Capsule endoscopy in inflammatory bowel disease

Abbreviations

Introduction

Video capsule endoscopy (VCE) was cleared for the diagnosis of small bowel disease, especially for obscure gastrointestinal (GI) bleeding, by the United States Food and Drug Administration in 2001. Various formats of VCE have been developed, including conventional VCE of the small bowel or colon, and wide-angle panoramic, panenteric, and small bowel and colon (SBC)–VCE . With advances in imaging technology, the already highly sensitive VCE in the detection of small bowel disease still suffers from suboptimal specificity .

The parameters of various capsule endoscopies are compared in Table 17.1 . VCE provides a noninvasive method to visualize the small intestine via high-quality images in patients with a wide spectrum of disorders such as Crohn’s disease (CD), ulcerative colitis (UC), ileal pouch disorders, obscure GI bleeding, polyposis syndromes, celiac disease, small bowel tumors, and other inflammatory disorders.

Crohn’s disease

CD is a chronic inflammatory disease that can involve the entire GI tract, from the mouth to the anus. Small bowel involvement occurs in more than 50% of patients with CD. According to the current guidelines , VCE has been recommended as an adjunct endoscopic modality. VCE is indicated for suspected, known, or relapsed CD when ileocolonoscopy and imaging studies are not feasible or conclusive. In addition to diagnosis and differential diagnosis, VCE can also be used in monitoring disease activity and response to treatment as well as evaluating postoperative recurrence of CD . VCE can reliably assess mucosal healing ( Fig. 17.1 ).

Routine small bowel imaging or the use of the patency capsule prior to capsule endoscopy is not recommended in patients with CD . However, in patients with obstructive symptoms or known stenoses, dedicated small bowel cross-sectional imaging modalities such as magnetic resonance enterography (MRE) or computed tomography enterography (CTE) should be performed first. Capsule endoscopy is normally not recommended in patients with chronic abdominal pain or diarrhea.

The common features of CD on VCE include edema, hyperemia, bleeding, exudates, aphthae, erosions, small (≤0.5 cm) and large (>0.5 cm) ulcers, denuded mucosa, and pseudopolyps. The shape of ulcers can be round, linear, circumferential, or stellate ( Figs. 17.2 and 17.3 ). VCE may also detect the primary (i.e., disease associated) or secondary (e.g., anastomotic or drug induced) strictures ( Fig. 17.4 ). The disease can be patchy, segmental, or diffuse. Two scoring systems are used to assess the activity of small intestine mucos, based on the type, location, and severity of small bowel lesions: the Lewis score and the Capsule Endoscopy Crohn's Disease Activity Index (CECDAI). These scoring systems facilitate the assessment of the course of small bowel CD and response to medical therapy. It should be noted that these scoring systems can quantitatively describe the type, distribution, and severity of mucosal lesions, but they cannot be used as initial diagnostic tools. The CECDAI is the sum of the respective scores for the proximal and distal segments of the small bowel in which the segments are defined by the small bowel transit time (SITT) of the capsule. The total score of each segment, proximal or distal, is the sum of the stricture score and the product of the scores for inflammation and extent of disease for that bowel segment. Thus the CECDAI score is based on the inflammation, extent of disease, and presence of strictures of the proximal or distal segments of the small bowel ( Table 17.2 ) .

In 2008 a capsule endoscopy scoring index, also named as the Lewis score, was proposed by Gralnek et al. . The Lewis score is a cumulative scoring system that is based on the presence and distribution of villous edema, ulceration, and stenosis . A score <135 is defined as normal or clinically insignificant mucosal inflammatory change. A score between 135 and 790 is mild, and a score ≥790 is moderate to severe ( Table 17.3 ) .

It is difficult for VCE to differentiate CD from nonspecific small lesions or other diseases such as lymphoma, ischemic bowel, small bowel tuberculosis, or drug-induced enteropathy, nonsteroidal antiinflammatory drugs (NSAIDs) in particular ( Fig. 17.5 ). NSAIDs should be discontinued at least 4 weeks prior to small bowel capsule endoscopy in the setting of suspected CD. As a screening tool for CD, capsule endoscopy has high sensitivity and low specificity but is not recommended for determining the initial diagnosis . Rather, the initial diagnosis should be based on clinical features, serum parameters, imaging conventional endoscopy, histology, and sometimes response to medical therapy. Endoscopic mucosal healing has been established as an important target for the treatment of CD as well as UC. In addition to conventional ileocolonoscopy, VCE has been shown to be effective for the measurement with mucosal healing .