In a patient presenting with suspected inflammatory bowel disease, the initial endoscopic evaluation is a valuable tool for determining the correct disease diagnosis and the extent and severity of disease. A full colonoscopy and ileoscopy should be performed when possible, with systematic biopsies from each segment. When a diagnosis of inflammatory bowel disease is established, it is possible to distinguish between Crohn disease and ulcerative colitis, and specific endoscopic features may assist in this categorization. Because patchy healing can occur with treatment, it is important to obtain a thorough and accurate assessment of disease characteristics and distribution before initiating therapy.
Key points
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The initial colonoscopy in IBD should include a careful perianal inspection and digital rectal examination, to assess for findings associated with perianal Crohn’s disease.
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It is important to perform a thorough and systematic assessment of the mucosa throughout the colon and ileum to accurately assess the pattern and extent of disease.
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The use of a validated endoscopic scoring system for grading of endoscopic IBD activity is important for improved standardization and communication of endoscopy findings, for monitoring endoscopic response to therapy, and for prognosis.
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Histologic evaluation should include assessment for features of chronicity, including crypt architectural distortion, basal plasmacytosis, and increased cellularity of the lamina propria, and can be essential in distinguishing IBD from acute self-limited colitis.
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Upper endoscopy with biopsies should be performed in all pediatric patients with suspected IBD, and in adult patients with suspected IBD and upper gastrointestinal symptoms.
Introduction
The diagnosis of inflammatory bowel disease (IBD) is based on established clinical, endoscopic, radiologic, and histologic features. In a patient presenting with suspected IBD, the initial endoscopic evaluation is an indispensable tool, valuable in determining the correct disease diagnosis, extent and severity of disease, and prognosis. The distinction between Crohn’s disease (CD) and ulcerative colitis (UC) is made accurately in greater than 85% of patients, and this distinction can have important ramifications for future medical and surgical therapies. The American Society for Gastrointestinal Endoscopy guidelines recommend a full colonoscopy with ileal intubation in all patients with a clinical presentation suggestive of IBD, unless contraindicated by the presence of severe colitis or toxic megacolon. This article discusses important macroscopic findings on the first endoscopy in suspected IBD, histopathologic interpretation of biopsy specimens, endoscopic scoring systems, and prognostic implications.
Introduction
The diagnosis of inflammatory bowel disease (IBD) is based on established clinical, endoscopic, radiologic, and histologic features. In a patient presenting with suspected IBD, the initial endoscopic evaluation is an indispensable tool, valuable in determining the correct disease diagnosis, extent and severity of disease, and prognosis. The distinction between Crohn’s disease (CD) and ulcerative colitis (UC) is made accurately in greater than 85% of patients, and this distinction can have important ramifications for future medical and surgical therapies. The American Society for Gastrointestinal Endoscopy guidelines recommend a full colonoscopy with ileal intubation in all patients with a clinical presentation suggestive of IBD, unless contraindicated by the presence of severe colitis or toxic megacolon. This article discusses important macroscopic findings on the first endoscopy in suspected IBD, histopathologic interpretation of biopsy specimens, endoscopic scoring systems, and prognostic implications.
Perianal examination
Patients with IBD can present with a myriad of symptoms including diarrhea, rectal bleeding, abdominal pain, nausea, vomiting, weight loss, and fecal urgency. Colonoscopic evaluation is one of the first steps in assessment of these symptoms. Before the initial colonoscopy, it is important to perform a careful perianal inspection and digital rectal examination because it may reveal clues to the diagnosis of CD, including the following :
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Anal skin tags, particularly type 1
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Anal fissure
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Deep anal canal ulcer
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Perianal fistula
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Perianal abscess
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Anorectal stricture
Type 1 anal skin tags are sometimes referred to as “elephant ears” and can have a varied appearance. They are present in up to 40% of patients with IBD, occurring in patients with CD, but rarely in UC. They are often painless but can become painful, at times associated with exacerbation of colonic disease.
Anal fissures, ulcerations in the lining of the anal canal distal to the dentate line, are present in about 30% of patients with perianal disease. As with idiopathic anal fissures, these most often occur in the midline but can also occur eccentrically. Multiple, nonhealing, painless, or eccentrically located anal fissures should raise the suspicion for a diagnosis of CD.
A hallmark of perianal involvement in CD is perianal fistulae, which occur in up to 45% to 50% of patients over the course of their disease and may be a presenting symptom in 20% to 30% of patients. It is more common in patients with Crohn’s colitis. Fistulae can arise from inflamed or infected anal glands or from penetration of fissures or ulcers of the rectum or anal canal. They may appear as abnormal perianal openings or as small pustules. Gentle compression adjacent to the orifice may express purulent material or stool. It is important to look for areas of fluctuance and tenderness, or pain on digital rectal examination, which could indicate the presence of an abscess. The development of a new perianal rigid mass in a patient with long-standing perianal disease should raise the suspicion of a perianal squamous cell carcinoma.
Examination of colonic mucosa during endoscopy
The normal colon lining appears smooth and glistening salmon-pink in color, with a transparent surface mucosa and a visible network of branching vessels beneath ( Fig. 1 ). Assessment of the mucosa should include an assessment of the vascular pattern, and evaluation for the presence of erythema, edema, granularity, friability, ulcerations, and spontaneous bleeding. In IBD and other types of intestinal inflammation, the normal vascular pattern can be obliterated and the mucosa can develop the aforementioned characteristics of inflammation, even deep crater-like ulcerations in severe cases. The macroscopic appearance on endoscopy is not conclusive for the diagnosis of IBD, but in conjunction with histology and clinical presentation, it may provide important information in considering a broad differential diagnosis that includes infectious enterocolitis, ischemia, drug-induced injury, Behçet disease, and segmental colitis associated with diverticulosis ( Table 1 ).
| Differential Diagnosis | Classic Clinical Presentation | Endoscopy Findings | Histology Findings |
|---|---|---|---|
| Cytomegalovirus colitis |
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|
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| Clostridium difficile colitis |
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| Other infectious colitides (ie, Campylobacter , Salmonella , Shigella , Escherichia coli , Entamoeba histolytica , sexually transmitted proctitides, intestinal tuberculosis) |
|
|
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| Ischemic colitis |
|
|
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| Nonsteroidal anti-inflammatory drug–induced injury |
|
|
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| Behçet disease |
|
|
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| Segmental colitis associated with diverticulosis |
|
|
|
The earliest response to tissue injury in UC is an increase in surface blood flow leading to erythema, vascular congestion, and edema, which can appear as “wet sandpaper.” On the first colonoscopy, the typical endoscopic feature is the presence of continuous inflammation extending proximally from the anal verge, often characterized by erythema, edema, and ulceration ( Fig. 2 ). The degree of inflammation classically increases in a proximal to distal pattern. There is often a line of demarcation at the proximal extent of disease, with an abrupt transition to normal mucosa.
The earliest endoscopically visible lesion in CD consists of very small punched-out ulcers in an otherwise normal-appearing mucosa, also called aphthous ulcerations. As disease severity increases, deeper ulcers involving all or part of the colonic wall can develop. Cobblestoning is a hallmark feature of CD that occurs when long linear or serpiginous ulcers course along the longitudinal axis of the colon, with intervening areas of normal or inflamed tissue ( Fig. 3 ). Lesions in CD are often discontinuous and adjacent to normal tissue, resulting in “skip lesions.”
The index colonoscopy and biopsies are accurate in distinguishing CD from UC in 89% of cases. However, this differentiation is challenging at times. Features that raise suspicion of CD include the following:
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Rectal sparing
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Patchy colitis or skip lesions
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Discrete ileal ulcerations
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Isolated ileal inflammation
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Extensive ileal involvement
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Ileal or ileocecal (IC) valve narrowing
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Cobblestoning of mucosa
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Long linear or serpiginous ulcers
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Deep ulcers
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Aphthous ulcers
Many of these features are suggestive, but not confirmatory, for a diagnosis of CD. For example, cobblestoning and deep ulcers can be seen in severe UC.
In approximately 10% of patients, their colonic disease cannot be classified into either of these categories, and it is termed IBD, type unclassified. The distinguishing endoscopic findings are particularly useful at the time of diagnosis, because the endoscopic appearance can change with treatment and patchy healing can occur. In one study of patients with UC, 44% had patchy colitis and 13% had rectal sparing after treatment.
Cecal patch
Despite the general tenet that patchy or segmental colitis is consistent with CD, isolated inflammatory changes around the appendiceal orifice without adjacent colonic inflammation are seen in UC. This finding is termed a cecal patch or a periappendiceal red patch. The rate of cecal patch ranges from 8% to 75% in some studies. It tends to parallel the inflammatory activity seen in the distal colon. It is more commonly seen in younger patients with longer disease duration, and thus far has not been shown to have any impact on disease remission, relapse, proximal extension, or dysplasia or cancer risk.
Rectal sparing
Rectal sparing is classically thought to be consistent with CD. However, atypical endoscopic findings at diagnosis can occur in a subset of patients with UC, more commonly in the pediatric population. Although histologic sparing is less common, macroscopic and histologic sparing have been reported. In children, relative rectal sparing (defined as reduced histologic severity and chronicity compared with more proximal colon) occurs in up to 23%, whereas full macroscopic rectal sparing occurs in 5% or less. In addition, patchy inflammation throughout the colon may occur in pediatric patients with UC before therapy.
In adults, this phenomenon is less frequently recognized, although more than half of patients with primary sclerosing cholangitis with UC have rectal sparing, possibly representing a separate disease phenotype. In a 2014 Korean study, 19.2% of patients with UC had patchy inflammation based on macroscopic visualization alone on the initial colonoscopy, with 3.3% rectal sparing. Another study showed rectal sparing at diagnosis to be rare in adults. In general, the presence of rectal sparing at first colonoscopy should suggest a diagnosis of CD.
Intestinal stricture
Although most patients present with pure inflammatory disease at diagnosis, 11% of patients with CD have strictures at initial evaluation. Strictures are most commonly located in the ileum and ileocecal valve; however, they can occur at any site in the gastrointestinal (GI) tract. Per the National Cooperative Crohn’s Disease Study, small bowel strictures occur in 25% of patients and colonic strictures in 10% of patients, although these numbers preceded the use of immunosuppressive and biologic drug treatment.
When a stricture is encountered in CD, it is important to assess for inflammation of the stricture itself and the adjacent mucosa. If traversable, the length and diameter of the stricture should be estimated. Multiple biopsies should be taken within and around the stricture to assess for dysplasia, with special attention paid to colonic strictures. Stricturing and penetrating disease complications may occur in the same patient, but fistulas can be difficult to visualize on colonoscopy.
Colonic strictures can also occur in patients with UC, but they are far less common, estimated in about 1% of patients ( Fig. 4 ). The historical teaching is that these strictures should be considered malignant until proven otherwise. A retrospective study of 1156 patients with UC showed a 24% prevalence of malignancy within UC strictures. A more recent case control study showed a much lower rate of malignancy, but the rate was elevated compared with patients without strictures. If encountered on the first colonoscopy, it is imperative to carefully survey all UC strictures with multiple biopsies.
Related posts:
Capsule Endoscopy and Deep Enteroscopy in Inflammatory Bowel Disease
Role of Histologic Inflammation in the Natural History of Ulcerative Colitis
Noninvasive Testing for Mucosal Inflammation in Inflammatory Bowel Disease
The Gastroenterologist’s Role in Management of Perianal Fistula
Motility Evaluation in the Patient with Inflammatory Bowel Disease
Dilation of Strictures in Patients with Inflammatory Bowel Disease
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