Deep dive into water-aided colonoscopy – underwater techniques without a splash

The infusion of water to aid colonoscopy dates back over several decades, with the evolution of the practice having covered many techniques. Investigators and practitioners have employed a combination of gas (air or CO2) and water without suction of the infused water during insertion (water immersion), or infusion of water with removal of water and debris, as well as residual gas, during insertion (water exchange), and underwater resection to remove lesions [1]. Underwater resection entails the immersion of polyps in water to assist polypectomy, underwater endoscopic mucosal resection (UEMR), and underwater endoscopic submucosal dissection (UESD). The technique without gas instillation reduces colonic distension and elongation, minimizing loop formation, decreasing pain, and enhancing the success of insertion in unsedated patients. Water exchange with the removal of infused water along with colonic debris during insertion improves the quality of bowel preparation during withdrawal in both unsedated and sedated patients, and minimizes cleaning-associated distractions in the search for polyps. Quality improvement with water exchange has shown increases in the adenoma detection rate, with the immersion of the polyps in water enhancing completeness and ensuring the safety of lesion removal.