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296 The ASCRS Manual of Colon and Rectal Surgery
• A seton may also be used as a drain which is left loosely in
place to facilitate prolonged drainage.
• Specifi c indications for seton use include the following:
– To identify and promote fi brosis around a complex anal fi s-
tula that encircles most or all of the sphincter mechanism.
– To mark the site of a transsphincteric fi stula in cases
of massive anorectal sepsis where the normal anatomic
landmarks have been distorted.
– Anterior, high transsphincteric fi stulas in women.
Because the puborectalis is absent in this area and the
external sphincter is quite tenuous, primary fi stulotomy
may result in incontinence.
– The presence of a high transsphincteric fi stula in a patient
with AIDS in whom healing is known to be poor.
– To avoid premature skin closure and formation of recur-
rent 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 fi stula tract or tracts.
– When there is suspicion that primary fi stulotomy will
result in incontinence such as in those patients with multiple simultaneous fi stulas, patients who have undergone
multiple prior sphincter operations such as fi stulotomy
or internal sphincterotomy, and in elderly patients with
weakened sphincter muscles.
• Another option available to treat transsphincteric fi stulas without division of muscle involves the use of a dermal island fl ap.
• The horseshoe variety of the suprasphincteric fi stula 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 identifi cation 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.
Anorectal Advancement Flap
• When the traditional laying-open technique may be inappropriate,
for example, in anterior fi stulas in women, in patients with infl ammatory bowel disease, in patients with high transsphincteric and
suprasphincteric fi stulas, as well as in those with previous multiple
13. Benign Anorectal: Abscess and Fistula 297
sphincter operations, multiple and complex fi stulas, the use of an
anorectal advancement fl ap has been advocated (Fig. 13.13 a – 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.
• The base of the fl ap should be twice the width of the apex to
maintain good blood supply. Successful results have reported
in more than 90% of patients.
• Factors associated with poor outcomes include Crohn’s disease and steroids. Cigarette smoking was found to be another
signifi cant variable in another study.
Fistulectomy
• Although excision of the fi stula or fi stulectomy was thought
to be a satisfactory method of treatment of fi stula-in-ano, its
Fig. 13.13. Anorectal advancement fl ap. ( a ) Transsphincteric fi stula-in-ano.
( b ) Enlargement of external opening and curettage of granulation tissue.
( c ) Mobilization of fl ap and closure of internal opening. ( d ) Suturing of fl ap in
place covering internal opening.
298 The ASCRS Manual of Colon and Rectal Surgery
use is no longer recommended. Larger wounds are created
signifi cantly prolonging wound healing time. A greater separation of muscle ends occurs and there is greater risk of injuring
or excising underlying muscle thereby increasing the risk of
incontinence.
Fibrin Glue
• This treatment modality is appealing because it is a noninvasive approach that avoids the risk of incontinence associated
with fi stulotomy. In the case of failure, it may be repeated
several times without jeopardizing continence.
• Enthusiasm generated because of short-term success rates of
70–74% has been tempered because of delayed fi stula recurrence despite initial apparent healing. Closure rates as low as
15% have been reported.
• Suggested reasons for failure include inadequate curretage of
the tract, presence of a short tract and presence of a cavity on
endoanal ultrasound.
Bioprosthetic Fistula Plug
• Recently, the use of a bioprosthetic plug made from lyophilized
porcine intestinal submucosal has been described for complex
anal fi stulas.
• The technique involves preoperative enemar prior to the procedure. Patients are given intravenous metronidazole just prior
to the start of the procedure. Fistula tracts are irrigated with
hydrogen peroxide prior to insertion of the tract. The plug is
rehydrated in sterile saline and a 2-0 vicryl is secured to the
tapered end of the plug. The ends of the suture are attached to a
fi stula probe at the primary opening. The suture is then pulled
from the primary opening to exit at the secondary opening.
Excess plug at the internal opening is trimmed fl ush with the
mucosa and the plug is sutured deep to the internal sphincter
with a fi gure of eight 2-0 absorbable suture. A small mucosal
advancement fl ap may be placed over the top of the plug to
ensure that it is buried in the tract. Any excess plug is excised
at the secondary opening which is left open to allow drainage.
• Patients are advised to avoid vigorous physical activity for two
weeks after plug placement to minimize the chance of plug
dislodgement.
13. Benign Anorectal: Abscess and Fistula 299
• The technique seems to work best with long tracts without active
sepsis. It is not suitable for short rectovaginal fi stulas. An additional limitation has been the relatively high cost of the plug.
• A recent prospective study demonstrated 84% early healing.,
Longer follow-up was associated with progressively increasing failure rates of 27.2% at 8 weeks, 38.6% at 12 weeks and
45.4% at 13 months High failure rate was associated with complex fi stulas and patients with Crohn’s Disease.
• Another recent prospective study found that the use of the fi stula
plug was associated with a low rate of healing and a high rate
of perianal sepsis. There was a suggestion of increased healing
without complication in patients who underwent a concomitant
advancement fl ap.
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 fl ap technique, the Foley catheter is
removed on the following day. The authors prefer to maintain
patients on intravenous therapy with no oral nutrition for 5
days to allow adequate healing of the fl ap. Several of the editors do not limit oral intake in the postoperative period, which
signifi cantly shortens the hospital stay.
Complications
Incontinence
• Minor disorders of continence after fi stulotomy have been
reported to range from 18 to 52% whereas soiling and insuffi ciency have been reported in as many as 35–45% (Table 13.3 ).
The occurrence of continence disorders has been found to be
related to the complexity of the fi stula and to the level and location of the internal opening.
300 The ASCRS Manual of Colon and Rectal Surgery
Table 13.3. Results of fi stula surgery.
No. of
Author Year
Marks and Ritchie 1977 793 – 3, 17, 25
Vasilevsky and Gordon 1985 160 6.3 0.7, 2.0, 3.3
Fucini 1991 99 3.0 0, 0.2, 0.5
Van Tets 1994 19 – 33.0
Sangwan 1994 461 6.5 2.8
Garcia-Aguilar et al. 1996 293 7.0 42.0
Mylonakis et al. 2001 100 3.0 0, 6.0, 3.0
Malouf et al. 2002 98 4.0 10
Westerterp et al. 2003 60 0 50
a
3% solid stool, 17% liquid stool, 25% fl atus
b 0.7% solid stool, 2.0% liquid stool, 3.3% fl atus
c 0% solid stool, 0.2% liquid stool, 0.5% fl atus
d 0% solid stool, 6.0% soiling, 3.0% gas
patients
Recurrence
(%)
Incontinence
(%)
• Patients with complicated fi stulas, high openings, posterior
openings, and fi stula extensions have been found to be at
higher risk.
• In the treatment of complicated fi stulas and those with high openings, more muscle is divided, thus decreasing anal pressures
whereas posterior fi stula wounds have been associated with higher
rates of incontinence because of their more circuitous routes.
• If the edges of the fi stulotomy wound do not approximate precisely, the anus may be unable to properly close, resulting in
intermittent leakage of gas and stool. In addition to these factors, impaired continence was associated with increasing age
and female gender. The latter is probably the result of partial
anal sphincter disruption and/or traction injury to the pudendal
nerves sustained during vaginal delivery.
• Although excellent results using a seton have been reported,
its use does not protect against the development of impaired
continence.
• Major fecal incontinence was reported in 6.7% after a review
of several series (Table 13.4 ). The degree of incontinence is
thought to be infl uenced by the patient’s preoperative state of
control as well as to how the anal wound heals.
• Excellent results with respect to continence have been reported
with the use of the advancement fl ap although recent reports
have observed disturbances in continence in 9–35%.
a
b
c
d
13. Benign Anorectal: Abscess and Fistula 301
Table 13.4. Results of staged fi stulotomy using a seton.
Author Year Recurrence (%) Incontinence (%)
Ramanujam et al. 1983 1/45 (2) 1/45 (2)
Fasth et al. 1990 0/7 (0) 0/7 (0)
Williams et al. 1991 2/28 (8) 1/24 (4)
Pearl et al. 1993 3/116 (3) 5/116 (5)
Van Tets 1994 – 15/29 (54)
Graf et al. 1995 2/25 (8) 11/25 (44)
Garcia-Aguilar et al. 1996 6/63 (9) 39/61 (64)
Hasegawa et al. 2000 8/32 (25) 15/32 (4.8)
Recurrence
• Recurrence rates after fi stulotomy range from 0 to 18%.
• Causes include failure to identify a primary opening or recognize lateral or upward extensions of a fi stula.
• Premature closure of the fi stulotomy 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.
• Although recurrence rates after anorectal advancement fl aps
were initially reported to be low, with long-term follow-up,
recurrence rates of 40% have been reported.
• Early postoperative complications that have been reported
after fi stula surgery include urinary retention, hemorrhage,
fecal impaction, and thrombosed external hemorrhoids, which
were found to occur in less than 6% of cases.
• With attention to both operative detail and postoperative
follow-up, these complications can be reduced to a minimum.
Special Considerations
Crohn’s Disease
• Anal fi stulas are the most diffi cult and challenging complication of Crohn’s disease to manage.
• They constitute the most common perianal manifestations,
occurring in 6–34% of patients.
• Patients with colonic Crohn’s have a higher incidence with the
rate approaching 100% in those with rectal Crohn’s.
• Delineation of the fi stulous tract is especially important in Crohn’s
disease because many fi stulas may be complex in nature.
302 The ASCRS Manual of Colon and Rectal Surgery
• MRI has been found to detect abscesses that were clinically unsuspected on clinical examination and has been helpful in determining
the relationship of the fi stulous tract to the sphincter muscles.
• Therapeutic goals in managing anorectal fi stulas in Crohn’s disease
remain the alleviation of symptoms and preservation of continence.
Surgical treatment of fi stulas is associated with poor and delayed
wound healing and with the risk of sphincter injury.
• “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 fi stulas
have been reported to heal spontaneously without any surgical
intervention.
• Medications used in the treatment of fi stulas include antibiotics
such as metronidazole and ciprofl oxacin and immunomodulators such as corticosteroids, 6MP, azathioprine, and infl iximab.
• Although several studies have reported spontaneous closure
of fi stulas in 34–50% of patients treated with metronidazole,
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 effi cacious in
only one-third of patients with fi stulizing perianal disease.
• The use of infl iximab has been associated with a 62% reduction in draining fi stulas. The combination of infl iximab and
6MP may prolong the effect of initial infl iximab treatment on
fi stula closure.
• Although fi stulas may occur in as many as 73% of patients
after previous abscess drainage, it is imperative that primary
fi stulotomy not be performed because of the high risk of creating false passages and injuring the sphincter mechanism.
• Low fi stulas with simple tracts can be managed with the standard lay-open method in the absence of active proctitis.
• Fistulotomy has been associated with prolonged healing. Factors associated with delayed healing are rectal involvement,
anorectal complications (especially strictures), and the presence or absence of an internal opening.
• Incontinence has been reported in patients with proctitis who
have not undergone anal surgery. A patient with severe rectal
involvement and even a simple low fi stula is not a candidate for
fi stulotomy. 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.
13. Benign Anorectal: Abscess and Fistula 303
• The results with the use of fi brin glue have been disappointing
with high recurrence rates reported.
• Results with the fi stula plug have been equally disappointing.
This is, however, an attractive alternative which avoids sphincter
muscle division and probably should be tried initially since failure
does not preclude performance of other procedures in the future.
• It is thought that diarrhea from either associated intestinal
involvement or multiple previous small bowel resections is
important in control disorders in these patients. Appropriate
medical therapy should be used to control the diarrhea.
• The importance of quiescent intestinal disease for successful
outcome of local fi stula surgery has been suggested but not
generally accepted and practical.
• A covering stoma may be benefi cial in the patient who has
undergone multiple unsuccessful repairs.
Fistula-in-Ano in the HIV-Positive Patient
• Anal fi stulas are prevalent in the anoreceptive HIV-positive
individual.
• Although anal fi stulas in HIV-positive patients arise from the
dentate line similar to those in HIV-negative patients, they are
more likely to have incomplete anal fi stulas leading to blind
sinus tracts.
• 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 mortality.
• Severity of illness must be assessed before operative intervention because patients with more advanced disease are less
likely to heal their wounds. Data are confl icting as to whether
preoperative CD4+ lymphocyte counts can be related to poor
wound healing; 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.
• 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.
304 The ASCRS Manual of Colon and Rectal Surgery
• In patients who are good operative risks, fi stulotomy is appropriate in patients with intersphincteric or low transsphincteric
fi stulas.
D. Rectourethral Fistulas
Pathophysiology
• Rectourethral fi stulas 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 fi stulization
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.
Investigations
• Prostate-specifi c 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 will show the fi stula 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.
13. Benign Anorectal: Abscess and Fistula 305
Operative Treatment
• Operative repair of rectourethral fi stulas is challenging because
of technical diffi culties that are often encountered as a result of
diffi cult exposure. Multiple repairs have been developed but
there is no consensus as to which is best. Traditionally, it has
been suggested that the fi rst attempt at repair is the best and
that subsequent repairs become more diffi cult.
• Treatment consisting of fecal diversion with either colostomy
or ileostomy and urinary diversion with suprapubic catheterization under cover of antibiotics has been described in the management of rectourethral fi stulas secondary to radiation when
the urethral defect has been found to be too large to repair. This
has been associated with bouts of recurrent sepsis and persistent
symptoms.
Transabdominal Approach
• The transabdominal approach combines the use of abdominoanal pullthrough in combination with omental interposition.
Perineal Approach
• Perineal approaches using the gracilis muscle, dartos, or Martius
fl ap have been described.
Anterior Trans-Anorectal Approach
• In this approach, a midline perineal incision is deepened by
incising all structures superfi cial to the prostatic capsule which
include the superfi cial perineal fascia, the central tendon of
the perineum, and the internal and external sphincters. This
approach allows better access in the repair of complicated
membranoprostatic fi stulas with preservation of continence
and erectile function.
Per-Anal Approach
• This approach has the theoretical advantages of minimal scarring and fewer wound infections although it suffers from limited exposure.
• It involves the use of a full-thickness advancement of anterior
rectal wall protected by diverting colostomy.
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