Underwater endoscopic mucosal resection is associated with fewer recurrences and earlier curative resections compared to conventional endoscopic mucosal resection for large colorectal polyps.
Studies comparing the efficacy and safety of conventional saline-assisted piecemeal endoscopic mucosal resection (EMR) to underwater EMR (UEMR) without submucosal lifting of colorectal polyps are lacking. The objective of this study was to compare the efficacy and safety of EMR to UEMR of large colorectal polyps.



Two hundred eighty-nine colorectal polyps were removed by a single endoscopist from 7/2007 to 2/2015 using EMR or UEMR. 135 polyps (EMR: 62, UEMR: 73) that measured ≥15 mm and had not undergone prior attempted polypectomy were evaluated for rates of complete macroscopic resection and adverse events. 101 of these polyps (EMR: 46, UEMR: 55) had at least 1 follow-up colonoscopy and were studied for rates of recurrence and the number of procedures required to achieve curative resection.



The rate of complete macroscopic resection was higher following UEMR compared to EMR (98.6 vs. 87.1%, p = 0.012). UEMR had a lower recurrence rate at the first follow-up colonoscopy compared to EMR (7.3 vs. 28.3%, OR 5.0 for post-EMR recurrence, 95% CI: [1.5, 16.5], p = 0.008). UEMR required fewer procedures to reach curative resection than EMR (mean of 1.0 vs. 1.3, p = 0.002). There was no significant difference in rates of adverse events.



UEMR appears superior to EMR for the removal of large colorectal polyps in terms of rates of complete macroscopic resection and recurrent (or residual) abnormal tissue. Compared to conventional EMR, UEMR may offer increased procedural effectiveness without compromising safety in the removal of large colorectal polyps without prior attempted resection.
Division of Gastroenterology and Hepatology, University of Virginia, Box 800708, Charlottesville, VA, 22908, USA.
Robert J
RJ
Schenck
Division of Gastroenterology and Hepatology, University of Virginia, Box 800708, Charlottesville, VA, 22908, USA.
Darius A
DA
Jahann
Division of Biostatistics and Epidemiology, University of Virginia, Box 800717, Charlottesville, VA, 22908, USA.
James T
JT
Patrie
Department of Pathology, University of Virginia, Box 800214, Charlottesville, VA, 22908, USA.
Edward B
EB
Stelow
Division of Gastroenterology and Hepatology, University of Virginia, Box 800708, Charlottesville, VA, 22908, USA.
Dawn G
DG
Cox
Division of Gastroenterology and Hepatology, University of Virginia, Box 800708, Charlottesville, VA, 22908, USA.
Dushant S
DS
Uppal
Division of Gastroenterology and Hepatology, University of Virginia, Box 800708, Charlottesville, VA, 22908, USA.
Bryan G
BG
Sauer
Division of Gastroenterology and Hepatology, University of Virginia, Box 800708, Charlottesville, VA, 22908, USA.
Vanessa M
VM
Shami
Division of Gastroenterology and Hepatology, University of Virginia, Box 800708, Charlottesville, VA, 22908, USA.
Daniel S
DS
Strand
Division of Gastroenterology and Hepatology, University of Virginia, Box 800708, Charlottesville, VA, 22908, USA. ayw7d@virginia.edu.
Andrew Y
AY
Wang
D018256:Adenomatous Polyps / Q000473:pathology / Q000601:surgery*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003111:Colonic Polyps / Q000473:pathology / Q000601:surgery*; D003113:Colonoscopy / Q000379:methods; D015179:Colorectal Neoplasms / Q000473:pathology / Q000601:surgery*; D000069916:Endoscopic Mucosal Resection / Q000379:methods*; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000601:surgery; D012189:Retrospective Studies
Adenoma recurrence; Colonoscopy; Colorectal polyps; Endoscopic mucosal resection; Underwater