Randomised Tandem Colonoscopy of Narrow Band Imaging (NBI) and White Light Endoscopy in Patients With Endoscopic Piecemeal Mucosal Resection

Resection of large sessile polyps in the colon (usually more than 2 cm) or those nonpolypoid neoplastic lesions (also called laterally spreading tumors or LST), confers technical difficulty and often are forced to remove into fragmented resection or endoscopic piecemeal mucosal resection. This has been associated with a recurrence of 25%. For this reason, clinical guidelines recommend endoscopic follow-up at 2 to 6 months after piecemeal resection of colorectal polyps to check for residual neoplasia.

Narrow-Band Imaging (NBI, Olympus) improves visibility and identification of the surface and vascular structures of colon polyps. In contrast to conventional chromoendoscopy, it is easily activated by pressing a button on the endoscope.

Virtual or conventional chromoendoscopy are applied during resection of polyps defining the border of the lesion. However, there are few studies using Narrow Band Imaging and do not allow to know whether the use of this technique could improve the detection of residual tumor after fragmented polypectomy and avoid complications, time and costs of biopsy and histological analysis.

In this context, the European Society of Gastrointestinal Endoscopy (ESGE) has recently published the first Guideline of Advanced Endoscopic Imaging for the Detection and Differentiation of Colorectal Neoplasia and recommends conventional or virtual chromoendoscopy in patients with piecemeal polypectomy scar (strong recommendation, low quality evidence).

The investigators will perform a randomised, controlled trial of tandem colonoscopy using NBI and WLE. The main goal is to compare the rate of detected neoplasia between both techniques and evaluate the diagnostic accuracy of NBI and WLE to histology as the gold standard.