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RECTAL ESD IN AN EX VIVO BOVINE LARGE BOWEL MODEL VIA INDEPENDENT RETRACTION WITH GRASPER AND OVERTUBE PASSED THROUGH A TRANSANAL PLATFORM NOTABLY SHORTENS CASE TIME, DECREASES DEEP WALL INJURIES AND IMPROVES RESECTION QUALITY.
Neil Mitra
1, Elizabeth Nilsson Sjolander
*1,2, Yi-Ru Chen
1, Jorge Castro-Otero
1, Jeffrey Nussbaum
1, Kavita Jain
1, Hmc Shantha Kumara
1, Richard L. Whelan
11Lenox Hill Hospital, New York, NY; 2North Shore University Hospital, Manhasset, NY
Introduction: Endoscopic Submucosal Dissection (ESD), the gold standard large polyp removal method, is difficult in large part because gravity and the dissection cap are the sole means of retraction. The ESD adoption rate in the U.S. is low, thus, colectomy, with its attendant morbidity, is still done for many large polyps. If it were possible to retract the polyp edge then submucosal detachment would be far easier. This "randomized" study assessed the impact of independent transanal retraction-assisted rectal ESD (RA-ESD) vs standard ESD (S-ESD) technique in an ex vivo bovine colorectal model. Retraction was obtained with a semi-rigid thin overtube through which a more flexible grasper was passed.
Methods: Ex vivo bovine large bowel (with sphincter) was used and 2 cm diameter "lesions" tattooed onto the rectal mucosal surface via a colotomy (subsequently closed) and the proximal colon end zip tie closed. A 4 cm hollow transanal access platform with phalange was inserted and the gel cap (through which the colonoscope had been passed) attached to the anal sleeve. S-ESD and RA-ESD were alternately performed. As regards the latter, the planned resection line is marked with spot burns, a submucosal "lift" established, and the mucosa scored circumferentially. Next, the tissue grasper and semirigid overtube with 90 degree curved tip are passed through the gel cap. The cut edge of the distal edge of the polyp pelt is then grasped by the assistant with the grasper. Rotating the overtube with its curved tip lifts the polyp’s edge which exposes the submucosal attachments. The case times, number of injections, volume of lift fluid, pelt margin status, and deep bowel wall injuries were tracked.
Results: 11 bovine large bowel were used and a total of 46 ESDs performed (22 S-ESD and 24 RA-ESD). En bloc removal was achieved for all cases. The mean resection times were: S-ESD, 31.9 minutes; RA-ESD, 21.2 minutes (p<0.00001). The mean number of deep muscle injuries incurred was: S-ESD, 4.7; RA-ESD, 1.4 (p=0.00003). The mean number of lift injections was: S-ESD, 6.9; RA-ESD, 2.2 (p<0.00001). The mean volume of lift solution needed was: S-ESD, 101.9 ml; RA-ESD, 53.3 ml (p<0.00001).
Conclusions: The addition of an independent retractor after circumferential incision of the polyp margin greatly facilitated detachment as demonstrated by a 33% reduction in case length, 68% fewer lift injections, 48% less lift fluid required, and a 70% reduction in deep bowel wall injuries. As regards the performance of rectal ESD, in this model, the retractor-assisted method via a transanal platform was clearly superior as regards all parameters assessed. Clinical assessment of this method appears to be indicated.
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