Pressure dye-spray: a simple and reliable method for differentiating adenomas from hyperplastic polyps in the colon

Based on 10 years of experience with chromoendoscopy, our hypothesis was that colonic adenomas can be differentiated from hyperplastic polyps by use of a high-pressure spray-jet of dye (pressure dye-spray). To test the accuracy of pressure dye-spray, classification of colonic polyps as adenomas and hyperplastic polyps by pressure dye-spray and ordinary colonoscopic findings (shape, size, and color surface appearance) were compared.

Pressure dye-spray chromoendoscopy was performed by using 0.035% indigo carmine, a spray-type cannula, and a water pump. Polyps were first classified as adenomas or hyperplastic polyps by ordinary colonoscopic findings. One or more pressure dye-spray bursts were then focused on the polyp from a distance of 1 to 2 cm. Polyps were classified as adenomas only if oozing of blood was evident; otherwise, they were classified as hyperplastic polyps. A histologic diagnosis was obtained for all polyps, and the results of ordinary colonoscopic findings and pressure dye-spray were compared.

This study examined 1468 polyps (1201 adenomas, 267 hyperplastic polyps; mean diameter 4 mm). The sensitivities for polyp differentiation with pressure dye-spray and ordinary colonoscopic findings were, respectively, 97.9% and 73.4% (p < 0.0001); specificities were, respectively, 96.6% and 92.1% (p = 0.077).

Pressure dye-spray was found to be a reliable technique for differentiation between adenomas and hyperplastic polyps.