P734: Implementing a prenatal-specific reference markedly improves call quality and reduces repeat testing for clinical CMA

In 2016, ACOG and SMFM issued joint guidelines recommending chromosomal microarray (CMA) as a first-tier genetic test for prenatal cases undergoing invasive procedures with major structural abnormalities identified by fetal ultrasound and instances of fetal death or stillbirth. Since then, the UCLA cytogenetics laboratory has routinely performed prenatal testing on chorionic villus sampling (CVS), amniotic fluid (AF), and products of conception (POC) specimens, with an annual volume of approximately 400 tests per annum.