Reviewer ’s report  
 
Title: 3-dimensional versus conventional laparoscopy for benign hyst erectomy: protocol for a  
randomized clinical trial  
 
Version: 1 Date: 12 Nov 2016  
 
Reviewer: Preben Kjölhede  
 
Reviewer's report:  
 
Reviewer comment to manuscript number BMWH -D-16-00043R1: 3 -dimensional versus 
conventional laparoscop y for benign hysterectomy: protocol for a randomized clinical trial  
 
 
 
The task for the reviewer was specifically to evaluate the following four items:  
 
1) Will the study design adequately test the hypothesis?  
 
 
2) Are sufficient details provided to allow application of the work or comparison with 
related analyses: if nor, what is missing?  
 
 
3) Is the planned statistical analysis appropriate?  
 
 
4) Is the writing acceptable?  
 
 
 
Item 1)  Unfortunately the hypothesis is not  directly specified in the text. In the Background the 
authors state that the objective of the study is to compare quality of life and postoperative pain in 
patients randomized to 3D or conventional laparoscopy for benign hysterectomy and secondarily 
asses s per - and postoperative complications, time to return to work and duration of hospital stay. 
I think such objective is trivial and does not describe what the purpose or the hypothesis of the 
study de facto is, namely to determine if 3D laparoscopic hyster ectomy is more favorable for the 
patient and health care system than conventional laparoscopic hysterectomy. The hypothesis is of 
cause, as also stated by the authors in the Discussion, that….. hopefully this trial will help place 
3D laparoscopy in the ran ge of endoscopic approaches for benign hysterectomy.  
 
 
I suggest that the authors re -write the objective in order to emphasize the hypothesis to: The 
objective of the study is to determine if 3D laparoscopy gives better quality of life less 
postoperative pai n and per - and postoperative complications, and shorter stay in hospital and 
time to return to work than conventional laparoscopy for benign hysterectomy.  
 
 
The study design - a RCT - is adequate to test the hypothesis.  
 
 
Item 2)  In most parts the details are  sufficient to allow applications and comparisons. There is 
however a methodological issue that the authors should consider carefully: In the preoperative 
assessment the patient complete the SF -36 questionnaire by herself, this means without help or 
interf erence by the research nurse. At the 6 -weeks follow -up the questionnaire is answered by 
the patient through a telephone interview. I am not sure that it is advisable or even possible to 
compare the two modes of answering since the telephone interview could  imply interference 
from the research nurse in how the patient would answer the questions. Besides, in the "Tables 
for obtaining data in both arms" no information is given about the SF -36 (QoL form) at the 
baseline variable. In general, I think that this t able should be revised and made more easily 
readable and attractive from a layout -point -of-view.  
 
 
In order to assess which mode of laparoscopy that is more favorable in a RCT I think it is 
necessary to use similar and well defined procedures in all other a reas around the surgery, for 
instance the preoperative information and patient education, anesthesia and postoperative care 
including preemptive medication etc. I lack this issue in the manuscript.  
 
 
In the section about Ethical considerations is stated that  information from the Danish 
Hysterectomy Database will be used concerning undesirable medical events. If the authors intent 
to use data from this database I think it should be described clearly in the section Data collection 
and to what extent the databas e will be used.  
 
 
In the primary outcomes is described that pain assessment will be done immediately after return 
to the ward five hours postoperatively. First it may seem unclear why no pain assessments are 
done before this time in the post anesthesia care unit (PACU) and do all patients stay in the 
PACU for approximately five hours as could be interpreted in the text? Pain assessment should 
be related to the analgesics given when and what, and should preferable also be related to lying 
quiet in the bed or d oing physical movements.  
 
 
Major and minor complications are clearly defined as outcome measures, but no information is 
given about how a conversion to laparotomy is categorized - as a major or minor complication or 
is it not seen as a complication?  
 
 
Item 3)  The calculations and assumptions seems ok, but concerning sample size determination it 
seems that the authors have forgotten the withdrawals of consent to participate. The calculated 
number of participants in the study does not include potential withdrawal s and thus the study 
may be underpowered.  
 
 
The authors do not state whether the statistical testing is two -sided. Usually in such studies the 
tests are two -sided, but the authors state that "available evidence suggests that 3D technology is 
at least as goo d as the current technology" i.e. that the result can never be inferior to the 
conventional method and consequently the reader could consider that a one -sided test would be 
more appropriate to use. I therefor suggest that the authors clearly state that the y perform two 
sided statistical tests.  
 
In describing the statistical analyses the author do not specifically describe where the statistical 
analysis plan will be published. It will of cause be of interest to the reader to know this and 
consequently this in formation should be given in the manuscript.  
 
Item 4)  Yes.   
 
 
 
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
No 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Yes 
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Yes 
 
Are you able to assess any statistics in the manuscript or would you recommend an  
additional statistical review?  
If an additional statistical review is recommended, please speci fy what aspects require further 
assessment in your comments to the editors.  
 
I am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Acceptable  
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 f rom an  
organisation that may in any way gain or lose financially from the publication of this  
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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 ap plied for patents relating to the content of the manuscript?  
 
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