We read with interest the article by Rutter et al (Gut 2004;53:256–60) and the letter in response to this article by Hata et al (Gut 2004;53:1722). Rutter demonstrated the advantage of magnifying chromoendoscopy using indigo carmine for detection of dysplasia compared with conventional colonoscopy without dye spray by back to back colonoscopy in patients with longstanding ulcerative colitis.

Hata et al discussed the characteristics and correct selection of dyes. In particular, Hata et al emphasised that there are two types of dye spraying: the contrast method in which dye is used solely to contrast the irregularity …