease.
The prostatic urethra is the most common site for fistulization to occur because this portion of the urethra is adjacent to
the rectal wall.
Evaluation and Treatment
Symptoms
The most common symptoms include leakage of urine
through the rectum during voiding, pneumaturia, and
fecaluria. These symptoms will tend to occur during the early
postoperative period after prostatectomy. In addition, recurrent urinary tract infections resistant to antibiotic treatment
after one of the aforementioned causes should suggest this
diagnosis.
Investigations
Prostate-specific antigen determination should be done to rule
out recurrence of carcinoma. Digital rectal examination
should always be performed to determine if there is any
anorectal pathology that could be the cause. Sigmoidoscopy
31
will show the fistula opening which is located on the anterior
rectal wall and in addition rule out rectal pathology as a
source. Cystoscopy and retrograde urethral cystography
should be performed to determine the presence of a urethral
stricture. Assessment of urinary continence should be done
before any attempt at surgical repair.
Operative Treatment
Operative repair of rectourethral fistulas is challenging
because of technical difficulties that are often encountered as
a result of difficult exposure. Multiple repairs have been
developed but there is no consensus as to which is best.
Traditionally, it has been suggested that the first attempt at
repair is the best and that subsequent repairs become more
difficult.
colostomy or ileostomy and urinary diversion with suprapubic
110
Treatment consisting of fecal diversion with either
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