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Hello, I’m Dr. David Schwartz and welcome to IBDIQ, part of The IBD Project by Takeda, where we’re coming together to help enhance expertise in IBD care—right from the start.
Today, we are going to talk about perianal manifestations of Crohn's disease (or CD). Among patients with inflammatory bowel disease (or IBD), perianal complications are more commonly seen in patients with Crohn’s disease.1 They are less common among those with ulcerative colitis (or UC), where the inflammation is limited to the mucosa.1,2
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We will start by looking at the diverse manifestations of perianal Crohn’s disease but then narrow our focus to perianal fistulas in patients with Crohn’s disease. We’ll discuss current systems for classifying perianal fistulas, such as the Parks classification and the American Gastroenterological Association (or AGA) classification systems. We'll look at a meta-analysis on the prevalence and risk factors of perianal Crohn’s disease. Then, we'll review approaches to the diagnosis. We'll also discuss TOpCLASS, a system that may help guide individual treatment plans for your patients. Finally, we'll review current medical and surgical management approaches and adjuvant therapies for perianal CD.
Perianal CD can range from mild to severe forms of the disease, with diverse manifestations.3-5
Internal or external hemorrhoids are outgrowths of anal mucosa from the rectal wall due to swollen veins.4-6
Anal fissures are tears or splits in the anal canal.4 These fissures can be acute or chronic. Chronic fissures are defined as persisting for 6 weeks or more.
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Skin tags are another potential manifestation.4 Skin tags in perianal CD are typically large, fluid-filled, and hard.
Anorectal strictures arise from the consequence of chronic inflammation in the anal canal or rectum and may be membranous or fibrous.4,5 Strictures can be asymptomatic or can manifest with symptoms such as urgency and difficulty with evacuation.4
A perianal abscess, which is a collection of pus, is a common manifestation of perianal Crohn’s disease and may require surgical intervention.4,7 A perianal abscess often leads to a perianal fistula.4 Clinical manifestations of perianal abscess include tenderness, pain, and fluctuation.4,5
Perianal fistula is the most common manifestation of perianal Crohn’s disease.8 Fistula is defined as an abnormal channel between 2 surfaces, such as the skin and the anus or the rectum.4 Symptoms of a fistula include pain, swelling, and discharge, and the fistula tract may be seen on examination.4,5 The classification of anal fistula is important for understanding fistulizing Crohn’s disease and its management.
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There are several systems used to classify fistulas. Let’s first look at the Parks classification, which is the most established.4,9 This approach was developed based on an anatomical analysis of 400 patients with anal fistulas and remains widely accepted.9,10 Within this system, perianal fistulas are classified into 4 main groups based on the relationship of the fistula tracts to the anal sphincter muscles.9
The first type, intersphincteric fistulas, are fistula tracts located in the space between the external and internal anal sphincter muscles.9
The second type is called transsphincteric fistula. This type crosses both the internal and external sphincter muscles.9
The third type of fistula is the suprasphincteric fistula. Suprasphincteric fistula tracts pass through the internal sphincter and around the external sphincter before exiting to the skin.9,11
And lastly, the fourth type is the extrasphincteric fistula tracts. These fistulas pass from the skin through to the rectum, altogether outside of the external sphincter complex.9
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Let’s now look at a different, more simplified approach to fistula classification.4 The AGA classifies fistulas as either simple or complex.12
According to the AGA system, a fistula is considered a simple fistula when the internal opening is located near the lower regions of the external sphincter muscles and there is a single external opening.12,13
According to the AGA system, complex fistulas are high (have an internal opening located near the deep part of the external sphincter muscles) and can have multiple external openings.12,13 They are also associated with factors such as perianal abscesses, rectovaginal fistulas, anorectal strictures, or active rectal disease.12
At this point you may be wondering, “How prevalent is perianal Crohn’s disease?” Results from a systematic review with meta-analysis of 12 population-based cohort studies from multiple countries may help us understand.14
This study investigated the overall and cumulative 1-, 5-, and 10-year risks of perianal Crohn’s disease (specifically fistulizing disease with or without abscesses) in approximately 24,000 adult and pediatric patients diagnosed with CD between 1970 and 2016.14 This was the first systematic review on the epidemiology and natural history of fistulizing CD based on population-based cohorts.
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In this study, the estimated overall prevalence of perianal fistulizing Crohn’s disease was 18.7%.14
These investigators also looked at the risk of fistulizing Crohn’s disease.14 Approximately 11.5% of patients had fistulizing Crohn’s disease at or before diagnosis. The cumulative risk of fistulizing Crohn’s disease at 1, 5, and 10 years after their diagnosis was found to be 14.3%, 17.6%, and 18.9%, respectively.
Additionally, this systematic review with meta-analysis reported factors that were associated with an increased risk for fistulizing Crohn’s disease.14 Risk factors included colonic disease location, male sex, rectal involvement, and younger age at diagnosis (which was not defined in the meta-analysis).
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Next, let’s discuss approaches to diagnosis and assessment of perianal fistulizing Crohn’s disease. We’ll highlight key recommendations from several organizations, including the American Society of Colon and Rectal Surgeons (or ASCRS), the American College of Gastroenterology (or ACG), and the World Congress of Gastroenterology (or WCOG).15-17
Several approaches are available, including clinical evaluation, endoscopy, examination under anesthesia (or EUA), magnetic resonance imaging (or MRI), endoscopic ultrasonography (or EUS), and transperineal ultrasound (or TPUS).15-17 Note that each of these modalities is addressed with varying degrees of focus in the guidelines. We’ll address each of these as we examine them in more detail.
According to multiple guidelines, initial evaluation of perianal fistulizing Crohn’s disease is through clinical examination.15,17 This can include a thorough medical history in addition to physical examination of the perianal area to assess the presenting symptoms.15
[07:00]
According to the World Congress guidelines, endoscopic assessment of the rectum should be done in addition to a physical examination.17 This can be performed under anesthesia and is useful to identify the extent of the inflammation, internal openings, and other perianal complications.
EUA also has an important role in the evaluation of perianal Crohn’s disease, according to those guidelines.17 It is particularly useful when an anal abscess is suspected and may allow for immediate therapeutic intervention, such as abscess drainage or seton placement.
According to the ASCRS guidelines, diagnostic imaging may not be necessary for all patients with anorectal abscesses or fistula.15 However, they recommend that imaging be considered for selected patients with anorectal Crohn’s disease, recurrent or complex fistulas, immunosuppression, or occult anorectal abscesses.
They note that several studies support the usefulness of MRI for assessing fistulas.15 An advantage of MRI over computed tomography (or CT) is the ability to identify anorectal abscesses and associated fistula tracts.
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The World Congress guidelines characterize MRI as an optional diagnostic method, to be considered if perianal abscess is suspected, and if MRI is readily available.17 As for the ACG guidelines, they recommend cross-sectional imaging with MRI of the pelvis to further characterize perianal Crohn’s disease and perirectal abscesses.16
EUS is an alternative to MRI and may also be used for diagnosis and further characterization of perianal Crohn’s disease and abscess, according to the ACG.16
Both ASCRS and the World Congress guidelines also support endoscopic ultrasonography as an alternative to MRI for assessing perianal abscesses and/or fistulas.15,17 Choice of ultrasonography or MRI depends on availability, expertise, and the complexity of the perianal Crohn’s disease.
Lastly, TPUS is a noninvasive alternative to endoscopic ultrasonography.15 This modality may have accuracy comparable to EUS and may also be considered, according to the ASCRS guidelines.
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These modalities, individually or in combination, may help in identifying and characterizing perianal fistulizing Crohn’s disease, as well as abscesses and implementing proactive management.15,16 The World Congress guidelines actually recommend that modalities be combined to ensure diagnostic accuracy and to determine an optimal management strategy.17 Let’s explore a study that illustrates the potential benefits.
A prospective triple-blinded study evaluated 32 patients between July 1, 1999, and September 1, 2000.18 These patients had Crohn’s disease and suspected perianal fistulas. The study included accuracy assessments of EUA, rectal endoscopic ultrasound (or EUS), and pelvic MRI in determining fistula anatomy.
All 3 methods showed accuracy, which was defined as agreement with a consensus classification from all 3 modalities for greater than or equal to 85% of the patients. 18 EUS and EUA accurately classified 91% of the patients and pelvic MRI accurately classified 87% of the patients.
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Furthermore, combining any 2 of these 3 diagnostic modalities increased accuracy of classifying perianal fistulas to 100%.18
Once perianal fistulizing Crohn’s disease is diagnosed, the Treatment Optimisation and Classification of Perianal Crohn’s Disease classification system (or TOpCLASS for short) can help guide disease management planning.19,20
The TOpCLASS classification system categorizes patients with perianal fistulizing Crohn’s disease based on the severity of their condition and outcomes.20 The TOpCLASS system, was published in 2022, was created as a result of an international consortium. This was composed of perianal Crohn’s disease clinicians and researchers that included gastroenterologists, colorectal surgeons, and gastrointestinal (or GI) radiologists.20,21 The aim of this system is to help patients and their clinicians align on the goals of a tailored disease management strategy.20
There are 4 main classes into which a patient can be categorized according to the TOpCLASS system.20
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Patients with perianal fistulizing Crohn’s disease in Class 1 are those with minimal disease and typically have minimal symptoms related to fistulas and anorectal disease burden.20 Typically, these are patients with inactive or asymptomatic perianal disease and they tend to need minimal intervention over time. For these patients, medical management will focus on establishing a disease management program, preventing disease progression, and promoting healing.
Patients in Class 2 are those with chronic symptomatic perianal fistulas that may need a proactive approach to management.20 This may involve optimizing medical treatments, planned surgical interventions, or a combination of both. Class 2 represents the most common cases encountered and is further divided into 3 subgroups (2a, 2b, and 2c) based on treatment goals, disease impact on quality of life, fistula anatomy, and anorectal disease burden.
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Patients in class 2a are those with symptomatic fistulas suitable for medical and surgical closure.20 Class 2b patients are those with chronic symptomatic fistulas suitable for symptom control. With these patients, the goal is symptom control because either fistula closure is not feasible or because symptom control is the patient’s goal. For patients in Class 2c, who have progressive disease, it is important to recognize that the current therapy alone is not working and if intensive medical and surgical intervention fail to control the disease, a diverting ostomy is recommended. Care should be holistic and should include attention to a patient’s mental health.
Patients who are in Class 3 are those with severe disease and an exhausted perineum or adverse features.20 Severe symptoms may persist despite defunctioning surgery, such as fecal diversion.20,22 This may lead to irreversible destruction of perineal tissue or symptoms significantly limiting quality of life.20 Surgical management, such as proctectomy would likely be needed to restore quality of life in these patients. Still, extensive shared decision-making is called for, as the procedure carries substantial morbidity and involves the necessity of a permanent ostomy.
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Those patients who have undergone a proctectomy and continue to experience perineal lesions are included in Class 4.20 Class 4 is subdivided into 2 groups.
Patients in Class 4a experience a symptomatic sinus or wound suitable for closure or repair, with the goal of sinus closure.20 In contrast, Class 4b patients experience a sinus or wound that is not suitable for surgical repair, or the patient's goal is solely symptom management.
Healthcare providers may use this classification system to assist them in tailoring management strategies and goals to an individual patient, combining medical and surgical approaches on a treat-to-patient-goal basis.20
Guidelines from the ACG and the AGA directly address options for medical management in patients with fistulizing perianal Crohn’s disease.16,23 We’ll focus on the AGA guidelines, which are the most recently published, but supplement with information from the ACG guidelines where appropriate. For variations among the guidelines, please consult the respective publications.
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The AGA guidelines on the medical management of active perianal fistulas provide strong recommendations for using certain anti-tumor necrosis factors (or anti-TNF) therapy over no treatment for inducing and maintaining fistula remission in adult outpatients with Crohn’s disease and active perianal fistula.23 With lower certainty, the AGA guidelines provide conditional recommendation for certain anti-TNF, interleukin inhibitor, or anti-integrin therapy over no treatment for inducing or maintaining fistula remission in these patients.
The AGA guidelines provide a strong recommendation for using biologic agents in combination with an antibiotic over a biologic drug alone for inducing fistula remission in adult outpatients with Crohn’s disease and active fistula without perianal abscess. As a conditional recommendation, the AGA guidelines suggest against using antibiotics alone over no treatment for inducing fistula remission in these patients.
The ACG guidelines suggest that thiopurines may help reduce symptoms of fistulizing Crohn’s disease but note a low level of evidence for this class.16 The AGA Guideline Panel declined to formulate a recommendation based on the limited data available for thiopurines.23
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When medical intervention is not appropriate for a patient with fistulizing perianal Crohn’s disease, surgery may be required.15 The surgical treatment of a fistula is dependent on the patient’s presenting symptoms, the anatomy of the fistula tract, the quality of the surrounding tissues, and previous attempts at fistula repair.
Both the ASCRS and the ACG guidelines recommend that abscesses be treated with prompt incision and surgical or percutaneous drainage.15,16
ASCRS and the AGA guidelines recommend considering the placement of a seton (which is a type of foreign material inserted through a fistula tract that aids in drainage),24 typically in combination with medical treatment.15,16 As noted in the ASCRS guidelines, draining setons are typically used as part of a multimodal approach to managing fistulizing anorectal Crohn’s disease and may be used for long-term disease control.15
The ASCRS guidelines note that symptomatic simple, low anal fistulas in carefully selected patients may be treated by a lay-open fistulotomy.15 This is a surgical technique where fistula tracts are incised and kept open, facilitating early healing.25
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There are also adjuvant therapies, such as fecal diversion and proctectomy, that have been investigated in the treatment of perianal Crohn’s disease.15
The ASCRS guidelines recommend that fecal diversion or proctectomy be considered for patients with uncontrolled symptoms from complex anorectal fistulizing Crohn’s disease.15 These are patients who do not respond adequately to medical therapy, local surgical intervention, or long-term seton drainage. Fecal diversion with or without proctectomy may control anorectal sepsis and improve incontinence symptoms as well as quality of life.
We’ve covered a lot – so let’s take a moment to review the key points discussed today.
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Perianal Crohn’s disease can have diverse manifestations, with perianal fistulas being the most common.4,5,8
The Parks classification system uses an anatomical approach to classifying fistulas, while the AGA classification system is based on a differentiation of simple vs complex.9,12
Diagnosis of perianal fistulizing Crohn’s disease can be made with clinical findings and the use of imaging modalities.15-17 Use of modalities in combination can improve diagnostic accuracy.17
The TOpCLASS classification system categorizes patients with perianal fistulizing Crohn’s disease based on the severity of their condition and outcomes.20
Guidelines are available for both medical and surgical management approaches for perianal fistulizing Crohn’s disease.15,16,23 And finally, fecal diversion and proctectomy can be considered as adjuvant therapies for patients with symptoms not adequately controlled by medical or surgical approaches.15
Thank you for your interest and for spending some time with IBDIQ today to help adapt to the evolving care needs of patients with IBD.
