Second European evidence-based consensus on the diagnosis and management of ulcerative colitis Part 1: Definitions and diagnosis

### 1.1 Introduction Ulcerative colitis is a lifelong disease arising from an interaction between genetic and environmental factors, observed predominantly in the developed countries of the world. The precise aetiology is unknown and therefore medical therapy to cure the disease is not yet available. Within Europe there is a North–South gradient, but the incidence appears to have increased in Southern and Eastern countries in recent years.1,2...