The Application of Late Amniocentesis: A Retrospective Study in a Tertiary Fetal Medicine Center in China

Abstract Background: To assess the indications and complications of late amniocentesis, and the advantage of advanced genetic test results in a tertiary university fetal medical medicine unit.Methods: In this retrospective study, women that underwent amniocentesis at 24+0 to 39+4 weeks, between January 2014 and December 2019, were recruited. Indications, complications, genetic test results, and pregnancy outcomes were reported for each pregnancy. Information was retrieved from patient medical records, checked by research staff, and analyzed. Results: Of the 1277 women (1311 fetuses) included, late detected sonographic abnormalities (86.2%) were the most common indication. The overall preterm birth and intrauterine demise rate were 2.6% and 1.2%, respectively, after amniocentesis. Sixty-six fetuses with aneuploidy (5.1%) and sixty-seven fetuses with pathogenic copy number variations (5.1%) were identified by chromosomal microarray analysis. One pathogenic copy number variation was detected by whole-exome sequencing. The maximal diagnostic yield (36.1%) was in the subgroup of fetuses with the abnormal noninvasive prenatal test, following by multiple abnormalities (23.8%). And 35.8% of the pregnancies were finally terminated.Conclusions: Due to the high detection rates of advanced genetic technologies and safety of the invasive procedure, it is reasonable to recommend late amniocentesis as an effective and credible method to detect late-onset fetal abnormalities. However, chromosomal microarray and whole-exome sequencing may result in uncertain results like variants of uncertain significance. Therefore, comprehensive genetic counseling is necessary.