Review for 10.1186/s12876-020-01341-9 (2020)

Reviewer ’s report  
 
Title: CO2 or air cholangiography reduces the risk of po st-ERCP cholangitis in patients with 
Bismuth type IV hilar biliary obstruction  
 
Version: 1 Date: 29 Feb 2020  
 
Reviewer: Hemant Goyal  
 
Reviewer's report:  
 
These are important result s for daily practice. However, the language in this manuscript needs to 
extensively revised. For eg. the very first sentence of "background" in the manuscript needs to be 
revised.  
"ERCP procedure" section is very difficult to follow. I did not understand t he use of MRCP 
guidance "during" the ERCP as noted in the 3rd line of of this section.   
 
Are the methods appropriate and well described?  
If not, please specify what is requir ed 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 e xplain 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 recommend additional statistical review  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Not suitable for publication unless extensively edited  
 
 
 
 
 
Declaration of competing interes ts 
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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 financially from the pu blication of this 
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3. Do you hold or are you c urrently applying for any patents  relating to the content of the 
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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?  
 
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below. If your reply is y es to any, please give details below.  
 
I declare that I have no competing interest  
 
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