Review for 10.1186/s12876-020-01428-3 (2020)

Reviewer ’s report  
 
Title: Pancreatic duct guidewire placement for biliary cannulation as a risk factor for stone residue 
after endoscopic transpapillary stone removal  
 
Version: 0 Date: 02 Jul 2020  
 
Reviewer's report:  
 
I have read your interesting article indicating that the pancreatic duct guidewire (P -GW) method 
for biliary cannulation is a risk factor for stone residue after endoscopic biliary stone removal even 
when balloon -occlusion cholangiography is performed at t he end of the procedure. Although this 
novel finding appears to be of value, I recommend elaborating on the following concerns to 
increase the reliability and generalizability of your data.  
 
1. Please explain the rates of patients who underwent CT or MRI wi thin 2 months if these 
examinations were not performed for all patients.  
 
2. Please explain the reasons for performing CT or MRI to check for stone residue.  
 
 
3. Elaborate on the probable selection bias derived from 1 and 2 above.  
 
4. Clarify the definitions f or imaging findings for the residual stones. Although the authors 
mentioned the limited capability of intraductal ultrasonography to detect stones due to pneumobilia 
after endoscopic intervention, MRI has a similar difficulty. Moreover, CT cannot be used t o detect 
X-ray negative stones. In addition, describe if there were those in whom stone residue was not 
definitively found using CT and MRI but confirmed using endoscopic retrograde cholangiography 
(ERC). Elaborate on whether there were patients who did no t receive intervention for residual 
stones (i.e., did all patients who were diagnosed to have residual stones receive additional stone 
removal?).  
 
5. I recommend a more attractive title involving your new finding. For instance, "Pancreatic duct 
guidewire pl acement for biliary cannulation as a risk factor for stone residue after endoscopic 
transpapillary stone removal," "Pancreatic guidewire -guided cannulation as a predictive factor for 
stone residual after endoscopic biliary stone removal," or "Keeping a can nulation -aimed pancreatic 
guidewire during procedures of endoscopic biliary stone removal as a risk factor for stone residue."  
 
6. Endoscopic procedures, including endoscopic sphincterotomy (EST) and stone removal, are 
difficult with a pancreatic guidewire kept in place. Please describe whether there were patients 
from whom the guidewire was intentionally or inadvertently removed and whether the pancreatic 
guidewire was replaced. Moreover, please discuss the possibility of negative effects from keeping 
the w ire in place, such as prolonged procedure times, insufficient EST, and restricted applications 
of devices.  
 
7. Please clarify the number of endoscopic sessions for initial stone removal. Describe it clearly 
even if the session number was one in all patients . If not, define the method used to deal with the 
analyzed factor. For example, for patients who underwent multiple endoscopic sessions, how did 
you define the factor "P -GW" and "lithotripsy" when each technique was applied in only one 
session?  
 
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Yes 
 
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.  
 
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 additiona l 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:  
 
Acceptable  
 
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 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 
financi ally 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 organiz ation 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 th e above, write 'I declare that I have no competing interests' below.  
If your reply is yes to any, please give details below.  
 
None  
 
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