Detecting diminutive colorectal lesions at colonoscopy: a randomised controlled trial of pan-colonic versus targeted chromoscopy

Abstract

Background: Diminutive and flat colorectal lesions can be difficult to detect using conventional colonoscopic techniques. Previous data have suggested that pan-chromoscopy may improve detection rates. No randomised control trial has been performed examining detection rates of such lesions while controlling for extubation time and lavage effect. Aim: We conducted a randomised controlled trial of pan-colonic chromoscopic colonoscopy for the detection of diminutive and flat colorectal lesions while controlling for extubation time and lavage effect. Methods: Consecutive patients attending for routine colonoscopy were randomised to either panchromoscopy using 0.5% indigo carmine (IC) or targeted chromoscopy (control group). A minimum diagnostic extubation time was set at eight minutes with controls undergoing a matched volume of saline wash. Results: A total of 260 patients were randomised; 132 controls and 128 to pan-colonic chromoscopy. Extubation times did not differ significantly between the control (median 15 minutes (range 8-41)) and chromoscopy (median 17 minutes (range 8-39)) groups. The volume of IC used in the pan-chromoscopy group (median 68 ml (range 65-90)) and normal saline used in the control group (69 ml (range 60-93)) did not differ significantly. There was a statistically significant difference between the groups regarding the total number of adenomas detected (p,0.05) with significantly more diminutive (,4 mm) adenomas detected in the pan-chromoscopy group (p = 0.03). Pan-chromoscopy diagnosed more diminutive and flat lesions in the right colon compared with controls (p,0.05), with more patients with multiple adenomas (.3) detected using pan-chromoscopy (p,0.01). Hyperplastic lesions were more commonly detected in the pan-chromoscopy group compared with controls (p,0.001). More hyperplastic polyps were detected in the left colon (86% rectosigmoid) using chromoscopy compared with controls. Conclusion: Chromoscopy improves the total number of adenomas detected and enhances the detection of diminutive and flat lesions. Importantly, eight diminutive lesions had foci of high grade dysplasia. Chromoscopy may benefit patients, assuming a high risk of colorectal cancer, and help in risk stratification and planning follow up colonoscopy intervals.

The water method combined with chromoendoscopy enhances adenoma detection

“…The combined chromoendoscopy and water method was accomplished by adding 10 ml of 0.8% indigo carmine to a liter bottle of water used with the water method without having to perform dye spray separately as previously described. [10][11][12] A representative description of pan-and selective dye spray 11 is included for comparison. For pan-chromoscopy a chromoscopy diffusion catheter was used to apply a maximum of 150 ml of 0.5% indigo carmine to the entire mucosa during withdrawal from the cecum.…”

“…Chromoscopy was performed in 10 cm segments which were then re-inspected following aspiration of any excess indigo carmine forming pools in the colon. 11 Selective chromoscopy (2-5 ml of indigo carmine flushed down the side port of the colonoscope followed by a 20 ml air ''push'') delineated suspected mucosal lesions which had been identified by observing the mucosal signs (presence of erythema, focal pallor, hemorrhagic spots, absence of vascular network pattern, discrete mucosal unevenness, or deformity) without the prior use of chromoscopy. A minimum diagnostic extubation time from the cecum to the anus (excluding that required for interventional procedures) was set at eight minutes for all patients.…”

“…Since the water method [1][2][3][4][5][6][7][8][9] and use of chromoendoscopy [10][11][12][13][14] were reported to have beneficial impacts, a performance improvement project evaluating their utility was carried out at the Sacramento VA Medical Center in Mather, California. Data were collected prospectively to monitor performance and analyzed retrospectively.…”

“…8 Chromoendoscopy with pan colonic or targeted dye sprays has been shown to improve detection of colonic lesions. [10][11][12] Chromoendoscopy may be important also in the detection of non-polypoid colorectal neoplasms. 13 Despite these encouraging features chromoendoscopy for screening and surveillance has not been performed routinely by endoscopists in the United States (US).…”

Photometric stereo endoscopy

“…5,6 In chromoendoscopy, surface dyes that highlight topography are used, and lesion detection rates have been documented to increase. 7,8 Despite their recognized advantages, CTC and chromoendoscopy are infrequently used due to the increased cost associated with follow-up colonoscopy for CTC and the significant time required for chromoendoscopy.…”