Review for 10.1186/s12876-022-02607-0 (2022)

Title: Value of abdominal ultrasonography in predicting intestinal resection for premature
infants with necrotizing enterocolitis
Version: 2 Date: 07 Sep 2022
Reviewer's report:
This is a retrospective study evaluating the use of abdominal ultrasound in infants with surgical
NEC to predict need for intestinal resection. There is a need to earlier identify and predict the
severity of NEC and need for additional interventions, where the author proposes abdominal US
to have a role. Strengths include the large number of infants with surgically-managed NEC in
multiple centers, as well as the detailed parameters measured by AUS over serial timepoints, and
the comparison of abdominal US to radiography. Some areas of the manuscript need revisions
as well as some clarifications, as detailed below.
Major Comments
I recommend changing the odds ratios so that the numerator includes the exposure in the bowel
resection group, given that bowel resection is your primary outcome which will allow the reader
to review and interpret the results more easily. For example, OR of needing bowel resection is
4.1 for thick to thin transformation on AUS (compared to 0.23, which suggests on first glance
that the exposure is less likely associated with the outcome of intestinal resection).
Given the different management strategies in NEC, can you clarify the potential surgical
interventions in the group that is not needing intestinal resection and why they are having a
laparotomy?
Line 180: Enteral feeding history is discussed that the groups were comparable but I do not see
this as a variable in the table or discussed in the results. If any feeding data is available, would
recommend adding it to the table/results section.
Discussion: Overall, the discussion needs some reorganization/clarifications to improve
readability for the reader, and also some areas of repetition that can be condensed. Some specifics
of certain referenced studies could be expanded upon to enhance the discussion.
Minor Comments
Abstract, Objective line 38: Recommend being more specific – for example, instead of “its”
would state “abdominal ultrasound” and “predict” rather than efficiency.
Your abstract and study design mentions you reviewed laboratory data but I do not see any of
this presented in results. Can you clarify or remove?
Line 104: Clarify timing of abdominal US – was the day of admission on newborn day/day of
life 0 or was this the day of diagnosis of NEC?
Line 114: Clarify who performed the bedside ultrasound – was it a trained sonographer,
neonatologist, other, etc.
Study design: lines 125-128: spell out ultrasound abbreviations
Lines 216-219: Clarify these lines, would caution against stating that bowel “should be” resected
given retrospective nature of the study., but overall I am unclear if you are re-stating some of
the results or drawing conclusions. Consider “diagnosed at an advanced stage ultimately need
bowel resection. In our study, bowel resection occurred in approximately half of the patients
investigated.”
Line 220: Suggest specifying the current bowel resection rates “in infants with NEC requiring
surgical management” as I think this is important to your next statement regarding why this may
be the case, perhaps attempting earlier laparotomy for other related (but non-bowel resection)
interventions.
Discussion: line 222: can you elaborate on “early stage” surgical management? Is this soon after
diagnosis or what prompts surgical intervention at the included institutions?
Discussion – second paragraph: Suggest reorganization and some clarification. Consider stating
the problem (ie intestinal loss and no predictors that exist (lines 224-227) and study design (lines
227-230) earlier in the paragraph and before you further discuss your results and comparison to
other literature). Consider elaborating more on why intestinal loss should be avoided (other than
the acute complications of bowel ischemia) and consider adding some specifics on how earlier
identification of intestinal ischemia helps the infant and/or surgeon.
Lines 240-241: suggest more discussion of this meta-analysis and what AUS parameters are
predictive of death and/or need for surgery and discuss how this compares to your findings.
Lines 241-248: consider moving this section earlier – for example after first sentence in line 231.
Line 290: Consider adding what the variables have been evaluated for: Surgical NEC/death/etc.
Conclusion (both in manuscript and abstract): Would caution against some of the language
used here. Your study does support that AUS should be considered in determining need for
surgical management, likely in conjunction with other clinical factors (but not necessarily that
surgeons should rely on AUS primarily). A future prospective study with more controlled
imaging measurements would be useful.
Table 1: Is this the gestational age at diagnosis of NEC or overall? The median gestational age of
~34 and 33 weeks seems high for infants in your cohort. Would be interesting to note and discuss
this in the discussion and is potentially a limitation to generalize this to other populations.
Be consistent with capitalization in tables.
Table 3 Title: Would consider being more specific, for example using “bowel resection” instead
of “prognosis.