Crohn’s disease (CD) and ulcerative colitis (UC) belong to chronic gastrointestinal condition called inflammatory bowel disease (IBD). The clinical course of both disorders is similar and their most common symptoms are abdominal pain, diarrhea, often with bloody stools and malnutrition, typical for pediatric population (1). IBD is characterized by exacerbations and spontaneous or drug-induced remissions. However, the histopathological features are different whether CD or UC. UC primarily affects the mucosa of the large bowel, while CD is a transmural disease that can affect the whole gastrointestinal tract (2). Moreover, the various clinical patterns are reflected in the microscopic features observed in biopsies obtained during endoscopy, which is used for monitoring of disease activity. Therefore, biopsies allow assessment of disease activity but also identification of pre-cancerous lesions and cancer, which apply rather to adult patients than pediatric population. In CD, in contrast with UC, the rectum is not always involved and lesions in this type of IBD frequently occur in a background of normal mucosa (3). Thus, it is more appropriate to take multiple endoscopic biopsies in different segments of the colon (and ileum) during both initial work-up of a patient and while monitoring treatment efficacy (4). However, endoscopic mucosal biopsies do not show all the characteristic features of CD. Therefore, the review of biopsies, in combination with clinical, laboratory, radiographic and endoscopic observations, is needed for both diagnosis and monitoring of IBD, and for the differentiation CD and UC from other conditions. In the last years, many disease-specific instruments, especially complex numeric activity indices to measure activity have been created (5). Objective measures of activity in CD are very useful not only in everyday work but also in clinical trials to enroll homogeneous groups of patients and to evaluate their response treatment. Therefore, in order to be widely used, activity indices should be simple and easily reproducible. In this article, we make a revision of available clinical, endoscopic and histopathological scales used in common practice for diagnosis and monitoring of CD.

There have been few activity indices proposed so far: the Simple index (or Harvey Bradshaw index) (6), the Organization Mondiale de Gastroenterologie (OMGE) index (7), the Cape Town index (8) and Crohn’s Disease Activity Index (CDAI) (9) with its pediatric version – PCDAI (10). However, only the last two are widely used in clinical practice. The CDAI was developed by Best et al. from the Midwest Regional Health Center in Illinois, in 1976 (9). The index consists of eight factors, each summed after adjustment with a weighting factor. The components of the CDAI and weighting factors are collected in table 1.