This picture shows anterior perianal fistulas
involving the vulva and anterior perineum (arrows) in a woman with Crohn
disease being prepared for surgery. The surrounding skin is
erythematous and indurated. An abscess (arrowhead) appears as a
localized swelling. Hypertrophic skin tags (dashed arrows) in the anal
canal are commonly observed in perianal Crohn disease and may be
confused with external hemorrhoids.
Courtesy of Alain Bitton, MD, FRCPC.
GRAPHICS View All
RELATED TOPICS
Perianal Crohn’s disease
- Authors:
- Alain Bitton, MD, FRCPC
- Alessandro Fichera, MD, FACS, FASCRS
- Section Editor:
- Paul Rutgeerts, MD, PhD, FRCP
- Deputy Editor:
- Kristen M Robson, MD, MBA, FACG
All topics are updated as new evidence becomes available and our peer review process is complete.
Literature review current through: Nov 2019. | This topic last updated: Mar 13, 2019.
INTRODUCTIONCrohn
disease is a chronic inflammatory condition that can affect any part of
the gastrointestinal tract, from the oral cavity to the anus. Perianal
manifestations of Crohn disease include perianal fistula, perianal
abscess, anal canal lesions (anal fissures and anal stricture). Symptoms
can vary from rectal pain and perianal discharge to bleeding or
difficulty with defecation.
This topic will discuss the clinical
features, diagnosis, and management of perianal manifestations of Crohn
disease. The clinical features, diagnosis, and management of luminal
Crohn disease are discussed in detail separately:
●(See "Overview of medical management of high-risk, adult patients with moderate to severe Crohn disease".)
The
diagnosis and management of anal fistula and perianal abscess in
patients who do not have Crohn disease are discussed separately:
NORMAL ANORECTAL ANATOMYThe
following is an overview of the anatomy of the anal region, while a
more detailed description of the anal canal, ischiorectal fossa,
perirectal tissues and sphincteric muscles can be found elsewhere (see "Operative management of anorectal fistulas", section on 'Anatomy of the anal region'):
●The
anal canal, which is surrounded by internal (involuntary) and external
(voluntary) sphincter muscles, extends 2.5 to 3.5 cm to the anal verge
(visible lower edge of sphincter) inferiorly. In the mid-point of the
anal canal is the dentate line, which is the demarcation between
columnar epithelium superiorly and squamous epithelium inferiorly (figure 1).
Along the dentate line lie crypts, which have small glands at their
base. The squamous epithelium between the dentate line and anal verge is
called "anoderm," which is similar to normal skin but highly sensitive,
and the squamous epithelium outside the anal verge is the perianal
skin.
INITIAL EVALUATION OF SYMPTOMSThe
cause of perianal symptoms in patients with Crohn disease is identified
by inspecting the perianal skin and anus, performing digital rectal
examination, and when needed, a more detailed examination under
anesthesia (EUA) (table 1):
●Assess presenting symptoms
– Patients may report local symptoms such as perianal discharge (that
may be purulent or bloody), rectal pain, rectal bleeding, fecal urgency,
difficulty with defecation, or tenesmus. Patients with perirectal
abscess may also present with general symptoms such as fever, chills, or
malaise. Symptoms may be related to more than one perianal condition
(eg, perianal fistula associated with perianal abscess).
●Inspect perianal skin and anus
– Visual inspection of the perianal skin and anus precedes digital
examination. Perianal inspection may reveal visible abnormalities such
as a cutaneous fistula opening (picture 1A-B), external hemorrhoids (picture 2), or anal fissure (picture 3).
For some patients, visual inspection is the extent of the physical exam
because rectal pain precludes palpation of the perianal skin and
digital rectal exam.
●Perform digital rectal examination
– Digital rectal examination (DRE) is preceded by palpation of the
perianal skin if a superficial abscess is suspected. Findings of
perianal erythema and a palpable, often fluctuant, mass or nodule is
suggestive of a superficial perianal abscess.
DRE is performed using topical anesthetic lubricant (eg, 2 percent lidocaine
jelly) if rectal pain is a presenting symptom. The lubricated pad of
the examiner’s finger is then slowly introduced through the anus and
inserted into the rectum with circumferential palpation for any
abnormalities (eg, fluctuance, submucosal fullness, narrowing of anal
canal). Tenderness on digital examination is associated with perianal
abscess, anal fissure, or hemorrhoids. Some patients cannot tolerate
digital rectal examination because of rectal pain due to the underlying
condition (eg, anal fissure, thrombosed hemorrhoid). If digital rectal
examination cannot be performed due to discomfort, this is an indication
for an EUA, which is often followed by radiologic imaging (eg, pelvic
magnetic resonance imaging) to rule out an abscess. (See "Anal fissure: Clinical manifestations, diagnosis, prevention", section on 'Physical examination' and 'Pretreatment evaluation' below.)
PERIANAL FISTULA
Epidemiology — Perianal fistulizing disease affects approximately 5 to 40 percent of patients during the course of their Crohn disease [1-3].
In a population-based study of 169 patients with Crohn disease, 33
patients (20 percent) had at least one perianal fistula during a 25-year
period [1].
Risk factors — Disease
severity, duration, and the presence of distal colonic disease are
associated with a higher prevalence of perianal fistula. Involvement of
the perianal region is more common in patients with colonic disease
compared with those with disease restricted to the small bowel [1,2,4].
In one study, patients with Crohn colitis were greater than three times
more likely to develop perianal fistulas compared with those with
ileitis [5].
Perianal
fistula is the initial manifestation of Crohn disease in approximately
10 percent of patients, however, most patients will develop additional
symptoms (eg, diarrhea, abdominal pain) within one year [2,6]. (See "Clinical manifestations, diagnosis, and prognosis of Crohn’s disease in adults".)
Pathogenesis — In
patients with Crohn disease, fistulas are caused by a penetrating
abscess and/or inflammation into an adjacent organ or the skin. Thus, a
fistula may initially present as an abscess that, upon spontaneous
draining, evolves into a fistulous tract. The fistulous openings most
commonly involve the perianal skin, but can also extend to other sites
(eg, groin, vagina, bladder).
In contrast, an anorectal fistula
that develops in patients without Crohn disease most commonly originate
from an infected anal crypt gland. (See "Anorectal fistula: Clinical manifestations, diagnosis, and management principles", section on 'Etiology'.)
Clinical features
Clinical presentation — Perianal
discharge from a cutaneous opening is a commonly reported symptom, and
the acuity of the presentation often suggests whether or not the fistula
is complicated by an abscess.
●Acute presentation
– Patients with perianal fistula associated with an abscess may present
acutely with rectal pain, perianal tenderness or swelling, and fever.
Purulent discharge from one or more cutaneous opening(s) may be
reported. (See 'Perianal abscess' below.)
●Non-acute presentation
– Patients with a fistula without abscess may complain of nonpurulent
perianal discharge from external opening(s) and may report nonacute
rectal discomfort. Fistulas involving the bladder may be associated with
pneumaturia or fecaluria, and women with fistulas to the vagina may
report a malodorous vaginal discharge. (See "Colovesical fistulas", section on 'Clinical manifestations'.)
On
physical examination, the skin may be erythematous, and a cutaneous
opening may be visible or palpated as induration just below the skin.
The cutaneous opening may be single or multiple, or it may drain fluid
that is bloody, feculent, or purulent (picture 1A-B and picture 4). In some cases, an internal fistula opening can be palpated on digital rectal exam.
Anatomy and classification — Ways of categorizing perianal fistulas include a simple versus complex classification or the Parks classification system (figure 2). The former is more commonly used in clinical practice whereas the latter is used to guide operative management [2,7].
Fistulas can be classified as either simple or complex as follows (see 'Management' below):
●Simple perianal fistula
– A simple fistula is described as a low fistula (confined to the anal
canal), with a single external opening and without abscess or stricture.
This includes superficial fistula and intersphincteric fistula (Parks
type 1).
●Complex perianal fistula
– A complex perianal fistula is described as a high fistula that passes
through or above muscle layers (eg, suprasphincteric fistula, which
includes the entire sphincter apparatus), with single or multiple
external openings, with or without abscess. If the fistula penetrates an
adjacent organ such as the bowel or bladder, it is also considered
complex.
Most simple perianal fistulas respond well to
medical management (ie, antibiotics plus therapy for underlying luminal
Crohn disease [eg, anti-tumor necrosis factor [TNF] agent]). Complex
fistulas typically require a multidisciplinary approach that includes
both medical therapy and surgical intervention. (See 'Management' below.) The Parks classification of perianal fistulas categorizes them into five types based on their relationship to the external anal sphincter and their surgical anatomy (ie, superficial, intersphincteric, transsphincteric, suprasphincteric, extrasphincteric) (figure 2 and figure 3) [8,9]. This classification system describes the anatomic path of the fistula and is most useful for planning operative treatment. (See "Operative management of anorectal fistulas".)
The Parks classification system is discussed in more detail separately (see "Anorectal fistula: Clinical manifestations, diagnosis, and management principles", section on 'Classification').
Diagnosis — The
diagnosis of fistula is based upon characteristic findings on history
and physical examination: cutaneous opening usually with perianal
drainage with or without rectal pain. (See 'Clinical features' above.)
While
imaging studies are not required for diagnosis of simple fistulas, they
are useful for excluding an abscess, defining the fistula tract in
relation to the sphincter complex, and planning treatment for both
simple and complex fistulas. (See 'Pretreatment evaluation' below and "The role of imaging tests in the evaluation of anal abscesses and fistulas".)
Pretreatment evaluation — Therapy
for perianal fistulas can be guided by further evaluation (imaging with
pelvic computed tomography [CT], pelvic magnetic resonance imaging
[MRI] or rectal endoscopic ultrasound [EUS]; rectosigmoid endoscopy;
examination under anesthesia [EUA]) that helps define the fistula
anatomy and exclude the presence of a perianal abscess. (See 'Anatomy and classification' above and "The role of imaging tests in the evaluation of anal abscesses and fistulas".)
The sequence of pretreatment testing depends on the acuity of the clinical presentation:
●Patients
who present acutely with clinical findings suggestive of abscess (eg,
fever, persistent perianal pain, purulent drainage, a palpable,
fluctuant mass) first require prompt referral to a colorectal surgeon
for EUA with abscess drainage and/or seton placement if needed. We also
typically obtain pelvic CT with intravenous contrast only if an abscess
is suspected. (See 'Patients with abscess' below.)
●Patients
without symptoms of an abscess undergo the following non-urgent
pretreatment evaluation to define the fistula tract, exclude occult
abscess, and assess the rectosigmoid colon for active mucosal Crohn
disease (see 'Perianal abscess' below):
•MRI of the pelvis (or rectal endoscopic ultrasound)
– Imaging studies for evaluating perianal fistula (pelvic MRI and
rectal EUS) show air or contrast material within the fistula and help
define the fistula tract (image 1 and image 2 and image 3 and image 4). We generally obtain pelvic MRI because it is noninvasive and preferred for patients who present with perianal pain.
The diagnostic accuracy and use of imaging tests for evaluating perianal fistula are discussed separately. (See "The role of imaging tests in the evaluation of anal abscesses and fistulas".)
•Rectosigmoid endoscopy
– Rectosigmoid endoscopy assesses the rectal mucosa for active Crohn
disease (eg, mucosal erythema, ulceration) and may identify the internal
opening of the fistula. (See "Clinical manifestations, diagnosis, and prognosis of Crohn’s disease in adults", section on 'Endoscopy'.)
While
the external opening of a fistula is usually visualized on the skin,
the internal fistula opening may be seen endoscopically. The internal,
mucosal opening of a low perianal fistula may be viewed with anoscopy,
but sigmoidoscopy may be required to see a more proximal fistula with
the internal opening in the rectum.
•Examination under anesthesia – During
examination under anesthesia, the surgeon drains any sepsis encountered
and probes the fistula tract with the intent of placing a noncutting
seton. EUA is especially important for patients who cannot tolerate
digital rectal examination due to perianal pain. In addition,
rectosigmoid endoscopy is usually performed at the time of EUA. (See 'Management' below.)
Obtaining
at least two studies (EUA and MRI pelvis or rectal EUS) as part of
pretreatment evaluation improves accuracy of determining the anatomy of
the fistula. In a study of 32 patients with perianal Crohn disease,
visualizing the perirectal space with two different modalities (EUS,
MRI, or examination under anesthesia) accurately defined the anatomy for
all fistulas compared to a consensus opinion of the anatomy based on
all diagnostic studies [10].
Management
Goals and sequence of therapy — The following principles guide our approach to management of patients with perianal fistulas:
●Goals of therapy – Complete
fistula closure is the primary therapeutic goal for most patients. For
some patients with complex perianal fistulas, the achievable goal of
therapy is symptomatic improvement (eg, less rectal pain, reduced
drainage) and better quality of life but without complete fistula
healing and closure [11]. (See 'Patients with nonhealing fistula' below.)
●Sequence of therapies – The
general sequence of multidisciplinary interventions is to eradicate the
infection, if present; assess the status of luminal Crohn disease and
the fistula tract in order to initiate medical therapy; and intervene
surgically if needed (eg, nonhealing fistula).
●Preference for therapies
– There is no single preferred treatment strategy for patients with
perianal fistula, and various medical and surgical options are
available. Our preference for therapies depends on the severity of the
patient’s symptoms, the anatomic complexity of the fistulas, the risk of
adverse events, activity of the underlying Crohn disease, and patient
preferences. Much of the data on the treatment of fistulas in Crohn
disease is based upon case series, with few controlled trials.
The
degree of inflammation and distribution of mucosal Crohn disease
factors into overall management. Active inflammation in the rectum
impairs fistula healing, and we optimize medical therapy to heal mucosal
disease and to achieve clinical, endoscopic, and histologic remission.
The approach to treating luminal Crohn disease is discussed separately.
(See "Overview of the medical management of mild (low risk) Crohn disease in adults" and "Overview of medical management of high-risk, adult patients with moderate to severe Crohn disease".)
●Multidisciplinary approach
– Management of perianal fistulas, and complex fistulas in particular,
usually requires input from multiple disciplines (gastroenterology,
colorectal surgery, radiology).
Simple fistula
Patients without symptoms — Patients
with simple fistulas who are asymptomatic may not require treatment. If
a patient with a simple fistula does not complain of rectal pain or
drainage, we generally do not begin specific treatment for the fistula.
We continue to treat the patient's underlying Crohn disease. Many of
these patients will remain asymptomatic or the fistula will
spontaneously heal. In a study including 21 patients with Crohn disease
and perianal fistulas, seven patients (33 percent) remained asymptomatic
despite continued presence of the fistula, while eight patients (38
percent) had spontaneous healing during 10 years of follow-up [12].
Patients with symptoms
Initial therapy — For patients who are symptomatic (eg, rectal pain, perianal drainage), initial therapy consists of oral antibiotic therapy (metronidazole or ciprofloxacin)
in conjunction with treatment of mucosal rectal inflammation due to
underlying Crohn disease. For patients with simple perianal fistula, the
need for anti-TNF agents is determined by the status of the underlying
mucosal disease, which is discussed separately. (See 'Goals and sequence of therapy' above and "Overview of the medical management of mild (low risk) Crohn disease in adults" and "Overview of medical management of high-risk, adult patients with moderate to severe Crohn disease".)
We begin metronidazole 500 mg twice daily and make adjustments based on clinical response and presence of adverse effects [13-16]:
●For patients who respond (ie, with cessation of drainage and closure of the fistula) after four weeks of metronidazole, we decrease the dose to 250 mg three times per day, continue therapy for another four weeks, and then stop it.
●For patients who develop adverse effects with metronidazole 500 mg twice a day, we reduce the dose to 250 mg three times a day (or switch to ciprofloxacin 500 mg twice daily) for a four-week course of therapy [17].
Adverse effects that are commonly associated with metronidazole are
gastrointestinal symptoms (eg, nausea, vomiting, diarrhea, anorexia),
and toxicity of metronidazole is discussed separately. (See "Metronidazole: An overview", section on 'Toxicity'.)
●For patients who do not respond to either metronidazole or ciprofloxacin after four weeks of therapy, options include initiating biologic therapy or surgical intervention. (See 'Drug therapy' below.)
Antibiotics
are associated with reduced fistula drainage, fistula closure, and
symptomatic improvement for patients with perianal Crohn disease,
although data supporting their efficacy are mainly limited to small
trials and studies [14,15,18-20].
The selection and dosing of antibiotic therapy are based on available
data, traditional practice patterns, and clinician preference. Fistula
healing rates with metronidazole
(1000 to 1500 mg daily) range from 0 to 56 percent, while fistula
recurrence after discontinuing antibiotics is not uncommon
(approximately 75 percent of patients in one small study) [14]. In a meta-analysis of three trials including 112 patients with perianal fistula, patients treated with ciprofloxacin
were more likely to have either reduced fistula drainage or closure
compared with placebo (risk ratio 1.64, 95% confidence interval
1.16-2.32) [18].
Ciprofloxacin (500 mg twice daily) was compared with metronidazole (500
mg twice daily) or placebo in a 10-week trial of 25 patients with
perianal Crohn disease [17].
Rates of fistula closure were not significantly different for
ciprofloxacin compared with metronidazole or placebo (30 versus 0 or 13
percent, respectively).
Recurrence after initial response — Some patients will have a fistula recurrence following initial improvement when antibiotics are discontinued [14]. Patients who initially responded to a course of antibiotics (ie, metronidazole or ciprofloxacin) are given a second course of antibiotic therapy for four weeks. (See 'Initial therapy' above.)
Subsequent therapy — For
patients with simple fistulas who do not respond to antibiotic therapy
or who have fistula recurrence after initial healing, medical therapy
with a biologic agent is initiated. (See 'Drug therapy' below.)
Seton
placement is also performed; however, fistulotomy is an alternative
option for patients with a nonhealing, superficial fistula with minimal
sphincter involvement, which rarely occurs. A fistulotomy involves
laying open the fistula tract in its entirety, and healing rates after
fistulotomy for patients with Crohn disease are high in most studies (80
to 100 percent) [7]. The fistulotomy procedure and its efficacy in patients without Crohn disease are discussed separately. (See "Operative management of anorectal fistulas", section on 'Procedures for simple fistulas'.)Patients with simple perianal fistula who do not respond to oral antibiotics and/or EUA with draining seton placement are managed with the treatment approach used for patients with complex perianal fistula. (See 'Complex fistula' below.)
Complex fistula
Patients with abscess — Patients
who have perianal fistula complicated by abscess require prompt
surgical drainage of the abscess that is performed during EUA with
placement of a noncutting silastic seton (a drain that is threaded into
the cutaneous orifice of a fistula, through the fistula tract, and into
the rectum and anal canal) when needed, in addition to antibiotic
therapy. We typically give a two-week course of oral metronidazole 500 mg twice daily (or ciprofloxacin 500 mg twice daily is an alternative) [21] (algorithm 1) (see 'Pretreatment evaluation' above).
The clinical presentation and management of perianal abscess is discussed below. (See 'Perianal abscess' below.)After the abscess is drained and infection is treated, medical therapy with an anti-TNF agent can be initiated, and timing of seton removal is determined as outlined below. (See 'Patients without abscess' below.)
Local sepsis in the pelvis leads to tissue destruction of the anal sphincter, and setons are placed for continuous drainage. The combination of a draining seton followed by therapy with anti-TNF-agent results in higher rates of fistula healing and longer duration of fistula closure compared with anti-TNF agents alone [22-25]. (See 'Drug therapy' below.)
Patients without abscess
Examination under anesthesia — Patients
with complex perianal fistula without abscess require a combined
approach consisting of non-urgent EUA with seton placement and medical
therapy (an anti-TNF-agent combined with antibiotic therapy) [22,23,26]. (See 'Pretreatment evaluation' above and 'Drug therapy' below.)
Timing
for removal of setons relative to ongoing medical therapy is a joint
decision involving the colorectal surgeon and gastroenterologist. After
setons are removed, the degree of fistula closure is assessed clinically
by reduced drainage. Imaging (eg, pelvic MRI, rectal endoscopic
ultrasound) can also determine if the fistula tract remains open or
inflamed [27]. Anti-TNF agents are continued as maintenance therapy for patients with Crohn disease and healed fistulas. (See "Overview
of medical management of high-risk, adult patients with moderate to
severe Crohn disease", section on 'Maintenance therapy'.)If the fistula does not heal despite these measures including dose-optimizing the anti-TNF agent, options include replacement of setons, further surgical intervention as discussed below, or switching to a different biologic agent (eg, vedolizumab). (See 'Patients with nonhealing fistula' below.)
Dosing for anti-TNF agents and therapeutic drug monitoring are discussed separately. (See "Treatment of Crohn disease in adults: Dosing and monitoring of tumor necrosis factor-alpha inhibitors".)
Drug therapy — Initial drug therapy for complex perianal fistula without abscess consists of anti-TNF agent (eg, infliximab, adalimumab) combined with antibiotic therapy. We typically use oral metronidazole 500 mg twice daily (or ciprofloxacin 500 mg twice daily is an alternative) for two weeks.
The
approach to induction and maintenance therapy with anti-TNF agents with
or without an immunomodulator for patients with Crohn disease is
discussed in more detail separately. (See "Overview
of medical management of high-risk, adult patients with moderate to
severe Crohn disease", section on 'Induction therapy' and "Overview
of medical management of high-risk, adult patients with moderate to
severe Crohn disease", section on 'Maintenance therapy'.)Dosing, monitoring and adverse effects of anti-TNF agents are discussed separately:
Anti-TNF agents are effective for healing and closure of perianal fistula, although fistula status was not a primary endpoint for some of the randomized trials which evaluated the efficacy of anti-TNF agents for patients with Crohn disease [28-33]. In a trial of 94 patients with Crohn disease and perianal fistula, induction therapy with infliximab (5 mg/kg or 10 mg/kg) was associated with higher rates of complete fistula closure compared with placebo (55 or 38 percent, respectively, versus 13 percent) [28]. In a 54-week maintenance trial of 282 patients with fistulizing Crohn disease, patients given infliximab 5 mg/kg every eight weeks had higher rates of fistula closure compared with placebo (36 versus 19 percent) [29].
Combination of an anti-TNF agent with ciprofloxacin may offer more benefit compared with anti-TNF monotherapy [17,34,35]. In a trial of 76 patients with fistulizing Crohn disease, adalimumab combined with ciprofloxacin resulted in higher rates of clinical response (defined as a 50 percent reduction of fistula at 12 weeks) compared with adalimumab plus placebo (71 versus 47 percent) [35].
Maintenance therapy with infliximab appears to reduce the need for surgery or inpatient hospitalizations. In a trial of 195 patients with fistulizing Crohn disease who initially responded to infliximab therapy and were evaluated at week 54, infliximab (5 mg/kg every eight weeks) was associated with fewer inpatient hospitalization days (0.5 versus 2.5 days) and fewer surgeries and procedures (65 versus 126 procedures) compared with placebo [36].
Biologic agents are preferred for long-term treatment of perianal fistula; however, thiopurines (azathioprine [AZA] and 6-mercaptopurine [6-MP]) may be beneficial when used either as an alternative therapy for patients who cannot tolerate or do not wish to start an anti-TNF agent, or as part of combination therapy with an anti-TNF agent [37]. A meta-analysis of five randomized controlled trials showed that AZA or 6-MP treatment resulted in higher rates of complete fistula healing or decreased discharge (54 versus 21 percent) [38]. (See "Overview of medical management of high-risk, adult patients with moderate to severe Crohn disease", section on 'Thiopurines' and "Overview of medical management of high-risk, adult patients with moderate to severe Crohn disease", section on 'Combination therapy'.)
Vedolizumab, an alpha-4-beta-7 integrin monoclonal antibody, shows promise for treatment of perianal fistula. In a subgroup analysis of a larger clinical trial [39], vedolizumab resulted in some benefit for patients with fistulizing Crohn disease [40]. There is no definitive data showing benefit of ustekinumab for patients with perianal fistula.
Patients with nonhealing fistula — For
patients who have failed medical management (defined as persistent
drainage with a visible external opening and an associated tract on
imaging), surgical interventions beyond seton placement can result in
long-term improvement [41].
The goals of surgery are to close the fistula while preserving fecal
continence or to reduce symptoms by making management easier for the
patient such as by transforming a complex fistula into one closer to the
anus which is controllable by a small pad.
Surgical planning includes the following:
●Timing of intervention
– The timing of surgery depends on whether or not active inflammation
in the distal rectum and anal canal is present. Patients with active
proctitis are treated medically before surgical intervention for
persistently draining fistula, because surgical outcomes are better when
luminal disease is in remission [42]. (See "Overview
of medical management of high-risk, adult patients with moderate to
severe Crohn disease", section on 'Induction therapy'.)
●Choosing an intervention
– The choice of intervention depends on several factors such as the
location, type, and duration of the fistulizing disease. Surgical
options include: removal of the seton with or without an advancement
flap (rectal or cutaneous); simple fistulotomy (provided that the
fistula is subcutaneous); ligation of the intersphincteric tract (ie,
LIFT procedure); or proctectomy with permanent fecal diversion
(particularly for patients with debilitating fecal incontinence) [41,43]. These surgical approaches are described separately. (See "Operative management of anorectal fistulas".)
The
local injection of mesenchymal stem cells is a promising therapy for
nonhealing perianal fistula. In a trial of 212 patients with Crohn
disease and nonhealing complex fistulas, an injection of adipose-derived
stem cells resulted in higher rates of fistula closure at one year
compared with placebo (56 versus 39 percent) [44].
Prognosis — For
most patients with perianal fistula and Crohn disease, a
multidisciplinary approach with medical therapy with an anti-TNF agent
combined with surgical intervention is successful in alleviating
symptoms, reducing fistula drainage, and healing fistulas. Therapy with
anti-TNF agents results in maintenance of remission for both luminal and
fistulizing Crohn disease [29,31-33,45], however, the risk of fistula recurrence in the era of biologic therapy is not well defined. (See "Overview
of medical management of high-risk, adult patients with moderate to
severe Crohn disease", section on 'Maintenance therapy'.)
Carcinoma (squamous or adenocarcinoma) can rarely develop within the perianal fistulous tract [46,47].
Carcinoma should be suspected in patients who have chronic, nonhealing
fistulas containing copious granulation tissue and induration. In such
patients, examination under general anesthesia with biopsy and curettage
of the fistula tract is performed. If cancer is found, management is
similar to that for patients with anal or colorectal malignancies. (See "Overview of the management of rectal adenocarcinoma" and "Clinical features, staging, and treatment of anal cancer".)
PERIANAL ABSCESSPerianal
abscess should be suspected in patients who present with constant pain
in the anal or rectal area, fever or purulent discharge. Purulent rectal
discharge may be noted if the abscess has begun to drain spontaneously
or if it is associated with a perianal fistula. A perianal abscess in a
patient with Crohn disease is often related to obstruction of a perianal
fistula tract but may also originate from an infected anal crypt gland (figure 4).
A
superficial anorectal abscess can be diagnosed on physical examination
with findings of perianal erythema and a palpable, often fluctuant mass (picture 1A, 1C).
A deeper abscess can be diagnosed by feeling a tender, often fluctuant
mass internally on digital rectal exam, or by imaging studies, such as
pelvic magnetic resonance imaging or ultrasound of the pelvis. The
classification and clinical features of perianal abscess are discussed
separately. (See "Perianal and perirectal abscess", section on 'Classification' and "Perianal and perirectal abscess", section on 'Clinical manifestations' and "Perianal and perirectal abscess", section on 'Diagnosis'.)Treatment of perianal abscess in patients with Crohn disease includes prompt surgical drainage, seton placement for continued drainage (if the tract is identified), and a short course (ie, two weeks) of antibiotics (usually metronidazole or ciprofloxacin) [17,48]. If the perianal abscess is associated with a perianal fistula, medical management (anti-tumor necrosis factor agent) for fistulizing Crohn disease is started after the local infection is controlled and the abscess has been drained. (See 'Complex fistula' above.)
The medical and surgical management of perianal abscess and descriptions of the surgical interventions are discussed in more detail, separately. (See "Perianal and perirectal abscess", section on 'Management'.)
ANAL FISSURES
Clinical features and diagnosis — An anal fissure is an ulcer in the lining of the anal canal distal to the dentate line (picture 3).
Anal fissures in patients with Crohn disease are secondary to
ulceration from underlying mucosal inflammation, in contrast to sporadic
anal fissures, which are associated with increased internal anal
sphincter pressure [49]. (See "Anal fissure: Clinical manifestations, diagnosis, prevention", section on 'Pathogenesis'.)
Anal fissures in Crohn disease may be asymptomatic or present with bleeding, deep ulceration (picture 5),
or anal pain, which may be worse with defecation. Characteristics of
anal fissures in patients with Crohn disease include location other than
the posterior midline (eg, lateral or anterior) and multiple,
recurrent, or nonhealing fissures. In addition, hypertrophic, edematous
skin tags may be present and may show granulomas if biopsied (picture 1A-B) [50]. (See "Clinical manifestations, diagnosis, and prognosis of Crohn’s disease in adults", section on 'Endoscopy'.)The diagnosis of anal fissure is suspected based upon clinical presentation and is confirmed with physical examination by either directly visualizing a fissure or reproducing the patient's presenting complaints (ie, anal pain) by gentle digital palpation of the anal verge. Clinical features of anal fissure and performing physical examination to confirm the diagnosis are discussed in more detail separately. (See "Anal fissure: Clinical manifestations, diagnosis, prevention", section on 'Clinical manifestations' and "Anal fissure: Clinical manifestations, diagnosis, prevention", section on 'Diagnosis'.)
Treatment
●Initial therapy
– Initial therapy for anal fissures in patients with Crohn disease is
similar to that in the general population, and the goals of therapy are
both fissure healing and improving symptoms. Medical management includes
supportive measures (warm sitz baths, topic analgesics such as lidocaine jelly) and a topical vasodilator (nifedipine or nitroglycerin).
The anoderm should be kept clean and dry, but without excessive wiping
or use of astringent cleaners. Initial therapy for anal fissures is
discussed in more detail separately (see "Anal fissure: Medical management").
●Subsequent therapy
– Fissures that do not heal despite supportive measures and topical
therapy with vasodilators and calcium channel blockers may require
additional therapy. In some patients, a nonhealing ulcer in the
posterior midline of the anal canal may appear as a typical anal
fissure; however, the ulcer is often related to underlying active
inflammation from Crohn disease and should be treated with medical
therapy, rather than an intervention that will decrease anal sphincter
tone and increase the risk of incontinence. Lateral internal
sphincterotomy is not performed due to the risks of injuring the
sphincter mechanism, fecal incontinence, and poor wound healing. In
addition, surgery should be avoided in patients with active proctitis as
it predisposes to poor healing [51]. (See "Anal fissure: Surgical management".)
OTHER PERIANAL DISEASES
Anal stricture — Chronic mucosal inflammation associated with anorectal Crohn disease may lead to fibrosis and subsequently to anal stricture [52].
Symptoms suggestive of anal stricture include fecal urgency or
frequency, and tenesmus or difficulty with defecation, although some
patients may not report any symptoms and the stricture is seen
incidentally at the time of endoscopy [7].
The evaluation of an anal stricture includes endoscopy with biopsies to
determine if the stricture is inflammatory, fibrotic, or dysplastic,
and examination under anesthesia with biopsies and pelvic magnetic
resonance imaging are subsequently performed for some patients (eg,
those with nondiagnostic endoscopic findings) [42].
A
symptomatic, short fibrotic anal stricture without surrounding mucosal
inflammation is managed with endoscopic balloon dilation or with
dilation during examination under anesthesia (EUA), while inflammatory
strictures are treated with medical therapy for luminal Crohn disease
(eg, anti-TNF agent which is discussed separately) with or without
mechanical dilation. (See "Overview
of medical management of high-risk, adult patients with moderate to
severe Crohn disease", section on 'Induction therapy'.)Patients with an anorectal stricture that cannot be traversed with the endoscope should be referred for surgical consultation for EUA, stricture dilation, and consideration of resection. (See "Surveillance and management of dysplasia in patients with inflammatory bowel disease", section on 'Strictures'.)
Hemorrhoids — Patients
with Crohn disease may develop hemorrhoids, which are not related to
their underlying Crohn disease. Patients with hemorrhoids commonly
present with rectal bleeding, especially with bowel movements, or a
sensation of rectal fullness. Therapy for hemorrhoids is local and
conservative (ie, dietary and lifestyle modification, topical
analgesics, and topical glucocorticoids), and this is discussed
separately. (See "Home and office treatment of symptomatic hemorrhoids".)
Patients
who have persistent symptoms despite initial therapy are referred to a
colorectal specialist for consideration of treatment. Hemorrhoidectomy
should be avoided because of the possibility of poor wound-healing and
of damaging the anal sphincter.
SOCIETY GUIDELINE LINKSLinks
to society and government-sponsored guidelines from selected countries
and regions around the world are provided separately. (See "Society guideline links: Crohn disease in adults" and "Society guideline links: Anal abscess and anal fistula".)
INFORMATION FOR PATIENTSUpToDate
offers two types of patient education materials, "The Basics" and
"Beyond the Basics." The Basics patient education pieces are written in
plain language, at the 5th to 6th grade reading
level, and they answer the four or five key questions a patient might
have about a given condition. These articles are best for patients who
want a general overview and who prefer short, easy-to-read materials.
Beyond the Basics patient education pieces are longer, more
sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here
are the patient education articles that are relevant to this topic. We
encourage you to print or e-mail these topics to your patients. (You can
also locate patient education articles on a variety of subjects by
searching on "patient info" and the keyword(s) of interest.)
●Basics topics (see "Patient education: Crohn disease in adults (The Basics)")
●Beyond the Basics topics (see "Patient education: Crohn disease (Beyond the Basics)" and "Patient education: Anal fissure (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Perianal
manifestations of Crohn disease include perianal fistula, perianal
abscess, and anal canal lesions (anal fissures and anal stricture).
Symptoms can vary from rectal pain and perianal discharge to bleeding or
difficulty with defecation. (See 'Introduction' above.)
●For
patients with Crohn disease, the cause of perianal symptoms is
identified by inspecting the perianal skin and anus, performing digital
rectal examination, and when needed, a more detailed examination under
anesthesia (table 1). (See 'Initial evaluation of symptoms' above.)
●For
patients with Crohn disease, fistulas are caused by a penetrating
abscess and/or inflammation into an adjacent organ or the skin. The
fistulous openings most commonly involve the perianal skin, but can also
extend to other sites (eg, groin, vagina, bladder). (See 'Pathogenesis' above.)
●For
patients with Crohn disease, diagnosis of a perianal fistula is based
upon characteristic findings on history and physical examination: a
cutaneous opening usually with perianal drainage with or without rectal
pain. While imaging studies are not required for diagnosis of simple
fistulas, they are useful for excluding an abscess, defining the fistula
tract, and planning treatment. (See 'Diagnosis' above and "The role of imaging tests in the evaluation of anal abscesses and fistulas".)
●For
most patients with Crohn disease and perianal fistula, complete fistula
closure is the primary therapeutic goal. For some patients with complex
perianal fistulas, the achievable goal of therapy is symptomatic
improvement (eg, less rectal pain, reduced drainage) and better quality
of life but without complete fistula healing and closure. (See 'Goals and sequence of therapy' above.)
●For
patients with simple fistula who are asymptomatic, we generally do not
begin specific treatment for the fistula, while we continue to treat
underlying Crohn disease. (See 'Patients without symptoms' above.)
●For
patients with Crohn disease and perianal fistula who are symptomatic
(eg, rectal pain, perianal drainage), we suggest antibiotic therapy in
addition to treatment for underlying Crohn disease rather than no
antibiotic therapy (Grade 2C). For patients with simple fistula, we typically use oral metronidazole 500 mg twice daily for four weeks and make dosing adjustments based on clinical response and patient tolerance. (See 'Initial therapy' above.)
For
patients with complex perianal fistula, examination under anesthesia is
first performed for abscess drainage and seton placement (if needed).
We typically use oral metronidazole 500 mg twice daily (or ciprofloxacin 500 mg twice daily) for two weeks in addition to anti-tumor necrosis factor (TNF) therapy (algorithm 1) (see 'Complex fistula' above and "Overview
of medical management of high-risk, adult patients with moderate to
severe Crohn disease", section on 'Induction therapy').
●For
patients with perianal fistulizing Crohn disease who respond to
induction therapy with an anti-TNF agent, we suggest continued
maintenance with the anti-TNF agent (Grade 2B). (See 'Drug therapy' above.)
●For
patients with Crohn disease and perianal abscess, treatment includes
prompt surgical drainage, seton placement for continued drainage (if the
tract is identified), and a course of antibiotic therapy (typically metronidazole or ciprofloxacin). (See 'Perianal abscess' above and "Perianal and perirectal abscess".)
●For
patients with Crohn disease and anal fissure, therapy includes
supportive measures (warm sitz baths, topic analgesics such as lidocaine jelly) and a topical vasodilator (nifedipine or nitroglycerin). Surgery should be avoided in patients with active proctitis as it predisposes to poor healing. (See 'Treatment' above and "Anal fissure: Medical management".)
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