Review for 10.1186/s12876-019-1053-6 (2019)

Reviewer’s report
Title:  Classification of the Cystic Duct Patterns and Endoscopic Transpapillary Cannulation of the
Gallbladder to Prevent Post-ERCP Cholecystitis
Version: 0 Date: 30 Dec 2018
Reviewer: Young Koog Cheon
Reviewer's report:
General Comments:
PTGBD is commonly performed when cholecystectomy may not be utilized in elderly patients with
multiple comorbidities at a high risk of cholecystectomy. Recently, EUS-guided GB drainage has been
performed as an alternative method of PTGBD. However, EUS-guided GB drainage requires expertise
from endoscopists and the rate of complications is high. If GB drainage may be performed using
natural anatomy in patients who can not go through operations, cholecystitis may be treated effectively
while reducing the complication rate. In this regard, this manuscript is meaningful in which it showed
the anatomy of cystic duct to perform GB drainage through ERCP.
Comments 
1. Selection of the guide wire according to the type of cystic duct, 
2. The overall complication rate by the cannulation of the cystic duct should be described under
Results. Also, the difference in complication rates according to the type should be included. To find the
orifice of the cystic duct, CBD should be injected with sufficient contrast agents.
3. There is a concern that excessive injection of contrast agents into the CBD may cause or exacerbate
cholangitis. What are the authors' opinions on this issue?
4. Cholecystitis may become more severe if GB drainage may not be performed due to the failure of
cystic duct cannulation following the injection of contrast agents to the GB when finding the cystic
duct. A description is required for the actions taken in this case.
5. In Discussion, tips from the authors for successful cannulation according to the type of cystic duct
seems important. Thus, technical tips should be provided under Discussion.
Are the methods appropriate and well described?
If not, please specify what is required 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.
Unable to assess
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 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.
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
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