Review for 10.1186/s12876-022-02581-7 (2022)

Title: Effect of posture on anorectal manometric measurements in female patients with fecal
incontinence and rectoanal intussusception
Version: 3 Date: 22 Sep 2022
Reviewer's report:
The authors performed very interesting study and have generated a lot of data. But somehow the
data is not presented in a structured and coherent way in the Results. It looks as if the authors
did not exactly know what they want to prove or how to use the data to reach their aim (which
is very clear and straightforward). This is also visible in the Discussion, where little explanation
of what they see, and very little clinical relevance is discussed. It is a pity, as the amount of data
they present in tables, and information which they could pull out of the data, is really impressive.
Introduction: The introduction is clearly written, aims clearly formulated.
Minor points:
1. The reason(s), why would one decide to perform anorectal manometry in erect position is
unclear. I assume that authors aimed to mimic the ‘’real condition’’ when fecal incontinence
happens? However, fecal incontinence happen also in sleep (i.e. horizontal position) and also
when sitting. So, I would like to know what is the clinical relevance of anorectal manometry
performed in erect position.
2. I am not sure if the information that some parts of the data in this study were reported in the
non-English literature should be placed at the end of Introduction. I woule either incorporate it
in the introduction (‘’Preliminary data showed that…./ We have already showed that… [10]) or
maybe even better in the Methods.
Methods
1. I see that the measurements were performed during a period of 6 years. Was during these 6
years the same standard protocol followed?
2. Anorectal manometry is known to be quite a sensitive technique, where for instance
suboptimal or different positioning of the catheter can influence measurements. Therefore, it
requires a lot of experience in performance and in interpretation of the outcomes. How many
different investigators (doctors? or specialized nurses?) performed the anorectal manometry and
interpreted the outcomes?
3. I am intrigued by the definition of the anal canal length (as this is always what I am struggling
with when defining the length in our study) and I must say, I do not understand the definition
the authors provide (i.e. ‘’The anal canal length was determined as the difference between
the measurements at the beginning of the resting pressure rise and the end of the pressure
fall’’). Could the authors explain this definition using a simple, schematic illustration? Could
the authors also explain whether it is their internal, validated definition (of their institute) or did
they take it over from some other studies? If the last one, then they should provide the reference.
4. What was the speed of pulling the transducer through the anal canal? Are the authors aware
of the possible bias of an accidental activation of the anal external sphincter continence reflex,
which has its receptors in the anal mucosa by the pull through procedure?
Results
Minor points:
1. I would appreciate if the authors distinguished at least two paragraphs in the Results, including
‘’Patients’ characteristic’’ and for instance ‘’Comparison of anorectal physiology in different
positions’’, to easily guide the reader through their results.
2. Authors provide the numbers of patients but to get the idea of relative magnitude, it would
be wise to provide the percentage (for instance the % of patients who had and had not the
circumferential rectoanal intussusception).
3. What a figure or a table shows is not a result – this information is normally provided in the
title of a table or legends to the figure. Therefore sentences such as ‘’Table 3 shows the effects
of posture on physiological measurements in the 80 FI patients’’ or “Table 4 shows the effects
of posture on physiological measurements in the CRAI and non-CRAI groups”, etc.  should be
replaced by subtitles of paragraphs.
4. Figure 3: the Y-axes should be described as ‘’Changes in maximum squeeze pressure’’.
Major points:
1. I think the Results need to be rewritten in such a way, that the most relevant and important
data is translated to results, and that the authors specifically point out what did they find, instead
of telling the reader where can he/she find the data. Specifically, normally, the tables and the
text included in the main body of the article should be written in such a way that they can be
understood independently of each other. Therefore, I find the first sentence ‘’The characteristics
of the study participants are shown in Table 1.’’ too minimalistic, and I would expect to find
some basic information about the patients in the main body. Also ‘’The image findings and
physiological measurements are shown in Table 2.’’ – the reader needs to be guided through the
most important findings. At this moment it feels like ‘’suit yourself and choice what you find
relevant for our hypothesis by yourself’’. The results are so short, that it should not be a problem
to dedicate some more space to describe the most important findings, which are directly linked
to the aim of this study.
Discussion
1. Authors say that their study demonstrated that squeeze pressure in female patients with FI
and CRAI was significantly lower in the erect position than in the left-lateral position (although
this finding was not true of those with non-CRAI). What is the clinical relevance of this
finding? Ideally, it would be great to show whether this finding has any association with fecal
incontinence. For this however, test performed in continent patients would be needed, as the
squeeze pressure is crucial only in case of urge incontinence. Therefore, I would like to ask the
authors to analyze association between different forms of fecal incontinence and the squeeze
pressure (both: measured in laying and standing position).
2. The authors say that their findings ‘’might provide additional information on FI development
in the erect position’’ – what do they authors mean with ‘’development’’ – etiology? Their
patients have already fecal incontinence. Or do the authors mean that the erect position increases
the chance of fecal incontinence?
3. It would be wise to discuss the statistically obtained significance with clinical relevance.