Review for 10.1186/s12876-025-03721-5 (2025)

Title: Operation Sequence of Bidirectional Endoscopy with Topical Anesthesia Affected
Colonoscopy Performance: A Randomized Controlled Trial
Version: 0 Date: 07 Feb 2025
Reviewer:  Anwar Ashraf Abouelnasr
Reviewer's report:
Dear Authors, please address the following points below
-The introduction discusses sedation protocols and their benefits (e.g., EGD-first sequence with
sedation), but it would be helpful to emphasize the novelty and specific relevance of topical
anesthesia in this study. A clearer distinction between sedation and topical anesthesia would
strengthen the rationale for this particular investigation.
-The brief mention of colonic spasms and their impact on procedure quality could be expanded.
Specifically, it could discuss how this influences procedure time, polyp detection rates, and
patient experience—outlining why addressing this issue with optimal sequencing could improve
overall outcomes.
-The description of the topical anesthesia protocol (dyclonine hydrochloride for EGD and
oxybuprocaine hydrochloride for colonoscopy) is clear, but more information could be provided
on how these were applied (e.g., the volume of anesthesia used for each procedure, duration
before procedure start). This detail would allow for a better understanding of potential variations
in anesthesia administration.
-While it is stated that all examinations were performed by senior endoscopists with more than
10 years of experience, the potential for variability in technique among different endoscopists
is not fully addressed. It would be beneficial to mention whether the operators were trained in a
standardized manner for this specific study to reduce bias in the outcomes.
-It would be helpful to include more information on how adverse events were handled during
the study, particularly given that discomfort and potential complications (such as spasms or
incomplete colonoscopy) were identified as key endpoints. Were patients monitored for any
delayed adverse events after the procedure?
-The definition of significant colonic spasm is clear, but further clarification on how these
spasms were visually assessed during the procedure might help. Was there a specific protocol
to determine when spasms were considered significant, and were these assessed by multiple
operators to avoid bias?
-While the study reports the effects of the test sequence on colonic spasms and its correlation
with cecal intubation time and patient comfort, further elaboration on how spasms can affect
other procedural outcomes would be beneficial. For example, the potential influence on polyp
detection rate (PDR) or adenoma miss rate could be explored in more depth, as these factors are
critical for evaluating colonoscopy performance.
-The authors suggest that the relief effect of warm water on colonic spasms may explain
some of the results, but it would be useful to discuss other potential mechanisms behind the
reduced incidence of spasms in the colonoscopy-first group. Could it be related to the patient’s
positioning or a psychological effect of starting with a colonoscopy? Further elaboration on this
would strengthen the interpretation of the results.
-Although the authors acknowledge that the study was conducted by experienced endoscopists,
there could be a more detailed discussion on how this may impact the generalizability of the
findings. The results might differ with less-experienced endoscopists or in different settings,
which could be explored in more detail.
-Although patient discomfort was assessed using the Modified Gloucester Comfort Scale
(MGCS), the discussion could benefit from a deeper dive into how discomfort influenced
overall patient experience and whether it could affect patient compliance with future procedures.
Additionally, a more robust explanation of why the EGD-first sequence didn't result in greater
discomfort could be provided, given that prior studies suggest this might occur.