Rectal and Rectosigmoid Endoscopy to Assess Endoscopic and Histological Remission in Ulcerative Colitis: A Prospective Study.

Background and aims: Despite increasing interest in endoscopic and histological remission as a treatment target in ulcerative colitis (UC), the accuracy of endoscopic and histological findings in the left colon and/or rectum to detect pancolonic remission is poorly known. We aimed to compare the diagnostic accuracy of rectosigmoidoscopy (RS) and rectoscopy for detecting endoscopic and histological healing elsewhere in the colon.

Methods: Consecutive UC patients who underwent colonoscopy were prospectively included. Endoscopic healing was defined by a Mayo endoscopic score (MES) = 0 on all explored segments and histological healing was defined by a Nancy index ≤ 1 (2 biopsies/segments). The agreement between colonoscopy, RS, and rectoscopy for endoscopic and histological healing was assessed using Cohen's kappa coefficient.

Results: Eighty patients were included. Thirty-four had an MES = 0 by RS and colonoscopy. The agreement between colonoscopy and RS was almost perfect, with a к index of 0.95 (%-agree 97.5) for Mayo 0, and к of 0.95 for Mayo 0-1 (%-agree 97.5, P < .0001). The agreement between RS and colonoscopy was also almost perfect (к = 0.877, (%-agree 91.7, P < .001) for the assessment of histological healing. The agreement between rectoscopy and colonoscopy for the evaluation of endoscopic (Mayo 0) and histological healing was almost perfect as well (к = 0.83 (%-agree 91.2, P < .001) and к = 0.80 (%-agree 91.7, P < .001)).

Conclusion: For UC patients undergoing treat-to-target interventions, endoscopic and histological findings in the rectum alone provide good accuracy for determining pancolonic endoscopic and histological remission. Rectal examination could be an alternative to RS for monitoring UC patients.