Review for 10.1186/s12876-021-01783-9 (2021)

Title: Impact of second forward-view examination on adenoma detection rate during  unsedated
colonoscopy: a randomized controlled trial
Version: 2 Date: 20 Jan 2021
Reviewer's report:
The topic of the study is interesting and meaningful. Improving the detection rate of colon polyps
during colonoscopy is always a hot topic, and has great significance for patients. The second
forward view strategy in right colon is practical and proved effective.
However, there are still some questions to be answered in this paper. In addition, English writing
needs to be improved
Major
1, the novelty of the study was not stated clearly as there exists some similar trials also aiming at
investigating second examination strategy. A single center RCT, in which non typical screening
population were enrolled, does not substantially improve the quality or evidence level compared
to previous studies. The authors should highlight what unique and insightful analysis was
provided by this study in comparison with previous studies.
2, there is a problem of the standard of histopathology examination, because both snare
polypectomy and cold forceps biopsy were performed. From a pathological point of view, SSA/
Ps might be underestimated due to the lack of longitudinal section of the pit on the slides, which
is a common situation resulted from small samples taken from cold forceps biopsy. Thus, as
the gold standard is not uniform, the statistical data, ADR and PDR, may not be accurate. As a
clinical study, it is acceptable but should be listed as a limitation.
3, We don't know whether this method is effective in patients with poor bowel preparation,
because the authors exclude cases with poor bowel preparation but in fact the colonoscope can
be successfully inserted into the ceacum. It seems not necessary to exclude these cases
4, the ADR in this study are much higher than those in many Chinese trials I happen to read,
in which ADR were reported 10-20+%, let alone the population is younger than a guideline-
recommended population. It's good that the ADR far exceeds the guideline recommendation
which was surely obtained by high-level examination, but please give a brief explanation that
why the authors got such a good ADR that is so different from other Chinese trials
5, why not provide AMR in right colon? it is actually a regional tandem procedure. To add an
AMR analysis is meaningful and can strengthen the quality of the study.
6, the detection rate and average number of SSA/Ps in right colon should be provided, because no
matter what new technique is used, it is most valuable to increase the detection rate of SSA/Ps,
a easy-to-miss lesion with higher risk for malignant transformation than conventional adenoam,
in the right colon. Why the authors did not do that? It's no trouble at all to add a table with the
SSA/P statistics.
7, details of the histological characteristics of all polyps should be provided
Minor
1, There are many grammatical and sentence errors in the article, and the level of English
writing is elementary, which is very obvious in discussion section. The English writing needs
a substantial improvement.
2, the average insertion time >6.5 min, were these procedures performed by experienced
endoscopists as described in the paper?
3, why the author defined ascending colon as “proximal”, because the GI community recognize
“ceacum to splenic flexure” as proximal.