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Anorectal Abscess
ZhaominXu andJennyR.Speranza
12
Refer to Algorithm inFig. 12.1
A. The majority of anorectal abscesses result
from cryptoglandular infections. Anal glands
empty into the anal crypts at the level of the
dentate line. Obstruction of the ducts and
glands lead to stasis, bacterial overgrowth,
infection, and ultimately abscess formation.
These abscesses may lead to a resultant stula if there is epithelialization of the draining tract.
B. Approximately 10% of anorectal abscesses
are thought to be associated with some predisposing factors such as Crohn’s disease,
trauma, chronic inammation, immunodeciency, sexually transmitted diseases, malignancy, or foreign bodies. Abscesses are
categorized into four types dependent on
their anatomic positions: perianal, ischiorectal, intersphincteric, and supralevator
(Fig.12.2). The most common types are perianal and ischiorectal. When an abscess
spreads circumferentially through the intersphincteric, deep postanal space, or ischio-
Z. Xu
Department ofSurgery, University ofRochester
Medical Center, Rochester, NY, USA
J. R. Speranza (*)
Division ofColorectal Surgery, Department
ofSurgery, University ofRochester Medical Center,
Rochester, NY, USA
e-mail: jenny_speranza@urmc.rochester.edu
rectal spaces bilaterally, a horseshoe abscess
may result.
C. The most common presenting symptoms are
constant, throbbing acute pain and local
swelling. Perianal abscesses are typically
supercial and may be accompanied by erythema and uctuance overlying the abscess.
Because ischiorectal abscesses arise more
laterally in the ischiorectal space, symptoms
may actually occur on the buttock and anal
margin as opposed to at the anal verge.
Patients with intersphincteric abscesses may
not have any supercial symptoms because
the abscess arises in the intersphincteric
space. Similarly, Patients with supralevator
abscess may also lack visible external signs,
but complain of gluteal pain or pressure. If
spontaneous drainage occurs, then there may
be visible purulent drainage.
D. Any evidence of a systemic infection in the
form of tachycardia, fevers, chills, and leukocytosis or leukopenia should prompt emergent drainage.
E. If possible, a digital rectal examination
should be done, which may demonstrate tenderness or fullness along the rectal wall or
mass. Careful observation may reveal an
external opening suggestive of a stula-inano. Features such as large skin tags or multiple stula openings may suggest an
underlying diagnosis of Crohn’s disease.
© Springer Nature Switzerland AG 2020
S. R. Steele etal. (eds.), Clinical Decision Making in Colorectal Surgery,
https://doi.org/10.1007/978-3-319-65942-8_12
95
96
Z. Xu and J. R. Speranza
Fig. 12.1 Algorithm for anorectal abscess
12 Anorectal Abscess
97
Fig. 12.2 Diagram of the locations of common anorectal abscesses. A: Intersphincteric abscess; B: Ischioanal
abscess. C: Perianal abscess; D: Supralevator abscess.
F. In general, a diagnosis of anorectal abscess is
clinical and does not require further imaging.
For complex abscesses, endoanal ultrasound,
MRI, or CT scan may assist in delineating
the extent of abscesses.
G. The over-riding principal behind the treat-
ment of anorectal abscesses is timely incision and drainage. In the majority of cases,
perianal abscesses can be effectively drained
under local anesthesia in the ofce or at bed
side. After nding the maximal point of tenderness, the area is inltrated with lidocaine. A cruciate or elliptical incision is
made across the overlying skin. Effort
should be made to stay as close to the anus
as possible yet carefully avoiding injury to
the sphincter complex. This will minimize
the length of any subsequent stulas that
may form. In order to decrease the risk of
acute recurrence, the overlying skin can be
excised or a drainage catheter can be placed
within the cavity. An extra step to break up
loculations mechanically can be taken to
With permission from Nicole M. Saur and Dana R.
Sands. Anorectal Abscess. Zutshi M, ed. Anorectal
Disease. Springer Nature 2016
ensure adequate drainage. However, this
should be done with care, especially if the
abscess if very close to the anal sphincter.
Generally, with an adequate incision, postoperative packing is not necessary unless
needed for hemostasis.
H. Large ischiorectal abscesses and horseshoe
abscess may require general anesthesia for
adequate treatment. While small ischiorectal
abscesses can be treated in a similar manner to perianal abscesses with the incision
made as close to the anal verge as possible,
large ischiorectal and horseshoe abscesses
may require an incision over the anococcygeal ligament in the posterior midline
to access the deep postanal space followed
by counter- incisions over the lateral extensions of the abscess overlying the ischiorectal space. This is referred to as a Hanley
procedure. Horseshoe abscesses have a high
rate of recurrence ranging between 18%
and 50% and may require multiple drainage
procedures.
98
Z. Xu and J. R. Speranza
I. An alternative method for large perianal,
ischiorectal and horseshoe abscesses is to leave
a draining mushroom-tip catheter to allow for
adequate drainage and the ability to irrigate
periodically in the postoperative period. A
small incision can be made overlying the
abscess cavity. The cavity is then irrigated and
debrided to break up loculations. The catheter
is then inserted with a probe. Care should be
taken to choose a catheter of an adequate size
so that the catheter will not fall out spontaneously nor be difcult to remove in the ofce.
This will allow irrigation postoperatively if
there is signicant cellulitis and sepsis.
J. Intersphincteric abscesses general require
drainage under anesthesia due to pain.
Drainage should be performed through the
rectum by dividing the internal sphincter
along the length of the abscess.
K. Supralevator abscesses can originate from
different locations, and hence, treatment
should be tailored to where the abscess originates from. A supralevator abscess that originated from an intersphincteric abscess should
be treated transrectally as is done for an
intersphincteric abscess. However, if treating
a supralevator abscess that originated from
an ischiorectal abscess, then drainage should
be performed through the ischiorectal space.
Finally, supralevator abscesses can originate
from a pelvic source secondary to diverticulitis, gynecologic infection or Crohn’s disease.
In these cases, optimal drainage may be
achieved through radiologically guided percutaneous drainage followed by treatment of
the underlying cause.
L. The addition of antibiotics to routine inci-
sion and drainage of an uncomplicated anorectal abscess is generally unnecessary and
has not been shown to reduce healing time
or recurrence rates. Exceptions are patients
that have prosthetic valves, previous bacterial endocarditis, congenital heart disease,
heart transplant patients with valvular
pathology, extensive soft tissue cellulitis,
immunosuppression, diabetes mellitus, or
systemic sepsis. Wound cultures are also
generally not helpful, however, it may be
considered in cases of multiple recurrences
or non-healing wounds.
M. The treatment of abscesses in patients with
Crohn’s disease deserves special care.
Perianal pathology occurs in 40–80% of
Crohn’s patients. Crohn’s patients typically
have a high rate of poor wound healing and
risk of sphincter injury due to chronic inammation leading to large amounts of local
brosis. Management should be focused on
alleviation of perianal sepsis and preservation of continence. Hence, surgical management of anorectal abscesses in these patients
should center around prolonged drainage
with the use of catheters or setons. Medical
management has also been advocated in
Crohn’s patients using antibiotics such as
metronidazole and ciprooxacin to provide
further symptomatic relief.
N. Postoperatively, patients should be instructed
to take ber, non-narcotic analgesia as
needed, and perform sitz baths. Patients may
be re-evaluated in the ofce as soon as
1–2 weeks depending on the complexity of
the procedure and follow up should continue
until complete healing has occurred.
O. Incontinence may occur after the incision
and drainage of an anorectal abscess. This
can result from sepsis and tissue necrosis
secondary to the infection. Baseline continence should be documented prior to any surgical procedure. Iatrogenic damage to the
sphincter complex can occur during the
drainage procedure. Subsequent incontinence can also occur if there is damage to the
puborectalis muscle during the drainage of a
supralevator abscess.
P. Recurrence is more common in those with a
history of abscesses. Recurrence typically
occurs due to incomplete drainage, a missed
abscess in an adjacent space, or an undiagnosed stula. Other reasons for recurrence
that should be entertained if the usual causes
have been ruled out are hidradenitis suppurativa, Crohn’s disease, immunosuppression,
tuberculosis, trauma, and foreign bodies.
Q. Approximately 30–50% of patients with an
anorectal abscess will develop a stula-in-ano.
12 Anorectal Abscess
99
Suggested Reading
Abcarian H. Routine antibiotics for anorectal
abscess: the answer is still no. Dis Colon Rectum.
2011;54(8):917–8.
Mardini HE, Schwartz DA.Treatment of perianal stula
and abscess: Crohn’s and Non-Crohn’s. Curr Treat
Options Gastroenterol. 2007;10(3):211–20.
Rizzo JA, Naig AL, Johnson EK. Anorectal abscess and
stula-in-ano: evidence-based management. Surg Clin
North Am. 2010;90(1):45–68.
Steele SR, Kumar R, Feingold DL, Rafferty JL, Buie
WD.Practice parameters for the management of perianal abscess and stula-in-Ano. Dis Colon Rectum.
2011;54(12):1465–74.
Vasilevsky CA. Anorectal abscess and stula. In: Beck
DE, Roberts PL, Saclarides TJ, Senagore AJ, Stamos
MJ, Wexner SD, editors. The ASCRS textbook of
colon and rectal surgery. 2nd ed. NewYork: Springer;
2011. p.219–44.
Whiteford M.Perianal abscess/stula disease. Clin Colon
Rectal Surg. 2007;20(2):102–9.
Anal Conditions: Fistula-in-Ano
SebastienLachance andMaryliseBoutros
13
Refer to Algorithm in Fig.13.1
A. A stula refers to an abnormal connection
between two epithelial lined surfaces, and in
the case of a stula-in-ano, is characterized
as a tract between the anorectum and perianal skin. Cryptoglandular disease encompasses ~90% of cases, while other etiologies
of anal stula are less common including
postoperative or trauma (3%), inammatory
bowel disease (3%), anal ssure (3%), and
tuberculosis (<1%). In cryptoglandular disease, the stula originates from an infected
anal crypt gland, which is caused by inspissated debris or stool that is blocking the
gland. The anal canal typically consists of
8–10 anal crypt glands at the level of the dentate line. These glands penetrate the internal
sphincter, terminating in the intersphincteric
plane. When a perianal abscess does occur,
pus collects within the crypt and then drains
into the perianal skin through this stulous
tract. Following such an episode, the stula
will fail to heal in 26–38% of cases, thereby
resulting in a chronic stula.
S. Lachance · M. Boutros (*)
Division of Colorectal Surgery,
Jewish General Hospital, Montreal, QC, Canada
e-mail: mboutros@jgh.mcgill.ca
B. The incidence of stula-in-ano is estimated at
2 per 10,000 person-years. This disease presents at a mean age of 40years (range 20–60);
and compared with women, men are twice as
likely to develop an anal stula. Symptoms of
an anal stula are quite variable, and depend
on the location of the external opening and
the complexity of the tract. These may include
discharge (65%), pain (34%), swelling (24%),
bleeding (12%), and diarrhea (5%). If a
patient presents with fever and/or malaise
with pain, cellulitis, or a bulge on the perianal
skin, an anal concomitant abscess should be
suspected. In the context of cryptoglandular
stulas, the stula is usually preceded by a
history of anorectal abscess that drained
spontaneously or by an incision and drainage.
Conversely, severe pain, abdominal cramping, bloating, early satiety, or weight loss
should raise suspicion of underlying Crohn’s
disease or malignancy. Finally, the patient’s
history must be carefully examined for any
symptoms of incontinence, as this may reect
underlying sphincter impairment and will
impact surgical decision-making.
C. Physical examination is essential to deter-
mine the optimal treatment strategy, which
may be conducted in the outpatient clinic setting. However, if the patient experiences discomfort, a thorough examination in the
operating room is always required to accurately plan the denitive management. If
© Springer Nature Switzerland AG 2020
S. R. Steele etal. (eds.), Clinical Decision Making in Colorectal Surgery,
https://doi.org/10.1007/978-3-319-65942-8_13
101
102
S. Lachance and M. Boutros
Fig. 13.1 Algorithm for stula in ano
possible, examination in the outpatient clinic
allows identication of the external opening
of the stula, possible identication of the
internal opening, and performance of a digital
rectal examination to assess sphincter tone
(see section E for a detailed explanation of
the physical examination).
D. Imaging studies are of limited value for most
patients with a rst presentation of uncomplicated stula-in-ano. However, imaging is helpful in select patients with recurrent stulas,
occult abscesses, secondary tract formation, or
Crohn’s disease. Magnetic resonance imaging
(MRI) yields excellent intrinsic soft- tissue
resolution, which can depict the stula tract in
the context of the surrounding structures.
Endoanal ultrasound (EUS) offers a 360° view
of the anal canal, delineating the relationship
of the tract with the anal sphincters and the
internal opening. However, EUS is highly
operator-dependent. MRI is the gold standard
modality with 90% accuracy, whereas EUS
achieves a slightly lower accuracy of 80–89%.
Despite MRI and EUS demonstrating similar
sensitivities (87%), MRI has a higher specicity (69% versus 43%, respectively). In addition
to MRI, a computerized tomography (CT)
scan can be used to evaluate pelvic extensions
of anorectal suppuration—though is not often
useful for stula anatomy. Due to the accuracy
of the aforementioned studies, stulography is
no longer recommended.
E. The goal of the examination in the operating
room is to delineate the relationship of the stula tract with the sphincter muscles and to
appropriately classify the stula according to
the Parks etal. classication (See Fig.15.3), as
this will guide the treatment strategy. It is the
Goodsall’s Rule
a
Anterior: straight tracts
Tr
13 Anal Conditions: Fistula-in-Ano
103
Posterior: curved tracts
ansverse anal line
Fig. 13.3 Illustration of Goodsall’s Rule (Reused with
permission. Feingold DL, Kiely JM.Cannot Find Internal
Fig. 13.2 External opening of a stula. Note the long dis-
tance between the external opening and the internal opening, hinting to the complexity of this suprasphincteric
stula
authors’ preference to perform the physical
examination in the prone jack-knife position.
On inspection, patients may present with an
acute stulous abscess as evidenced by signs of
inammation such as erythema, swelling, and
induration. In the chronic state, the external
opening is seen as a red elevation of granulated
tissue or a pinpoint opening (Fig.13.2). On pal-
pation, purulent or serosanguineous discharge
can usually be elicited. In addition, skin palpation may reveal a cord structure corresponding
to a supercial stula tract. On digital rectal
examination and anoscopy, the internal opening is not always obvious. As stated by
Goodsall’s rule (Fig.13.3), if there is an external opening posterior to the coronal plane, the
internal opening is likely to be found in the dorsal midline; if the external opening is anterior,
the tract has a radial trajectory to the nearest
crypt. As a general rule, the more lateral and
numerous the external openings, the more
complex the stula. When in doubt, probing is
an option that allows identication of primary
openings in the majority of patients. A wide
variety of probes with different sizes, shapes,
and malleability are available (Fig.13.4). This
portion of the examination involves introducing the metallic probe into the external opening
of the stula in order to identify its trajectory,
any side branches, and the internal opening.
Opening of Fistula-in-Ano. In: Lee SW, Steele SR,
Feingold DL, Ross HM, Rivadeneira DE, eds. Colorectal
Surgery Consultation. Tips and Tricks for the Management
of Operative Challenges. Springer Nature, 2019;pp.:111–
113 © Springer Nature)
Probing must be gently conducted with care
taken to avoid creation of a false passage into
the anorectum. If unsuccessful, methylene blue
or dilute hydrogen peroxide can be injected
into the external opening using an olive-tip
metal catheter (Fig.13.5).
F. Simple anal stulas include those classied
by Parks etal. (See Fig.15.3) as intersphincteric or low transsphincteric, and involve less
than 30% of the external sphincter.
F1. Intersphincteric stulas are the most
common, accounting for 31–70% of all
anal stulas. The stula begins at the
dentate line and completes its course at
the anal verge, tracking along the intersphincteric plane. Most intersphincteric
stulas result from a perianal abscess.
F2. Transsphincteric stulas begin at the den-
tate line, tracking up to the perianal skin
overlying the ischiorectal fossa. The tract
encompasses a variable portion of the
internal and external sphincters. Its level
determines how much muscle will be
divided if a stulotomy is elected, and its
potential impact on continence. A low
transsphincteric stula encompasses less
than 30% of the external sphincter.
Transsphincteric stulas comprise between
21% and 53% of anal stulas and are usually preceded by an ischiorectal abscess.
Anus
3 cm
Long anterior fistul
104
Fig. 13.4 Metal
Lockhart-Mummery
stula probes
S. Lachance and M. Boutros
Fig. 13.5 Olive-tipped
metal catheter to be used
for injection into the
external opening
G. Complex stulas comprise roughly 50% of all
stulas, and include high transsphincteric stulas, anterior transsphincteric stulas in females,
any transsphincteric stulas in patients with
impaired continence, extrasphincteric stulas,
and suprasphincteric stulas (Fig.13.2).
G1. High transsphincteric stula tracts fol-
low the same trajectory described in F1,
except that more than 30% of the external sphincter is involved. Anterior transsphincteric stulas in women should be
managed as a complex stula as these
patients have less sphincter muscle bulk
at this location. Likewise, any transsphincteric stula in a patient with
impaired continence should be managed
as a complex stula.
G2. Suprasphincteric stulas start at the den-
tate line and encircle the entire sphincter
complex. The tract traverses over the top
of the puborectalis muscle and through
the levator plate to the ischiorectal fossa
and the overlying skin. The incidence
varies between 2 and 20%.
Too conservative Too aggressive
13 Anal Conditions: Fistula-in-Ano
G3. Extrasphincteric stulas lie outside the
sphincter complex. The tract passes
from the perianal skin to the ischiorectal
fossa and the levator ani, thereafter penetrating the rectal wall. This type of stula should raise suspicion of an etiology
other than cryptoglandular disease
including trauma, inammatory bowel
disease, diverticulitis, or malignancy.
These intra-abdominal etiologies are
best assessed by CT scan. Alternatively,
a transsphincteric stula with a high
blind tract passing through the levator
ani and the rectum is another potential
etiology for an extrasphincteric stula.
Fortunately, this occurs rarely, with an
incidence of 2–3%.
H. Fistula operations can be broadly categorized
as: (1) cutting procedures or non-sphincter
sparing, or (2) sphincter-sparing procedures.
In general, non-sphincter sparing operations
have much better success rates within a
shorter interval of time compared to sphinctersparing procedures. However, non-sphincter
sparing operations require division or destruction of some degree of sphincter muscle making it critical to select the most suitable
patient and stula for these operations
(Fig.13.6).
I. Non sphincter-sparing techniques (Table13.1)
are typically used in the treatment of simple
stulas. One-stage stulotomy is the treatment
of choice and involves opening the stula tract
along its trajectory (Fig.13.7) after successful
probing of the entire tract, and identication of
both the internal and external openings. This
operation has excellent long-term success rates
ranging from 70 to 100%, and a high patient
satisfaction rate up to 87%. Although stulotomy has excellent cure rates, this operation
carries the risk of impaired continence in 15
to 44% of patients, with 30% reporting incontinence to atus, 4% to soft stools, and 2% to
hard stools. Despite a similar recurrence rate,
stulectomy (Fig. 13.7), dened as complete
excision of the stula tract, is not favored
owing to the complexity of the operation and
105
Persistence
Recurrence
Fig. 13.6 Principles of surgical treatment of anal
stulas
Table 13.1 Treatment Options for Fistula-in-Ano
Non Sphincter-Sparing Techniques (I)
Cutting Seton
Fistulotomy
Fistulectomy
Sphincter-Sparing Techniques (J)
Draining Seton
Fibrin Glue
Anal Fistula Plug (Surgisis
Ligation of the Intersphincteric Fistula Tract
(LIFT)
Flaps (Excision and Closure, Mucosal, Skin)
Video-Assisted Anal Fistula Treatment (VAAFT)
Fistula-Tract Laser Closure (FiLaCTM)
Cure
Incontinence
®
Anal Fistula Plug™)
slower healing time. Another non-sphincter
sparing option is the use of a cutting seton.
This procedure requires division of all the
skin and subcutaneous tissue involved in the
stula tract, while a suture is placed within
the tract and snuggly tied around the involved
sphincter muscle. The patient is subsequently
seen every 4–6 weeks to tighten the seton.
The resultant gradual division of the involved
sphincter muscle theoretically allows healing
to occur in a step-wise fashion, thus aiming to
preserve sphincter function. Despite its high
success rate (up to 94%), long-term incontinence rates may still exceed 30%. Thus,
regardless of the technique, any sphincter
division must be undertaken with caution and
knowledge of the patient’s preoperative functional status. When in doubt, it is wise to treat
a simple stula as a complex one.
J. The treatment of complex stulas is chal-
lenging and often may require multiple