Magnification chromo-colonoscopy

Chromoscopic colonoscopy using indigo carmine is indispensable for the accurate detection of flat neoplastic lesions. In particular, the dye spray technique facilitates the detection of both flat hyperplastic polyps and highly dysplastic lesions. However, magnification chromo-colonoscopy discriminates adenomas from hyperplastic polyps with greater accuracy than conventional methods by showing distinct and visible pit patterns. A pit pattern represents crypt orifices, which reflect the underlying histological structures and colonoscopists can make histological predictions by observing the pit patterns without obtaining biopsy specimens. The pit patterns are classified as types I, II, IIIL, IIIs, IV and V based on histological characterization of normal mucosa, hyperplastic polyp, polypoid adenoma, flat adenoma, tubulo-villous adenoma and cancerous tissue, respectively. In previous reports, overall accuracy ranged from 80 to 95%. In addition, magnification chromo-colonoscopy is useful for the diagnosis of early cancer associated with substantial invasion of the submucosa, in which type V pits are subclassified as types V-I and V-N. The presence of type V-N pits is significant in correlation to cancer with substantial invasion of the submucosa. Magnification chromo-colonoscopy is useful in clinical decision-making when deciding whether endoscopic resection or bowel resection is the appropriate initial procedure to treat lesions.