The CDEIS has been developed to detect changes in endoscopic severity on the basis of characteristics of the ileocolonic mucosa [6]. The extent of mucosal lesions is quantified on a visual analogue scale from 0 to 10 in five sections of the bowel: ileum, right colon, transverse colon, combined sigmoid and left colon, and rectum (Table 17.1). The variables of the CDEIS are the presence of superficial ulceration, deep ulceration, the ulcerated and nonulcerated surface, and the presence of ulcerated/nonulcerated stenosis. The range of CDEIS is from 0 to 44. CDEIS is a standard, validated, and reproducible index. However, it is complex and difficult to score in clinical practice. The threshold of CDEIS for endoscopic remission is defined as CDEIS < 6, and complete endoscopic remission is defined by a value of CDEIS < 3 [7]. Mucosal healing in the study by Mary et al. was defined as only the absence of ulcers. They also defined endoscopic response as a decrease in CDEIS score >5 points. CDEIS was used as an endpoint in a clinical trial to demonstrate the efficacy of certolizumab [8]. The rates of endoscopic response, endoscopic remission, complete endoscopic remission, and mucosal healing at week 10 were 54%, 37%, 10%, and 4% respectively. At week 54, the corresponding rates were 49%, 27%, 14%, and 8% respectively, in patients who were treated with certolizumab. To date, however, there is no validated definition of endoscopic remission and mucosal healing in patients with CD.

The variables of SES-SD [9] are size of ulcers, ulcerated surface, affected surface, and the presence of narrowing (Table 17.2, Fig. 17.1). Each category is scored from 0 to 3 for the 5 bowel segments (rectum, sigmoid and descending colon, transverse colon, right colon, and terminal ileum). Thus, the total SES-CD ranges from 0 to 60. For endoscopists, the SES-CD is simpler than CDEIS for scoring the severity of disease. SES-CD is well correlated with CDEIS. Nevertheless, SES-SD has been less used than CDEIS in clinical trials, and it is also less used in clinical practice. Furthermore, only a study to validate SES-CD against CDEIS was previously conducted. There is no cutoff value of SES-CD for mucosal healing and endoscopic remission.

Figure 17.2 indicates endoscopic findings at the terminal ileum and each segment of the colon in CD patients with abdominal pain and several diarrhea. The Crohn’s disease activity index (CDAI) corresponding to those findings was 275.5. Endoscopic findings revealed deep longitudinal ulcerations and irregular ulcerations in the transverse colon and cecum (Fig. 17.2). Severe stricture with ulceration was observed at 5 cm from the ileocecal valve, and a colonoscope could not be passed through the stricture. The patient’s CDEIS and SES-CD scores were 19.3 and 28 respectively (Table 17.4a–b). The patient was treated with adalimumab (ADA) and responded to treatment. The CDAI decreased from 275.5 to 134.5 at 14 weeks after administration of ADA. Endoscopic findings at 14 weeks indicated that the severe inflammation with longitudinal ulceration markedly improved, although small ulcerations were still found at the transverse colon and rectum (Fig. 17.3). The CDEIS decreased from 19.3 to 3.5 (Table 17.5a), and the SES-CD decreased from 38 to 7 (Table 17.5b). The CDEIS and SES-CD changes were affected by endoscopic improvement in this patient. Even as clinical and endoscopic improvements were achieved, small ulcerations were still observed. This result is consistent with the observation of endoscopic improvement based on CDEIS (change of CDEIS > 5; 19.3 → 3.5), whereas complete endoscopic remission or mucosal healing was not obtained because the patient had a score of CDEIS >3 with ulceration at 14 weeks after treatment.

The Rutgeerts score [10] was developed to assess the severity of inflammation at the anastomosis and neoterminal ileum in patients with ileocecal resection. The Rutgeerts score includes rankings of i0, i1, i2, i3, and i4 (Table 17.3, Fig. 17.4). Although it is not validated, the prediction of relapse has been validated using this score. Scores of i0 and i1 indicate a low risk of clinical recurrence, whereas i3 and i4 correspond to a relatively high risk of recurrence. Although this score is useful to assess the severity of inflammation at the anastomosis, it is unclear how this score is determined in patients with any other colonic lesions.