The usefulness of PDS to distinguish adenoma from non-adenoma has been reported in DDW 1999. In this report, it was reassessed by using another pump with about half output power of the previously reported one, and the suitability of CCC-PDS for colorectal cancer screening was evaluated. Methods: An oral irrigator equipped with a foot switch was used as a water pump. Dye solution containing 0.035% indigo carmine and 0.059% diethylpolysiloxane (anti-bubble) was sprayed using a cannula (Olympus PW-5V-1) throughout the entire colorectum after advancement of the scope (Olympus CF-Q240 or Q140) to the cecum. Once a polyp was recognized, a few times of spray jet application were focussed on the polyp at a distance of 1 to 2 cm. Any polyp showing no bleeding, petechiae, or bleeding without outflow was categorized as PDS-, and any polyp showing bleeding with outflow was categorized as PDS+. Under stereomicroscope, all resected specimens including hot biopsied samples were made sure of containing all or part of the polyp, and then optimally sectioned. Results: The pressure on the polyp surface by the oral irrigator was almost same as that by maximum hand-spraying. Of 1381 resected polyps from 497 patients, 1235 polyps with a mean diameter of 4.1 mm were enrolled, excluding 41 of bad resected materials and 15 of difficulty to categorize as PDS+/-. With regard to the differentiation between adenomas and non-adenomas, PDS showed 97.4% and 97.1%; 92.8% and 92.6%; 96.7% and 96.5% of sensitivity, specificity and overall accuracy in small (<10 mm) and diminutive (<5 mm) polyps respectively. All polyps histopathologically diagnosed as severe atypia or carcinoma had been categorized as PDS+. Of 254 adenomas colonoscopically misdiagnosed as possible non-adenomas, 233 (91.7%) showed PDS+ meaning adenomas. Of 1021 adenomas, 63 (6.2%) were flat type in shape and 154 (15.0%) were only detected because of traumatic bleeding after PDS. Multiplicity rate were 73.5% of 249 adenoma-bearing patients. Average inspection time was 10min 57s, 13min 53s and 17min 30s in cases without resection, with one hot biopsy and with two hot biopsies respectively. Conclusions: CCC-PDS is suitable for colorectal cancer screening because 1) it is technically simple, 2) it is very effective in separating adenomas from non-adenomas, 3) it detects by traumatic bleeding adenomas that would otherwise be missed, 4) it have the possibility to detect much more adenomas including flat type than standard colonoscopy.