Review for 10.1186/s12876-020-01457-y (2020)

Reviewer ’s report  
 
Title: Underwater versus conventional endoscopic mu cosal resection  for small size 
nonpedunculated colorectal polyps ：A randomized controlled trial  
 
Version: 0 Date: 22 May 2020  
 
Reviewer: Arnaldo Amato  
 
Reviewer's report:  
 
This is a retrospective study aimed at evaluating the efficacy and safety of UEMR in comparison 
with conventional endoscopic  mucosal resection of SMALL non -pedunculated colorectal polyps.  
 
The topic is interesting and original, the paper flows quite well, being fairly clear in the 
presentation of the contents with small exceptions.  
Moreover, some major and minor comments need t o be made on the weaknesses of the study:  
- First of all, UEMR is not performed only in water -aided colonoscopy and surely it was 
not designed in that setting as reported in Background. The execution of the technique, especially 
for small polyps, is more e asily pursued in water -aided colonoscopy and certainly allows for 
faster procedural time (which would certainly be longer in a colon not already filled with water).  
One of the issues to discuss when talking about UEMR is the procedural time. Comparing 
UEMR  with EMR, the time it takes to fill the lumen with water is expected to compensate for the 
time required to perform submucosal infiltration. This does not happen when we work in a lumen 
already full of water because we are performing a water -aided colonos copy. However, the 
routine removal technique for small polyps does not provide for infiltration, therefore UEMR is 
expected to be a little slower.  
- Second, it seems that the routine technique for removal of small polyps is EMR. For 
that reason, the Authors EMR has been used as referral method. The resection of these polyps is 
almost always carried out without sub -mucosal injections. As a consequence, the results of this 
study are scarcely applicable to clinical practice  
- Please replace "diminutive" with "small" in Abstract and Background. Diminutive 
polyps are those <5mm in size.  
- The definitions need to be checked, better specified and used uni quely throughout the 
text, as well as in the tables: i.e. AEs are better categorized as early and delayed bleeding  
(immediate attack doesn't sound well)  
- Please specify if the biopsies of the margins of resection were placed in a jar different 
from that  of the polyp  
- It's not clear if clipping has been used as prophylactic technique or only as treatment of 
bleeding. Please specify.  
- Height, weight and BMI are not relevant for the study and might be removed from the 
text 
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Yes 
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Yes 
 
Are you able to assess any statistics in the manus cript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please speci fy what aspects require further 
assessment in your comments to the editors.  
 
I am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Needs some language corrections before being published  
 
Declaration of competing interests  
Please complete a declaration of competing i nterests, considering the following questions:  
 
1.  Have you in the past five years received reimbursements, f ees, funding, or salary 
from an organisation that may in any way gain or lose financial ly from the 
publication of this manuscript, either now or in the future?  
 
2.  Do you hold any stocks or shares in an organisation t hat may in any way gain or 
lose financially from the publication of this manuscript, either now or in the 
future?  
 
3.  Do you hold or are you currently applying for any patents  relating to the content 
of the manuscript?  
 
4.  Have you received reimbursements, fees, funding, or salary from an organization 
that holds or has applied for patents relating to the content of the manuscript?  
 
5.  Do you have any other financia l competing interests?  
 
6.  Do you have any non -financial competing interests in relation to this paper?  
 
If you can answer no to all of the above, write 'I declare that I have  no compe ting interests' 
below. If your reply is yes to any, please give details be low. 
 
I declare that I have no competing interests  
 
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