Review for 10.1186/s12876-020-01361-5 (2020)

Reviewer ’s report  
 
Title: Cap-assisted endoscopy increases ampulla of Vater visualization in high -risk patients   
 
Version: 0 Date: 01 Apr 2020  
 
Reviewer's report:  
 
The authors here performed a prospective controlled tandem study comparing standard forward 
viewing endoscopy (FVE) with cap -assisted endoscopy (CAE) in visualising the ampulla of 
Vate r. There are some issues concerned in the manuscript that need to be rectified before it can 
be accepted for publication.  
 
Comments:  
1. The duodenal examination time for AV visualization needs to be defined clearly. The 
calculation of the mean examination time should be explained. Ideally, the calculation of the 
mean examination time should include only the cohort with complete AV visualization in the 
FVE arm with negative findings. By doing so, the comparison of the mean examination between 
both arms will be more meaningful. However, some would still argue that more time would have 
been spent during the 1st examination (FVE) for duodenal inspection other than AV 
visualization.  
2. Was intra -observer agreement calculated? If not, please remove "intra -observer " from 
the text (Page 8, 4th paragraph, 2nd sentence - Under Methodology / Sample Size)  
3. Who made the decision whether the AV visualisation to be complete, partial or not 
visualized? Was it determined during the endoscopy (by the resident and the supervi sor) or 
during the review of the video recording (by the independent "blinded" assessor)? Please state.  
4. The use of abbreviation should be consistent throughout the text. Once abbreviated, the 
abbreviation should be used subsequently. For example, ampull a of Vater was abbreviated as AV 
but in the subsequent text, the non -abbreviated term was still used. Other examples were 
forward -viewing endoscope (FVE). Please review the text again and rectify this.  
5. Under Result / Population Description (Page 9, 1st paragraph, 5th sentence): instead of 
giving the number for Spigelman stage II, it will be better to state the figure for stage II and 
above (42+12+1 = 64%) to highlight that more patients with advanced disease were included in 
this study  
6. Under Result / Use of Sedatives and Scopolamine (Page 9, 3rd paragraph, 1st 
sentence): "Additional doses of …. 1.9+/ -0.5mg of midazolam in 24.5% of patients…" The word 
"midazolam" was missed in the text.  
7. Under Discussion (Page 12, 3rd paragraph, 2nd sen tence): The meaning was not clear. 
Please state how the ERCP endoscopist perform the exam? Was it by using side -viewing 
endoscope or forward -viewing endoscope?  
8. There were some errors in the number which need to be rectified:  
* Table 4 (under FVE): AV pa rtially visualised and not given scopolamine should be 36 
(72.0%)  
* Table 4 (under CAE): AV completely visualized and given scopolamine should be 22 
(22.2%)  
* Table 4 (under CAE): AV completely visualized and not given scopolamine should be 
77 (77.8%)  
9. There were some grammatical and sentence construction issues. I suggest to revise the 
sentences to the following:  
* Page 4 (2nd paragraph): Complete visualisation of the ampulla of Vater (AV) during 
screening upper GI endoscopy is important as it allows det ection of early ampullary neoplasia. 
Limitations of the conventional esophagogastroduodenoscopy (EGD) using forward -viewing 
endoscope in visualising the AV are mainly due to the tangential position of the AV, presence of 
anatomical variants in certain pati ents such as overlying duodenal folds or periampullary 
diverticulum and inability to achieve complete straightening in certain cases.  
* Page 4 (4th paragraph, 2nd sentence): One technique to improve visualisation rate is to 
straighten the scope by withdra wing it when the tip of the endoscope reach the proximal level of 
the descending duodenum.  
* Page 5 (1st paragraph, 3rd sentence): In selected patients in which AV had been missed 
by forward -viewing endoscopy, Choi et al. showed that a complete AV visuali sation rate of up to 
91.3% can be achieved in this group of patients when re -examined with cap -assisted endoscopy 
(CAE).  
* Page 6 (2nd paragraph, 1st sentence): The inclusion criteria were age &gt; 18 years old 
and those scheduled for EGD with the intenti on of examining the AV.  
* Page 6 (3rd paragraph, 2nd sentence): The procedure was performed by a GI 
endoscopy resident under the supervision of a senior endoscopist.  
* Page 6 (3rd paragraph, 4th sentence): Olympus gastroscope (GIF -H180J; Olympus 
Optical Co., Ltd., Brazil) and duodenoscope (TJF -160VR; Olympus Optical Co., Ltd., Brazil) 
were used in this study.  
 
Note: the page and paragraph reference numbers as quoted here were based on the manuscript 
draft in pdf format prepared for the reviewer  
 
 
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.  
 
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 t he 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:  
 
Needs som e language corrections before being published  
 
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 financially from the publication of this  
manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares in an organisation that may in any way gai n or lose  
financially 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 salar y 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?  
 
If you can answer no to all of the above, write 'I declare that I have no competing interests' 
below.  If your reply is yes to any, please give details below.  
 
I declare that I have no competing interests  
 
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