Review for 10.1186/s12876-019-1045-6 (2019)

Reviewer ’s report  
 
Title:  Clinical value of DPOC for detecting and removing residual common bile duct stones 
(video)  
 
Version: 0 Date: 12 Mar 2019 
 
Reviewer:  Huseyin  Alkim  
 
Reviewer’s report:  
 
This is an interesting manuscript evaluating the role of direct peroral cholangioscopy (DPOC) in 
detecting (and removing) residual common bile duct stones.  
 
There a re too many language and spelling errors. Please check and correct.  
 
I think that it is not correct to use the term of "lithotomy" for the stone removal done during 
ERCP procedure. Because the meanings of lithotomy are: 1 -surgical incision of the urinary 
bladder for removal of a stone, 2 -surgical removal of a calculus (stone) from the bladder, kidney, 
or urinary tract, 3 - surgery to remove one or more stones from an organ or duct. ERCP is not a 
surgical procedure.  
 
To avoid confusion, do not use different na mes for the same tool. Example; endoscope, ultrathin 
endoscope, gastroscope, gastroendoscope … names were used for the tool used for doing DPOC.  
 
I think that the exclusion criteria "a common bile duct diameter of<10mm" was not appropriate. 
If the diameter of bile duct was not return to normal or near normal after extraction of stones, I 
think that there is some stones left. And continue to check the bile duct with basket and/or 
balloon.  
 
The general characteristics of the patients included in the study shou ld be given as a table in a 
comparative manner with the excluded group.  
 
They stated that they excluded patients with gallbladder stones from the study. However, 17 
patients later had cholecystectomy. What is the indication of cholecystectomy?  
 
Endoscopic pa pillary balloon dilatation was done to the most of the patients. Why?  
 
The time between ERCP and DPOC is not clear. This information should be given in detail.  
 
At discussion section they wrote that "the residual stone rate by DPOC was similar to patients 
with cholecystolithiasis". There is no information about this in the study.  
 
"In the present study, a nearly 95% success rate was obtained using the direct insertion method 
or ordinary guidewire, and the operation was simple and the time was short." There is a mistake 
in this sentence. Because they used overtube in %10 of patients.  
When I see a cholangiogram similar to the one presented at figure 3d, I think that there are 
remained stones within the bile duct. And continue ERCP.  
 
The quality of video was very p oor. 
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
No 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
No 
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
No 
 
Are you able to assess any statistics  in the manuscript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further 
assessment in your comments to the editors.  
 
Not relevant to this manuscript  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Not suitable for publication unless extensively edited  
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following questions:  
 
1. Have you in the past five years received reimbursements, fees, funding, or salary from an 
organisation that may in any way gain or lose financially from the publication of this 
manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares in an organisation that 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 financial 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 competing interests' 
below. If your reply is yes to any, please give details below.  
 
I declare that I have no competing interests  
 
I agree to the open peer review policy of the journal. I understand that my name will be included 
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responses. I agree for my report to be made available under an Open Access Creative Commons 
CC-BY license ( http://creativecommons.org/licenses/by/4.0/ ). I understand that any comments 
which I do not wish to be included in my named report can be include d as confidential comments 
to the editors, which will not be published.  
 
I agree to the open peer review policy of the journ al