Rectal polyps extending to the dentate line (RPDL) pose a technical challenge to endoscopic resection due to the narrow lumen, rich venous/ haemorrhoidal plexus, and proximity to the skin. The traditional method of managing such lesions involved major surgery until minimally invasive surgery was developed. The resection of RPDL entered the realm of endoscopists with the advent of endoscopic mucosal resection (EMR), however EMR has been found to have a higher recurrence rate compared with transanal endoscopic microsurgery, albeit carrying a lower risk of complications. Endoscopic submucosal dissection (ESD) allows for endoscopic resection of RPDL with low recurrence and complication rates. However, this technique has a steep learning curve, especially in the hands of Western endoscopists. Knife-assisted snare resection (KAR) allows for precise mucosal incision at the dentate line and the dissection of the polyp from the anorectal junction. We aimed to assess the feasibility, safety, and efficacy of KAR for RPDLs.
This was a prospective observational study of patients who underwent KAR with a mean follow-up of 32 months (range: 1–83 months). All procedures were conducted on a day-case basis and were carried out under sedation by two endoscopists using high definition gastroscopes with a distal transparent cap. The polyp margin on the anal side was injected with a lifting solution consisting of succinylated gelofusin, indigo carmine, 1% lignocaine, and adrenaline. Haemostasis was maintained using a combination of the endoscopic knife and Coagrasper (Olympus, Tokyo, Japan). A mucosal incision was extended around the margins of the polyp, followed by submucosal dissection to facilitate snare deployment and achieve complete polyp resection. Post-procedural antibiotics were not routinely given.
A total of 40 patients (20 females, median age of 69 years) underwent KAR for RPDLs over the study period. The mean polyp size was 50 mm (range: 12–150 mm) and 32.5% of them were scarred from previous resection attempts. Curative resection after a single KAR was achieved in 33 (82.5%) patients. Further KARs were required by 7 patients leading to a total curative resection rate of 97%. The risk factors for multiple resections are polyps measuring >60 mm and encompassing >50% of the circumference (p<0.01). Overall, there was one complication where the patient had delayed bleeding which was managed conservatively. None of the patients experienced perforation or post-procedural sepsis.
This is the largest reported series of KARs for RPDLs. Our data demonstrated that for Western endoscopists, KAR is a very safe and effective technique in the treatment of RPDLs. The need for this technique has been questioned, as EMR has been shown to be effective in managing RPDL. However, it has been clearly demonstrated that the recurrence rate is higher with EMR than ESD and there is a need for improvement. A further query is why one should bother with KAR or hybrid ESD when a full ESD takes approximately the same time. This may be the case with Eastern endoscopists but ESD is not a commonly used technique in the West. However, KAR may act as a bridging technique for Western endoscopists familiar with the EMR technique, enabling them to master ESD, especially for the management of RPDL.