Objective Colonoscopy is the accepted gold standard for detecting colorectal adenomas, but the miss rate, especially for small and flat lesions, remains unacceptably high. The aim of this study was to determine whether enhanced mucosal contrast using pancolonic chromoendoscopy (PCC) allows higher rates of adenoma detection.

Methods In a prospective, randomised two-centre trial, PCC (with 0.4% indigo carmine spraying during continuous extubation) was compared with standard colonoscopy (control group) in consecutive patients attending for routine colonoscopy. The histopathology of the lesions detected was confirmed by evaluating the endoscopic resection or biopsy specimens.

Results A total of 1008 patients were included (496 in the PCC group, 512 in the control group). The patients' demographic characteristics and indications for colonoscopy were similar in the two groups. The proportion of patients with at least one adenoma was significantly higher in the PCC group (46.2%) than in the control group (36.3%; p=0.002). Chromoendoscopy increased the overall detection rate for adenomas (0.95 vs 0.66 per patient), flat adenomas (0.56 vs 0.28 per patient) and serrated lesions (1.19 vs 0.49 per patient) (p<0.001). There was a non-significant trend towards increased detection of advanced adenomas (103 vs 81; p=0.067). Mean extubation times were slightly but significantly longer in the PCC group in comparison with the control group (11.6±3.36 min vs 10.1±2.03 min; p<0.001).

Conclusions Pancolonic chromoendoscopy markedly enhances adenoma detection rates in an average-risk population and is practicable enough for routine application.