Reviewer ’s report  
 
Title:  Endometrial scratching in women with implantation failure after a first IVF/ICSI cycle; 
does it lead to a higher live birth rate? The SCRaTCH study: a randomized controlled trial (NTR 
5342)  
 
Version: 0 Date: 30 Nov 2016 
 
Reviewer:  Carolina  Oliveira Nastri  
 
Reviewer’s report:  
 
BMWH -D-16-00322  
 
Endometrial scratching in women with implantation failure after a first IVF/ICSI cycle; does it 
lead to a higher live birth rate? The SCRaTCH study: a randomized controlled trial (NTR 5342)  
 
This is the protocol of a RCT evaluating the effect of endometrial scratching on the reproductive 
outcomes. Overall, it is a very well designed and powered study.  
 
There are other ongoing R CTs evaluating the same intervention. The larger one I have 
knowledge is the PIP study (PMID: 27121007), which includes almost 900 women in the IVF 
arm. The difference would be that in the present study the target population is women 
undergoing the second IVF attempt while in the PIP study woman regardless of the number of 
IVF attempts are eligible. Both are non -blinded studies, which is very appropriate considering 
the very objective nature of the outcomes evaluated.  
 
It is also interesting the estimation o f cumulative pregnancy, even though the scratching is only 
performed once, before the ovarian stimulation. It would be interesting to repeat it just before 
each frozen embryo transfer.  
 
 
I have only two specific comments:  
 
1. The names of the outcomes (e.g. 'live birth rate after the second fresh ART cycle') include a 
reference to the population studied (women in the second IVF cycle with fresh embryo transfer). 
It is a very confusing name, especially for readers that are not familiar with the study design. I t 
would be better if the name of the outcomes did not include the population studied in the trial.  
2. Please, state how the authors have achieved this estimate: 'The difference in live birth rate 
after the second ART cycle is estimated to be 9% between the  patients with and without 
endometrial scratch (39% vs. 30%).'  
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
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.  
 
Unable to assess  
 
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 specify what aspects require further 
assessment in your comments to the editors.  
 
Not relevant to this manuscript  
 
Qualit y of written English  
Please indicate the quality of language in the manuscript:  
 
Acceptable  
 
Declaration of competing interests  
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