467: Trends in volume of nuchal translucency scans for twin pregnancies since introduction of cell-free DNA

Abstract

While cell-free DNA (cfDNA) screening has become increasingly used in singletons, to date ACOG and SMFM have not endorsed cfDNA screening in twins due to lack of adequate validation. Nuchal translucency (NT) screening has advantages in twins. NT and CRL measurements performed by approximately 9000 credentialed U.S. providers as part of serum combined aneuploidy screening are submitted to the NT Quality Review (NTQR) program for ongoing quality monitoring. The objectives were to assess changes in volume of twin NT scans reported to the NTQR program since introduction of cfDNA screening in 2011 and to compare the change in twin NT volume to the change observed in singletons. The total volume of NT scans submitted to NTQR annually from 1/2012 thru 12/2018 for singleton and twin pregnancies was reviewed. For each year, the average number of NT scans per month and variation between years was evaluated using ANOVA and post-hoc paired t-tests. There were 3,558,594 singleton NT scans (average 509,370 +38776 per year) and 80,255 (average 11,465+1635 per year) twin scans reported over the study period. Annual NT volume showed a downward trend (Table, Figure). For singletons, there was little variation in the annual NT volume between 2012 to 2015, whereas annual NT volume decreased significantly between 2016 and 2018 (p< .00001). For twins, there has been a steady decline since 2012, dropping sharply beginning in 2015. Since 2012, annual NT volume for singletons has decreased by 19.6%, and for twins by 35.6%. There has been a 36% reduction in the number of NT scans performed annually by NTQR credentialed providers as part of first trimester combined screening for twins since the introduction of cfDNA screening. This is considerably higher than the 20% reduction observed in singletons. While these data provide some insight into national trends in aneuploidy screening in the United States, further exploration may provide additional information regarding how NT and cfDNA assessment is being used in twins in the era of cfDNA screening.View Large Image Figure ViewerDownload Hi-res image Download (PPT)