Patients with chronic ulcerative colitis (UC) have a better chance that precancerous lesions heralding adenomas will be apparent during surveillance if their colon is sprayed with contrast dye, an endoscopic study has found. Using this method routinely would be more efficient, requiring fewer biopsies and less histological screening.

Spraying with indigo carmine dye showed a strong trend towards detection: precancerous lesions (2–6 mm diameter) were detected in seven patients versus only two with standard endoscopic examination in the same 100 patients. A total of 2904 non-targeted biopsy specimens disclosed no cases of dysplasia; 43 targeted specimens—in the vicinity of any irregularity in colonic epithelium—showed two precancerous lesions on histological analysis, but it was the 114 specimens in 55 patients taken after dye spraying that yielded a further seven instances of precancerous lesions (in five patients), all thought to be adenomas.

Routine biopsy rates in the UK can be as low as 10 or fewer per patient or well below the 30–40 rate recommended by the American Society for Gastrointestinal Endoscopy, so the increased sensitivity of endoscopic surveillance with the dye is a clear benefit to UK patients, say the authors.

Patients with chronic UC for eight or more years underwent endoscopic surveillance and biopsy for precancerous lesions: once according to the American guidelines with non-targeted biopsies, plus targeted biopsies near visually suspicious areas of colon, then again, after 1% indigo carmine pancolonic spray in a back to back procedure, when additional visible abnormalities were biopsied.