Underwater Endoscopy for Colorectal Neoplasia : Frontline Gastroenterol | Jun 2026

Introduction:

Water-assisted and immersion-based endoscopic techniques are increasingly transforming the diagnosis and treatment of colorectal neoplasia. Unlike conventional gas insufflation, these approaches replace luminal gas with water or saline, creating a different optical and mechanical environment within the gastrointestinal tract. This can improve lesion visualisation, facilitate endoscopic resection, and enhance patient comfort. Over the past decade, underwater techniques have evolved from simple insertion methods to advanced therapeutic platforms for complex colorectal lesions.

Problem Statement:

Despite major advances in colonoscopy and endoscopic resection, challenges remain in optimizing adenoma detection, improving procedural comfort, and achieving safe and effective removal of complex colorectal neoplasms. Conventional techniques may be limited by suboptimal visualisation, difficult lesion access, and procedural complexity. There is growing interest in whether underwater and immersion-assisted approaches can overcome these limitations and improve both diagnostic and therapeutic outcomes.

Summary:

This review highlights the expanding role of underwater endoscopy across the spectrum of colorectal neoplasia management. Water-aided colonoscopy (WAC) has been associated with improved patient tolerance, enhanced bowel cleanliness, better adenoma detection, and smoother procedural performance. Underwater endoscopic mucosal resection (U-EMR) has emerged as an effective technique for colorectal lesion removal, offering efficient resection with favorable outcomes and reduced recurrence in selected cases. More recently, saline-immersion strategies such as the Saline-Immersion/Irrigation Technique (SITE) have been incorporated into endoscopic submucosal dissection (ESD). By creating a fluid-filled operative field, SITE may enhance visualisation, provide buoyancy-assisted tissue traction, improve electrosurgical performance, and potentially reduce thermal injury. Early experience suggests that SITE-ESD may simplify technically demanding dissections and improve procedural safety. Collectively, underwater endoscopy is evolving into a comprehensive platform for colorectal neoplasia management, with growing evidence supporting its integration into routine and advanced endoscopic practice. Further standardization and prospective studies will help define its optimal role in modern therapeutic endoscopy.