Current Progress of Endoscopy in Inflammatory Bowel Disease: Colonoscopy

Fig. 2.1

Sporadic cancer of the colon. High-definition white-light endoscopy (a), chromoendoscopy with indigo carmine spraying on the target lesion (b), and corresponding narrow-band imaging with magnification (c). Boundary of the lesion is distinctly visualized

Fig. 2.2

Dysplasia in quiescent ulcerative colitis. High-definition white-light endoscopy (a), and corresponding narrow-band imaging (b). The margin of the lesion is less distinct, compared to sporadic cancer shown in Fig. 2.1

NBI magnifying observation is also useful for the evaluation of MH in UC. Mucus adhesion often mimics erosion on normal observation, but presence or absence of epithelial defects is distinctly visible on NBI magnifying observation (Fig. 2.3).

Fig. 2.3

High-definition white-light endoscopy (a) in a case of ulcerative colitis. White area in the square in (a) mimics mucus adhesion over the mucosa. Narrow-band imaging with magnifying observation of the corresponding area (b) shows mucosal defect clearly

Both CS and MRI are diagnostic modalities of choice for the evaluation of colonic lesions of Crohn’s disease (CD) [5]. Among the problems of CS in CD is the difficulty of inserting a scope in the presence of adhesion or stenosis [6]. Availability of a narrow-caliber colonoscope with passive bending mechanism and balloon-assisted enteroscope has reduced this problem. A recently developed colonoscope, Olympus PCF-PQ260L (Fig. 2.4), has outside diameter of 9.2 mm and effective length of 1680 mm, and provides passive bending mechanisms in addition to the usual manipulative bending of the scope tip. It produces less discomfort, and patients’ acceptability for future examination is higher [7].

Fig. 2.4

Narrow-caliber colonoscope with passive bending mechanism (Olympus PCF-PQ260L)

The balloon-assisted enteroscope can shorten the intestinal tract by fixing the intestine with a balloon, and it can be easily inserted, particularly in otherwise difficult cases. In our experience with cases with failure of cecal insertion by regular colonoscopes, 94.8% were successful by PCF-PQ260L (36/38), and 100% by double balloon-assisted enteroscopes (EN-450T5, EC-450BI5).

In severely active UC, risk of perforation or exacerbation associated with endoscopic insertion is known. As a less invasive modality, in addition to ultrasound, CT-, and MR-colonography, the use of the colon capsule endoscope (CCE) has been attempted [8]. CCE can inspect the entire colon without producing discomfort (Fig. 2.5). A multi-center study to evaluate its efficacy and safety is undergoing as a research project of the Research Group of the Ministry of Health, Labor and Welfare of Japan.

Fig. 2.5

An image of colon capsule endoscopy in the ascending colon of a patient with ulcerative colitis

2.4 Diagnosis of IBD and Differential Diagnosis

2.4.1 Ulcerative Colitis

Diagnosis of IBD should not entirely depend on endoscopy. Comprehensive diagnostic approach, including history, physical examination, stool bacteriology, and histopathological finding, is necessary.

Although there is some controversy about worsening of UC by bowel preparation for colonoscopy, poor preparation precludes observation of diffuse inflammation and submucosal capillary network, discrimination of hyperemia from erosion, and estimation of the depth of ulcers. At least for initial diagnosis, evaluation of mucosal healing, and cancer surveillance, excellent bowel preparation by whole gut lavage is desirable.

The typical endoscopic image of UC is continuous and diffuse mucosal roughness or fine granularity extending from the rectum toward proximal portion, with hyperemia, edema, exudation, friability, erosions, ulcers, and inflammatory polyps. For hyperemia, edema and friability, inter-observer difference is higher, while it is low for vascular network, erosions, and ulcer. Not infrequently, skipped lesion is observed in the orifice of the appendix.

Moreover, in the early phase after the onset or a longstanding case particularly on treatment, rectal sparing and discontinuity of inflammation are occasionally encountered. Even without endoscopic inflammation, histological inflammation is frequently observed. Therefore, biopsy from endoscopically inactive mucosa including the rectum occasionally contributes to the confirmation of continuity of inflammation. According to the distribution of inflammation, each case of UC can be classified to proctitis, (distal colitis), left-sided colitis, extensive colitis, and right-sided or segmental colitis. This is important for selection of topical therapy. Although there are several different endoscopic severity indices available, most Japanese endoscopists apply the endoscopic severity classification of the Ministry of Health, Labor and Welfare in Japan, as well as Mayo endoscopic sub-scores.

In the differential diagnosis of UC, radiation enteritis, drug-induced enteritis, ischemic colitis, infectious enterocolitis (salmonellosis, Campylobacter infection, E. coli infection, tuberculosis, amebic dysentery, cytomegalovirus infection, etc.), Crohn’s colitis, and Behcet’s disease should be considered. Among them, the most important is infectious colitis, in which inflammation is not entirely diffuse or continuous, but often skipped. Bacterial cultures of stool, suctioned fluid in the colonic lumen, and biopsied tissue specimen during colonoscopy all contribute to accurate diagnosis. Campylobacter enterocolitis sometimes exhibits continuous inflammation and mimics UC, but in 80% of cases of the former, ulcer is noted on the ileocecal valve, and this finding is helpful for differential diagnosis. Diffuseness and continuity of inflammation is also important to differentiate Crohn’s colitis.

Amebic dysentery is rather important disease in Japan, and even more in tropical countries. There were 1582 cases of Entamoeba histolytica infection (0.79/100,000) in 2012–2013, 84.3% of which were intestinal amebiasis (National Institute of Infectious Diseases website). Endoscopic findings include erosions and ulcers with adhered white coating mixed with blood, showing dirty appearance. The cecum and the rectum are predominantly involved. Diagnosis is established by identifying amoeba trophozoites in stool or biopsy specimens, as well as serum antibody.

Since many UC patients receive immunosuppressive therapy, concomitant cytomegalovirus (CMV) infection should be in mind. The typical endoscopic finding is a discrete deep ulcer. Diagnosis is established by blood CMV antigen and biopsy (nuclear inclusions, immunostaining, PCR)

2.4.2 Crohn’s Disease

CD results in a full-thickness inflammation in all of the digestive tract. Predominant sites are the terminal ileum and the cecum. Ideally, the entire digestive tract should be investigated at the time of initial evaluation. The esophagus, the stomach, and the duodenum are inspected by upper gastrointestinal endoscopy, and the terminal ileum and the anus should be inspected during colonoscopy. Field of observation for the ileal lesions by colonoscopy is limited. Concomitant use of small intestinal radiography, CT/MR enterography, balloon-assisted enteroscopy, and video capsule endoscopy are often required. Small intestinal radiography, CT/MR enterography, and video capsule endoscopy are capable of observing the entire small intestine. CT and MR can evaluate inflammation of the intestinal wall and the adjacent area. Endoscopy has advantage of direct visualization, and is superior for the observation of fine lesions such as erosions and aphthous ulcers [9]. Balloon-assisted enteroscopy in more popular in facilities in Japan, compared to those in Europe and North America.

Longitudinal or serpiginous ulcers and cobblestone appearance are typical endoscopic findings of CD (Fig. 2.6a). Presence of non-caseating granuloma in the biopsy specimen may assure the diagnosis of CD. Irregular small ulcers, aphthous ulcers, erosions are also observed. Aphthous ulcers characteristically present in longitudinal distribution (Fig. 2.6b). In upper gastrointestinal endoscopy, bamboo-like notches are sometimes observed, interposing a normal mucosa (skip lesion).