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Evaluation andManagement
ofAnorectal Abscess
11
Key Concepts
• An abscess around the anus presents with
swelling and redness over the affected area.
• The abscess is named depending on the path
of the anorectal space transversed.
• Drainage is the treatment of choice that should
completely resolve the disease process.
• One should rule out Crohn’s and tuberculosis
while dealing with anorectal abscesses.
11.1 Introduction
Infection in the anal gland is the root cause of
anorectal abscess [1]. It is an acute inammatory
process, while stula is a chronic presentation of
the same disease. Although considered to be of
cryptoglandular origin, conditions like Crohn’s,
HIV, actinomycosis, and tuberculosis may also
be associated with abscesses and subsequent stula formation.
11.2 Epidemiology
An abscess is more frequent in males than in
females [2, 3]. Young males between 30 and
50 years are most affected, with a prevalence of
16.1–20.2 per 100,000 per year [4]. As reported by
some authors, the stula formation rate after an
abscess is 15.5%, while others report an incidence
of 50% [5]. Patients with comorbidities like diabe-
tes, psychological stress, and obesity are more
prone. Other associated risk factors include alcohol intake, smoking, sedentary lifestyle, and
straining at defecation [6].
11.3 Etiology ofAnorectal Abscess
According to cryptoglandular theory, obstruction
in the ducts causes stasis in the anal glands, leading to infection, abscess, or stula formation [7].
Other causes include [8]:
• Tuberculosis
• Actinomycosis
• Crohn’s disease
• Malignancy
• Anal ssure infecting the anal gland
• Pelvic infections resulting from appendicitis,
diverticulitis, and gynecologic sepsis [8]
• Radiation
• As a postoperative complication of episiotomy, hemorrhoidectomy, and closed internal
sphincterotomy
• Immunocompromised patients
• Penetrating injuries like gunshots, stab
wounds, sexual trauma caused by anal sex,
and accidental injuries
• Trauma due to surgeries or ingested chicken
or sh bones. Sometimes ingestion of tooth
pricks may also puncture the rectal wall and
cause an abscess [8]
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2022
K. Gupta, Lasers in Proctology, https://doi.org/10.1007/978-981-19-5825-0_11
141
142
11 Evaluation andManagement ofAnorectal Abscess
11.4 Pathogenesis ofAbscess
Once the anal glands become infected, they fail
to drain through the anal ducts at the dentate line.
Inadequate draining of these glands causes
abscess formation, which extends along a path of
minimal resistance, usually into the intersphincteric, ischiorectal, or supralevator regions [7, 9].
Crohn’s and Tubercular infection may also occur
because of lymphoid follicles surrounding the
anal glands [9].
Some authors believe that stula-in-ano or
abscess results from a congenital abnormality
[10]. Predisposing factors like excess androgens
may lead to infection, thus supporting the congenital theory. However, the cryptoglandular
theory is most widely accepted.
Goligher, in his publication in 1967, stated
that cryptoglandular theory is not applicable in
two-thirds of anorectal infections [11].
11.5 Organisms Responsible
forAbscess
• Escherichia coli
• Bacteroides fragilis
• Klebsiella pneumonia
• Prevotella
• Peptostreptococcus
• Porphyromonas
• Clostridium species
• Fusobacterium
• Streptococcus
• Staphylococcus aureus
11.6 Relation Between Fistulas
andAbscess
Anal stulas and anorectal abscesses are trajectory phases of the same pathogenic process
(Fig.11.1a, b). An anorectal abscess is an acute
inammatory phase, while the anal stulas are
the chronic phase of the same disorder [14]. The
majority of abscesses result from an acute anal
glands infection. A stula is almost always associated with pre-existing anorectal abscess.
The most common organisms responsible for an
abscess include [12, 13]:
11.6 Relation Between Fistulas andAbscess
143
Fig. 11.1 (a, b)
Relation between
abscess and stula
a
b
144
11 Evaluation andManagement ofAnorectal Abscess
11.7 Fate ofAbscess
There can be three outcomes of an abscess. It can
either:
1. Burst and heal on its own
2. Burst and form a stula; or
3. Remain undrained and progress to anal sepsis,
with high morbidity and mortality
11.8 Types ofAbscesses
Different types of abscesses are as follows
(Fig.11.2).
• Perianal (40–60%)
• Ischiorectal (20–25%)
• Intersphincteric (2–5%)
• Supralevator (3.6%)
• Deep postanal (1%)
• Supercial postanal
• Deep anterior anal space abscess
A proper understanding of these abscesses is
essential to distinguish the different stulas.
Fig. 11.2 Types of abscesses
11.9 Pathway oftheSpread ofanAbscess
145
11.9 Pathway oftheSpread
ofanAbscess
The formation of an intersphincteric abscess is an
essential intermediate phase in the evolution of an
anorectal abscess. This intersphincteric abscess
forms around the terminal ramications of the
anal gland in the intersphincteric space [11].
Once a crypt is infected, the infection
spreads along the path of least resistance
(Fig.11.3). It most commonly spreads caudally
into the submucosa due to the direction of anal
glands ramications. A perianal abscess forms
when the abscess extends downward from the
anal sphincter toward the anal margin. An
ischiorectal abscess may result from the spread
of the infection through the external anal
sphincter [11].
A high intermuscular abscess results when the
abscess extends upwards through a plane between
the longitudinal muscles of the anal canal, rectum, and internal anal sphincter. Eisenhammer, in
1958, believed that most abscesses, previously
named “submucosal,” were actually of high intersphincteric type [15].
A cephalad spread of an intersphincteric
abscess toward levators will lead to a supra
levator abscess. The transversalis fascia and the
parietal peritoneum form the upper extent of the
supralevator space. An upward extension of the
abscess through a supralevator space may form
an anterior abdominal wall abscess or rupture
through the peritoneum into the peritoneal cavity
[16].
The internal sphincter helps prevent an intersphincteric abscess from bursting into the rectum
by acting as a barrier [16].
11.9.1 Formation ofaHorseshoe
Abscess andFistula
The typical horseshoe abscess or stula is infralevator inlocation. Most of these originate in the
infected anal gland, at or near the posterior midline on the dentate line [17]. The infection spreads
caudally to deep postanal space from an intersphincteric plane. Since the deep postanal space
communicates with the ischiorectal fossae, an
abscess may spread circumferentially through
this or other intercommunicating spaces leading
to a horseshoe abscess [17] (Fig.11.4). The pus
extends and lies near the levator ani and its external sphincter complex junction. The abscess may
extend anteriorly from a deep anterior anal space
to involve the thigh, the labia, and the scrotum
[17]. In neglected cases, multiple external openings may be present in the perineum.
Fig. 11.3 Pathways of
spread of abscess
146
Fig. 11.4 Horseshoe
abscess
11 Evaluation andManagement ofAnorectal Abscess
11.10 Clinical Evaluation
The symptoms depend upon the site of an
abscess. People suffering from perianal
abscesses complain of swelling and pain. A
patient with an intersphincteric abscess may
present with pain during defecation. Tenesmus,
sepsis, and throbbing lower abdomen pain or
pelvic discomfort are usual symptoms in
patients with supralevator abscess. Fever and
leucocytosis may be present. Due to an extensive ischiorectal space, the patient with an
abscess in this space may not present with any
physical signs at an initial stage. The penetration of Milligan’s septum leads to the appearance of induration or the signs of inammation
over the skin. A bidigital examination may be
helpful for the diagnosis of an ischiorectal
abscess. The abscess above the sensory innervation causes less pain than an acute infralevator
abscess. Urinary retention and paralytic ileus
are signs of an acute illness. On digital rectal
examination, bogginess may be present. An
internal opening is invariably present on proctoscopy, either posteriorly or anteriorly.
11.11 Imaging inAnorectal
Abscesses
Perianal, intersphincteric, and ischioanal
abscesses constitute approximately 86% of infections. It is advisable to use imaging in anorectal
abscesses, deep postanal abscesses, recurrent
abscesses, complex anal stulas, suspicious
occult supralevator abscesses, perianal Crohn’s
disease, and atypical presentations [18]. Endosonography, MRI, or CT scan, are some of the
imaging techniques recommended, according to
the clinical circumstances and available facilities
and resources [18].
11.12 Perianal Abscess
Perianal abscess is the most typical form of an
anorectal abscess. It presents as a tender supercial swelling outside the anal verge [19]. The
incidence reported is 40–60%. Patients with a
perianal abscess may complain of painful swelling that may increase in intensity after defecation
or sitting. Fever and increased leukocyte count
11.12 Perianal Abscess
Fig. 11.5 Perianal
abscess
147
may be the associated ndings. The patient may
present with recurrent swelling at the anal verge,
resolving and reappearing after a few days or
weeks. A communicating intersphincteric stula
tract is usually present (Fig.11.5).
Soft tissue and uncomplicated skin infections
near the anal margin may also cause an abscess
that is not of cryptoglandular origin [20].
Intermuscular and Milligan septum prevent an
abscess from forming a stula as they act as barriers [20].
11.12.1 Dierential Diagnosis
• Hidradenitis suppurativa
• Thrombosed hemorrhoids
• Skin furuncles
• Herpes
• HIV
• Tuberculosis
• Actinomycosis
• Ulcerative colitis
• Bartholin cyst
• Syphilis
If the abscess is associated with multiple ssures, skin tags, or concomitant stula, it may
suggest an underlying Crohn’s disease [19].
11.12.1.1 Diagnosis
Erythema, induration, or uctuance are present
on local examination. On digital examination, the
patient may experience pain and tenderness.
Although proctoscopy becomes challenging to
perform due to the presence of pain, if possible, it
may demonstrate pus oozing out from the base of
the crypt, indicating an internal opening. Digital
rectal examination may reveal bogginess in the
anal region.
11.12.1.2 Managing Perianal Abscess
An abscess may burst by itself or require drainage under local or spinal anesthesia. An incision
is given as near to the anal verge as possible. To
identify any communicating stula tract, do needle aspiration and inject methylene blue and
hydrogen peroxide through the abscess. In the
presence of the dye at the internal opening located
on the dentate line, a primary stulotomy can be
performed if there is no distortion of the anatomy
of the anal sphincters (Fig.11.6a–g).
Drainage of an abscess even in the absence of
uctuation is a must. The pus drained from the
abscess should always be sent for culture as it has
a role in determining the likelihood of subsequent
stula formation. If the culture demonstrates no
bowel-derived organism, the chances of stula
formation are less. If the enteric organisms are
isolated from the culture, there is always a possibility of stula being present. The most typical
organisms isolated are E. coli, Klebsiella pneu-
monia, or Bacteroides species [12, 13].
Perform a primary stulotomy in the presence
of a communicating low intersphincteric stula.
If the pus is oozing out of the internal opening, it
is better to insert a probe from inside and then lay
open the tract. Otherwise, it is better to insert an
artery forceps from the drained abscess site and
148
11 Evaluation andManagement ofAnorectal Abscess
a
b
Fig. 11.6 (a–g) Diagrammatic representation of the
management of perianal abscess. (a) Perianal abscess
with communicating stula tract. (b) Injecting methylene
blue and H2O2 into the abscess cavity after withdrawing
pus. The bubbles at the internal opening indicate a communicating intersphincteric stula tract. (c) Drainage of
abscess from the most medial part of the swelling followed by probing. (d) Primary stulotomy with marsupi-
alization carried out over the probe with excision of
internal opening including mucosa, submucosa, and surrounding tissue to eradicate infection (Park’s technique).
(e) Perianal abscess without communication with the anal
canal. (f) Drainage of pus from the most medial part of the
abscess with a radial incision. (g) Empty abscess cavity
after drainage of pus which collapses over time
11.12 Perianal Abscess
c
d
149
Fig. 11.6 (continued)
e
150
11 Evaluation andManagement ofAnorectal Abscess
f
g
Fig. 11.6 (continued)