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The following is a summary of “Genomic abnormalities in apparently isolated polyhydramnios and the role of confirmed fetal phenotype: a systematic review and meta-analysis,” published in the August 2024 issue of Obstetrics and Gynecology by Tsakmaki et al.

This systematic review and meta-analysis aimed to evaluate the prevalence of genomic abnormalities in pregnancies complicated by apparently isolated hydramnios and to investigate the impact of confirmed fetal phenotypes on these abnormalities. A comprehensive search was conducted in PubMed, Cochrane Library, Google Scholar, and Scopus databases up to May 4, 2024. Eligible studies included observational research published post-2000 in European languages, focusing on genomic outcomes in prenatally-diagnosed isolated polyhydramnios. The primary outcome assessed was the incidence of genomic abnormalities, encompassing chromosomal numerical and structural anomalies and monogenic syndromes identified either prenatally or postnatally. 

Secondary outcomes included the prevalence of chromosomal abnormalities detected by karyotype or chromosomal microarray (CMA), monogenic abnormalities identified via next-generation sequencing (NGS) or clinical genetic evaluation following normal karyotype/CMA results, genetic syndromes in general, and structural abnormalities detected postnatally. Pooled proportions for each outcome were calculated. The meta-analysis incorporated twelve studies with data from 2,561 pregnancies affected by isolated hydramnios. The overall prevalence of genomic anomalies in these cases was 4.5% (95% CI 2.6-7.6), with chromosomal abnormalities accounting for 2.1% (95% CI 1.1-3.7). The incidence of major structural defects identified postnatally was 2.9% (95% CI 1.5-5.4), while in a specific subgroup of four studies involving 14 fetuses, the prevalence of genomic anomalies was significantly higher at 29.8% (95% CI 11.3-58.6). 

Meta-regression analysis revealed a positive correlation between the severity of hydramnios and the rate of genomic anomalies. Additionally, the monogenic anomalies rate was 5.6% (95% CI 2-5; I² = 58%) in the two studies utilizing NGS. The findings suggest that approximately half of the genomic anomalies in cases of isolated polyhydramnios are chromosomal, with the remainder being non-chromosomal. Given these results, CMA and potentially NGS should be considered in managing isolated polyhydramnios, particularly in cases with incomplete fetal phenotype. Further research incorporating NGS and addressing cost-effectiveness is needed to refine these recommendations.

Source: sciencedirect.com/science/article/abs/pii/S2589933324001952