Changes in the rates of invasive testing after abnormal nuchal translucency (2010 to 2020)

Since the recognition of increased nuchal translucency (NT) as a marker for chromosomal anomalies in the early 1990s, options for follow up testing have evolved. The utilization of non-invasive prenatal testing (NIPT) (2013) and chromosomal microarray (CMA) (2016) have significantly altered this landscape. This study defines the rates of utilization of invasive testing in the pre-NIPT (2010-2013), post NIPT, pre-CMA (2014-2016) and post-CMA (2017-2020) eras to better understand practice patterns and patient decision-making as follow up options evolve. We retrospectively examined invasive procedures performed at our institution from January 2010 to December 2020. We divided the study period into three (2010-2013) (2014-2016) (2017-2020) corresponding to practice shifts in availability and recommended use of NIPT (2013) and CMA (2016) respectively. Our hypothesis was that rates of invasive testing after an abnormal NT would show a decline with the advent of NIPT, but an increase with the uptake of CMA. A total of 788 patients met inclusion criteria in our study, representing those with abnormal NT ≥3.0mm from 2010 to 2020. A significant (p< 0.001) decline in rates of invasive testing was seen in the period of 2014-2016 (post-NIPT, pre-CMA) with 52% of abnormal NTs having invasive procedures versus 37%. In contrast, in post-CMA period (2017-2020), a significant increase was seen as compared to the prior time period, with 137 invasive procedures performed for 259 abnormal NTs (53%). Chorionic villus sampling (CVS) represented most of the invasive testing over all time periods, encompassing, on average 95% of invasive procedures performed over the 10-year study period. This study validates earlier data suggesting a decline in the rates of invasive testing following abnormal NT but suggests that the decline may be reversing in the post-CMA era. Patients are increasingly choosing invasive testing as a means of accessing genetic data not available through non-invasive testing options alone, and these trends are important for providers involved in post-NT counseling.