Flat polyps: Endoscopic detection and treatment

Colonoscopy offers a method of screening for and prevention of colorectal cancer. Unfortunately, interval cancers still occur after negative screening colonoscopy suggesting that some pre-cancerous lesions may be missed. Flat and serrated polyps are a particular challenge to detect and may explain why some of these cancers occur. Detection of these subtle lesions requires recognition of their existence, training in their detection, careful inspection technique and adequate bowel preparation. Once a large, flat or otherwise complicated polyp is detected, endoscopic methods exist that offer an alternative to surgery. When performed by appropriately trained endoscopists in carefully selected patients, endoscopic resection can reduce the risk and morbidity of resection. In this review we define the types of difficult to detect polyps, methods to increase their detection, and describe available endoscopic resection techniques.