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: 
1 
Date: 
15 Feb 2021
Reviewer's report:
Very much impressed with the sincere and honest responses by the authors. The
outcomes - biliary cannulation success and rate of PEP are not changed with
Magictome compared to conventional pancreatic guidewire method. Indirect
reduction of sedation and radiation risk by reducing the PD to CBD cannulation
time is the significant clinical outcome by Magictome. The authors can
emphasize the same in conclusions of the study if possible.
A few modifications if made to the manuscript, it would be better. Here are the
suggestions-
1. Limitations of study - A paragraph has been added to the manuscript at the
end citing low numbers, retrospective nature, single centre and the need to
replicate in larger study sample. That is nice. If possible the same factors can be
mentioned at the relevant areas in discussion where they might have affected
results - cannulation success, rate of PEP etc.
2. Future areas of research - comparing magictome with regular sphincterotome,
not using historical controls, providing proper SOC PEP prophylactic measures
taken - can be added if possible.
3. For comment 4, the authors have confirmed that second guidewire could be
passed easily in the same way as the axis of the first guidewire. If possible they
can provide fluoroscopic pictures demonstrating the same instead of or along
with graphic picture.
4. The responses for comments 5 and 6 are contradictory. 
"more pancreatic duct
stent placements" and "lower rate of PD stenting" for the same numbers 22.7%
in magictome group and 24% in conventional group. The authors can make it
more clear . 
Maybe JGES 2018 guidelines(Ryozawa etal) not endorsing PD
stenting for every case and national health insurance not covering PD stenting
may be added as limitations.
5. For comment 7, pancreatic duct guidewire placement time affecting PEP - A
multicentre French trial(ClinicalTrials.gov Identifier: NCT03582540) comparing
early vs delayed (>10min) double guidewire technique did not publish data as
the outcomes are not that great. And also your unpublished data may not serve as
good evidence. Please mention if any strong evidence is there or else mention the
same limitation in the manuscript.
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