The trial conducted by Attilakos et al.1 is a useful example of how one should design a study aiming to address simple and specific questions.
Of course, hardly any study is flaw free and the authors acknowledged most of the weaknesses of their study. However, I feel there is one fundamental flaw that has been underestimated; the operators had no previous experience with the Omnicup before the trial was commenced.
The operators had the opportunity to watch a training video supplied by the company marketing the Omnicup and no further specific training was provided. Moreover, no specialist registrar or consultant in the trial had used the Omnicup in another hospital prior to the study. In comparison, the same operators were very familiar with the standard cups and had used them for a number of years.
I believe that we should be very careful when trying to draw conclusions from this particular study; especially since the Omnicup needs to be applied properly in order to be effective and familiarity with the instrument and its use is of paramount importance. Incorrect application is one of the main reasons for failure to achieve vaginal delivery.2
It is a pity that such a well-designed and honest study underestimated the apparent inexperience of the operators with the instrument the efficacy of which was being assessed. Perhaps, a similar study in a different setting (with experienced operators in both Omnicups and standard cups) would produce more representative results.