Reply: Fruit and fetal brain MRI--the cherry-picking approach to systematic reviews.

Abstract

We thank Dr Paladini for his interest in our article. The literature search for our systematic review ended in 2012, as described in the methods, explaining why his more recent paper was not included. With regard to his first observation, we believe that the external validity of the results of his series may be limited by patient selection due to referral bias, and by the fact that a single operator performed and interpreted all ultrasound examinations. In fact, Dr Paladini states that fetal magnetic resonance imaging (MRI) was offered ‘only if the expert neurosonologist deems it necessary or advisable’, and this resulted in 16% of cases undergoing MRI1. However, the specific criteria that make a fetal brain MRI either necessary or advisable are not reported. For instance, an ‘inconclusive or uncertain finding’ on neurosonography for one sonographer could be definitively conclusive and certain for another sonographer. There are no standard criteria in the literature with which to identify accurately and reproducibly pregnancies that may benefit from fetal brain MRI. With regard to the second comment, experts in fetal medicine performed the studies included in our review, in referral centers. We described in detail the heterogeneity in protocols used for ultrasound examinations, but this is by no means the only source of heterogeneity. Therefore, we are unable to limit the systematic review to apples or oranges, as we do not have an objective way to make this distinction, and we would be simply cherry-picking instead. As for the definition of ‘advanced neurosonographic assessment by an expert fetal neurologist’, which is without doubt what Dr Paladini personally performs, we would like to reassure readers that, in reality, the Italian national guidelines suggest more modestly that it is not justified to perform fetal MRI ‘without first obtaining an ultrasound evaluation done by an expert operator’2. The final point made by Dr Paladini is that an expert in fetal medicine should indicate MRI; with this we concur fully. We believe that the advantage of a systematic review is to try to report objectively what is known and unknown in the literature. To this end, our systematic review illustrates accurately the limitations of the literature. A. C. Rossi† and F. Prefumo*‡ †Department of Obstetrics and Gynaecology, Ospedale della Murgia, Bari, Italy; ‡Department of Obstetrics and Gynaecology, University of Brescia, Brescia, Italy *Correspondence. (e-mail: [email protected])