Review for 10.1186/s12876-021-01689-6 (2021)

Reviewer’s report
Title: 
Utility and safety of a new uneven double-lumen sphincterotome in cases
of difficult biliary cannulation
Version: 
0 
Date: 
29 Oct 2020
Reviewer's report:
This is a retrospective study wherein a new double lumen sphincterotome was
compared to the conventional technique for pancreatic guide wire (PGW)
placement in patients where double wire technique was required to achieve
biliary canulation during ERCP. The study is interesting however there are a few
areas which need clarification:
1. Methods: 
-As it is a retrospective study it is important to understand how the data of the
patient is stored and recorded over 7 years. Was the data 
obtained from review of
patient procedural videos or was it from an electronic database.
-The authors have not mentioned how they addressed confounding. A propensity
score matching may have been a good way to control for confounding
2. Results:
-~ 40 - 50% of the procedures were done by trainees in both the groups. Was
there a difference in the canulation time and/0r complication rates between Non
trainee and trainee when using the new double lumen sphincterotome
- Is there a difference in the cost between the new sphincterotome and the
conventional one - if yes - then how much
3. Discussion:
- There is a 10 min difference in procedure time between the two
sphincterotomes. How would the authors explain the clinical benefit of this
difference in the management of patients. 
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Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
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