Response to commentary by Goedele M.A. Beckers.
We thank the commentator for their kind comments on our paper on fetal megacystis, which we believe to be the first systematic review of this topic. The inclusion of case reports in systematic reviews is contentious. Some systematic reviews have by necessity had to include case reports because these represent the only available data, but single case reports tend not to be included in systematic reviews that can incorporate case series or higher levels of evidence [1,2]. In our study design, we followed the advice of systematic review experts who suggest first asking the question “Will case reports provide valid and useful information to address the key questions in our study?” We considered that bias from inclusion of single case reports would skew our data, and therefore conclusions [3]. The aim of our study was not to review specific prenatal diagnoses but to address the spectrum of fetal megacystis. Conditions such as megacystisemicrocoloneintestinal hypoperistalsis syndrome (MMIHS) are the subject of reviews in their own right [4e7]. The OEIS complex (omphalocele, exstrophy, imperforate anus, spinal defects) is rarely associated with megacystis; we identified only two potential cases [8,9] from among more than 1000 cases of fetal megacystis. We acknowledge that many of the manuscripts included in our review were from Western Europe but others were from the United States [10], Brazil [11], Saudi Arabia [12], India [13], and Australia [14]. We reject the suggestion that the distribution of countries represented was due to “lack of access to other databases.” Scopus, PubMed, MEDLINE, and Google Scholar are all major internationally recognized databases. Finally, prenatal karyotyping has an established role in the work-up of fetal megacystis [15]. Our review indicates a relatively high incidence of trisomies among other chromosomal anomalies.