Reviewer’s report
Title: 
Cecal Retroflexion is Infrequently Performed in Routine Practice and the
Retroflexed View is of Poor Quality
Version: 
2 
Date: 
03 Feb 2021
Reviewer's report:
Summary: This manuscript discusses the frequency and quality of cecum
retroflexion during screening and surveillance colonoscopies. The study is a 6
week prospective single center observational study from 2016. The study
incorporates video recording technology to review the extent, duration, and
regularity that 17 endoscopists used cecal retroflexion to do a second look at the
right colon. The manuscript finds that cecal retroflexion is used infrequently and,
when performed, is often inadequate. 
Major Comments: 
Comment 1: 
In the current study, 3 polyps were identified in the RV (polyp
detection rate of 8.1%) and all were found before forward-view examination.
However, recent studies of retroflexion in the right colon report higher polyp
detection rate at the right colon (Please see the 3 publications below). For
example, RV detected additional 15.4% of polyps after forward view
examination in Miyamoto et al study. Please discuss why the polyp detection rate
of right colon in this study seems lower than other studies and why RV is of poor
quality here. 
(1) Michopoulos S, Axiaris G, Baxevanis P, Stoupaki M, Gkagkari V,
Leonidakis G, Zampeli E, Sotiropoulou M, Petraki K. Retroflexion, a costless
endoscopic maneuver, increases adenoma detection rate in the ascending colon.
Ann Gastroenterol. 2021;34(1):53-60. doi: 10.20524/aog.2020.0549. Epub 2020
Oct 12. PMID: 33414622; PMCID: PMC7774652.
(2) Miyamoto H, Naoe H, Oda Y, Shono T, Narita R, Oyama S, Hashigo S,
Okuda A, Hasuda K, Tanaka M, Sakurai K, Murakami Y, Sasaki Y. Impact of
retroflexion in the right colon after repeated forward-view examinations. JGH
Open. 2018 Sep 10;2(6):282-287. doi: 10.1002/jgh3.12084. PMID: 30619938;
PMCID: PMC6308076.
(3) Kushnir, Vladimir, Oh, Young, Hollander, Thomas, et al. Impact of
Retroflexion Vs. Second Forward View Examination of the Right Colon on
Adenoma Detection: A Comparison Study. Am J Gastroenterol.
2015;110(3):415-422. doi:10.1038/ajg.2015.21.
Comment 2: What is the range of ADR of the endoscopists involved in the
study? If these endoscopists have a very high ADR despite poor quality RV,
then good RV is probably not important as they are able to detect polyps with
forward view. If they have low ADR, then the low quality RV may reflect low
quality colonoscopy exams. 
Comment 3: Methods Section: The manuscript mentions that the endoscopists
were aware of the recorders and that they had provided informed consent. Were
the endoscopists aware that you were studying retroflexion in the cecum and
right colon? Concern being that perhaps the two endoscopists who retroflexed
every time were aware of the studies aims whereas the others were not. 
Comment 4: Methods Section: Paragraph 1: Please comment on whether any of
the 6 gastroenterologists evaluating the videos were also one of the 17
endoscopists who performed the procedures and were videotaped. If there was
overlap this would introduce bias.
Comment 5: Results, Right Colon Examination section, 2nd paragraph: Of the
two endoscopists who performed CR for every colonoscopy, how often was their
examination full RV to the hepatic flexure? Specifically interested in the rate of
full RV among the practitioners who frequently used CR. Did the majority of full
RV from the entire study come from just the two endoscopists who did CR every
time? 
Comment 6: It has been shown that examination of right colon with either
forward view or retroflexed view yield similar ADR. Please discuss why
infrequent and low quality CR and RV in this study is important.
Minor Comments:
Comment 1: Results Section: Last sentence of first paragraph: "Seven videos per
colonoscopist (119 videos total) were randomly selected for manually review."
Consider changing "manually review" to "manual review:. 
Comment 2: Discussion Section: 2nd paragraph: "Furthermore, when a RV was
obtained via CR, it was often a brief evaluation of the ascending colon with a
careful examination to the level of the hepatic flexure" - Instead of "with a
careful examination" did you mean to say "without a careful examination?"
Publons Reviewer Recognition
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Yes
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
gain 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 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?
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
Reviewer Publication Consent.
 I agree for my report to be made available
under an Open Access Creative Commons CC-BY License (
http://creativecommons.org/licenses/by/4.0
) if this manuscript is accepted for
publication. Any comments that I do not wish to be included in the published
report have been included as confidential comments to the editor, which will not
be published.
If you are not happy for us to publish this report, please contact the
editorial office before completing the review.
If you wish, you can include your
name in your published report. Please note you must decide whether to include
your name at the start of the process and confirm this decision whenever
prompted. If you change your decision later, we will not be able to publish your
name.
I agree to the terms of the CC-BY 4.0 license; please 
do not
 publish my name
with my report. (default)
Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
Yes
Are the methods sufficiently described to allow the study to be repeated?
No
Is the use of statistics and treatment of uncertainties appropriate?
Yes
Is the presentation of the work clear?
Yes
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
Yes
Reviewer’s report
Title: 
Cecal Retroflexion is Infrequently Performed in Routine Practice and the
Retroflexed View is of Poor Quality
Version: 
2 
Date: 
03 Feb 2021
Reviewer's report:
Summary: This manuscript discusses the frequency and quality of cecum
retroflexion during screening and surveillance colonoscopies. The study is a 6
week prospective single center observational study from 2016. The study
incorporates video recording technology to review the extent, duration, and
regularity that 17 endoscopists used cecal retroflexion to do a second look at the
right colon. The manuscript finds that cecal retroflexion is used infrequently and,
when performed, is often inadequate. 
Major Comments: 
Comment 1: 
In the current study, 3 polyps were identified in the RV (polyp
detection rate of 8.1%) and all were found before forward-view examination.
However, recent studies of retroflexion in the right colon report higher polyp
detection rate at the right colon (Please see the 3 publications below). For
example, RV detected additional 15.4% of polyps after forward view
examination in Miyamoto et al study. Please discuss why the polyp detection rate
of right colon in this study seems lower than other studies and why RV is of poor
quality here. 
(1) Michopoulos S, Axiaris G, Baxevanis P, Stoupaki M, Gkagkari V,
Leonidakis G, Zampeli E, Sotiropoulou M, Petraki K. Retroflexion, a costless
endoscopic maneuver, increases adenoma detection rate in the ascending colon.
Ann Gastroenterol. 2021;34(1):53-60. doi: 10.20524/aog.2020.0549. Epub 2020
Oct 12. PMID: 33414622; PMCID: PMC7774652.
(2) Miyamoto H, Naoe H, Oda Y, Shono T, Narita R, Oyama S, Hashigo S,
Okuda A, Hasuda K, Tanaka M, Sakurai K, Murakami Y, Sasaki Y. Impact of
retroflexion in the right colon after repeated forward-view examinations. JGH
Open. 2018 Sep 10;2(6):282-287. doi: 10.1002/jgh3.12084. PMID: 30619938;
PMCID: PMC6308076.
(3) Kushnir, Vladimir, Oh, Young, Hollander, Thomas, et al. Impact of
Retroflexion Vs. Second Forward View Examination of the Right Colon on
Adenoma Detection: A Comparison Study. Am J Gastroenterol.
2015;110(3):415-422. doi:10.1038/ajg.2015.21.
Comment 2: What is the range of ADR of the endoscopists involved in the
study? If these endoscopists have a very high ADR despite poor quality RV,
then good RV is probably not important as they are able to detect polyps with
forward view. If they have low ADR, then the low quality RV may reflect low
quality colonoscopy exams. 
Comment 3: Methods Section: The manuscript mentions that the endoscopists
were aware of the recorders and that they had provided informed consent. Were
the endoscopists aware that you were studying retroflexion in the cecum and
right colon? Concern being that perhaps the two endoscopists who retroflexed
every time were aware of the studies aims whereas the others were not. 
Comment 4: Methods Section: Paragraph 1: Please comment on whether any of
the 6 gastroenterologists evaluating the videos were also one of the 17
endoscopists who performed the procedures and were videotaped. If there was
overlap this would introduce bias.
Comment 5: Results, Right Colon Examination section, 2nd paragraph: Of the
two endoscopists who performed CR for every colonoscopy, how often was their
examination full RV to the hepatic flexure? Specifically interested in the rate of
full RV among the practitioners who frequently used CR. Did the majority of full
RV from the entire study come from just the two endoscopists who did CR every
time? 
Comment 6: It has been shown that examination of right colon with either
forward view or retroflexed view yield similar ADR. Please discuss why
infrequent and low quality CR and RV in this study is important.
Minor Comments:
Comment 1: Results Section: Last sentence of first paragraph: "Seven videos per
colonoscopist (119 videos total) were randomly selected for manually review."
Consider changing "manually review" to "manual review:. 
Comment 2: Discussion Section: 2nd paragraph: "Furthermore, when a RV was
obtained via CR, it was often a brief evaluation of the ascending colon with a
careful examination to the level of the hepatic flexure" - Instead of "with a
careful examination" did you mean to say "without a careful examination?"
Publons Reviewer Recognition
. Springer Nature can send verification of this
review directly to Publons (a subsidiary of Clarivate Analytics). If you would
like to take advantage of this service, please click on the “Yes” option below.
Your name, email address, title of the reviewed manuscript, name of the journal,
and date of your review submission (the “Review Data”) will then be transmitted
to Publons after the final decision on the manuscript has been made. If you have
already registered at Publons, they will notify you of the receipt of this review
and update your profile 
as per your settings and their policy. If you are not
registered with Publons, you will receive an email from them asking you to
register in order for them to be able to recognize your review on your new
profile page. Publons may use the Review Data to generate derivative metadata
for the benefit of Publons and you as a reviewer, carefully considering the
sensitivity of such information. For example, Publons may verify your record as
a reviewer by updating your profile published on its webservice if you have
registered for such service or help editors to identify candidate reviewers. Please
find the details of processing in Publons’ privacy policy
https://publons.com/about/terms
Yes
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
gain 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 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?
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
Reviewer Publication Consent.
 I agree for my report to be made available
under an Open Access Creative Commons CC-BY License (
http://creativecommons.org/licenses/by/4.0
) if this manuscript is accepted for
publication. Any comments that I do not wish to be included in the published
report have been included as confidential comments to the editor, which will not
be published.
If you are not happy for us to publish this report, please contact the
editorial office before completing the review.
If you wish, you can include your
name in your published report. Please note you must decide whether to include
your name at the start of the process and confirm this decision whenever
prompted. If you change your decision later, we will not be able to publish your
name.
I agree to the terms of the CC-BY 4.0 license; please 
do not
 publish my name
with my report. (default)
Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
Yes
Are the methods sufficiently described to allow the study to be repeated?
No
Is the use of statistics and treatment of uncertainties appropriate?
Yes
Is the presentation of the work clear?
Yes
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
Yes
Please review this paper.
user
Reviewer’s report
Title: 
Cecal Retroflexion is Infrequently Performed in Routine Practice and the
Retroflexed View is of Poor Quality
Version: 
2 
Date: 
03 Feb 2021
Reviewer's report:
Summary: This manuscript discusses the frequency and quality of cecum
retroflexion during screening and surveillance colonoscopies. The study is a 6
week prospective single center observational study from 2016. The study
incorporates video recording technology to review the extent, duration, and
regularity that 17 endoscopists used cecal retroflexion to do a second look at the
right colon. The manuscript finds that cecal retroflexion is used infrequently and,
when performed, is often inadequate. 
Major Comments: 
Comment 1: 
In the current study, 3 polyps were identified in the RV (polyp
detection rate of 8.1%) and all were found before forward-view examination.
However, recent studies of retroflexion in the right colon report higher polyp
detection rate at the right colon (Please see the 3 publications below). For
example, RV detected additional 15.4% of polyps after forward view
examination in Miyamoto et al study. Please discuss why the polyp detection rate
of right colon in this study seems lower than other studies and why RV is of poor
quality here. 
(1) Michopoulos S, Axiaris G, Baxevanis P, Stoupaki M, Gkagkari V,
Leonidakis G, Zampeli E, Sotiropoulou M, Petraki K. Retroflexion, a costless
endoscopic maneuver, increases adenoma detection rate in the ascending colon.
Ann Gastroenterol. 2021;34(1):53-60. doi: 10.20524/aog.2020.0549. Epub 2020
Oct 12. PMID: 33414622; PMCID: PMC7774652.
(2) Miyamoto H, Naoe H, Oda Y, Shono T, Narita R, Oyama S, Hashigo S,
Okuda A, Hasuda K, Tanaka M, Sakurai K, Murakami Y, Sasaki Y. Impact of
retroflexion in the right colon after repeated forward-view examinations. JGH
Open. 2018 Sep 10;2(6):282-287. doi: 10.1002/jgh3.12084. PMID: 30619938;
PMCID: PMC6308076.
(3) Kushnir, Vladimir, Oh, Young, Hollander, Thomas, et al. Impact of
Retroflexion Vs. Second Forward View Examination of the Right Colon on
Adenoma Detection: A Comparison Study. Am J Gastroenterol.
2015;110(3):415-422. doi:10.1038/ajg.2015.21.
Comment 2: What is the range of ADR of the endoscopists involved in the
study? If these endoscopists have a very high ADR despite poor quality RV,
then good RV is probably not important as they are able to detect polyps with
forward view. If they have low ADR, then the low quality RV may reflect low
quality colonoscopy exams. 
Comment 3: Methods Section: The manuscript mentions that the endoscopists
were aware of the recorders and that they had provided informed consent. Were
the endoscopists aware that you were studying retroflexion in the cecum and
right colon? Concern being that perhaps the two endoscopists who retroflexed
every time were aware of the studies aims whereas the others were not. 
Comment 4: Methods Section: Paragraph 1: Please comment on whether any of
the 6 gastroenterologists evaluating the videos were also one of the 17
endoscopists who performed the procedures and were videotaped. If there was
overlap this would introduce bias.
Comment 5: Results, Right Colon Examination section, 2nd paragraph: Of the
two endoscopists who performed CR for every colonoscopy, how often was their
examination full RV to the hepatic flexure? Specifically interested in the rate of
full RV among the practitioners who frequently used CR. Did the majority of full
RV from the entire study come from just the two endoscopists who did CR every
time? 
Comment 6: It has been shown that examination of right colon with either
forward view or retroflexed view yield similar ADR. Please discuss why
infrequent and low quality CR and RV in this study is important.
Minor Comments:
Comment 1: Results Section: Last sentence of first paragraph: "Seven videos per
colonoscopist (119 videos total) were randomly selected for manually review."
Consider changing "manually review" to "manual review:. 
Comment 2: Discussion Section: 2nd paragraph: "Furthermore, when a RV was
obtained via CR, it was often a brief evaluation of the ascending colon with a
careful examination to the level of the hepatic flexure" - Instead of "with a
careful examination" did you mean to say "without a careful examination?"
Publons Reviewer Recognition
. Springer Nature can send verification of this
review directly to Publons (a subsidiary of Clarivate Analytics). If you would
like to take advantage of this service, please click on the “Yes” option below.
Your name, email address, title of the reviewed manuscript, name of the journal,
and date of your review submission (the “Review Data”) will then be transmitted
to Publons after the final decision on the manuscript has been made. If you have
already registered at Publons, they will notify you of the receipt of this review
and update your profile 
as per your settings and their policy. If you are not
registered with Publons, you will receive an email from them asking you to
register in order for them to be able to recognize your review on your new
profile page. Publons may use the Review Data to generate derivative metadata
for the benefit of Publons and you as a reviewer, carefully considering the
sensitivity of such information. For example, Publons may verify your record as
a reviewer by updating your profile published on its webservice if you have
registered for such service or help editors to identify candidate reviewers. Please
find the details of processing in Publons’ privacy policy
https://publons.com/about/terms
Yes
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
gain 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 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?
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
Reviewer Publication Consent.
 I agree for my report to be made available
under an Open Access Creative Commons CC-BY License (
http://creativecommons.org/licenses/by/4.0
) if this manuscript is accepted for
publication. Any comments that I do not wish to be included in the published
report have been included as confidential comments to the editor, which will not
be published.
If you are not happy for us to publish this report, please contact the
editorial office before completing the review.
If you wish, you can include your
name in your published report. Please note you must decide whether to include
your name at the start of the process and confirm this decision whenever
prompted. If you change your decision later, we will not be able to publish your
name.
I agree to the terms of the CC-BY 4.0 license; please 
do not
 publish my name
with my report. (default)
Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
Yes
Are the methods sufficiently described to allow the study to be repeated?
No
Is the use of statistics and treatment of uncertainties appropriate?
Yes
Is the presentation of the work clear?
Yes
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
Yes
assistant