Changing Face of Invasive Diagnostic Testing in the Era of Cell-Free DNA
Authors: Rosenn Barak , Porat Natalie , Taylor Dyese , Kalberer Meredith , Nelson Zoe , Al-Ibraheemi Zainab 
Published: July 2017

Background Screening for fetal chromosomal anomalies using cell-free DNA (cfDNA) became clinically available in 2012. Since then, it has been widely adopted by providers and pregnant women with or without risk factors for aneuploidy. Concomitantly, the use of invasive diagnostic testing has been steadily declining.

Objective To determine the magnitude of decline and changes in indications for invasive prenatal testing over the past 6 years.

Study Design This was an institutional review board (IRB) approved retrospective cohort study that included women who were referred to our genetic division for consultation between January 2010 and December 2015 and decided to have invasive testing. The total number of patients choosing either option was determined for each year over the entire period and grouped by following indications: advanced maternal age, abnormal maternal serum screening (MS), abnormal ultrasound finding (US), personal or family history of genetic anomaly (FH), and others. Patients, who were advanced maternal age (AMA), were offered noninvasive prenatal screening or chorionic villus sampling (CVS) or amniocentesis in addition to routine nuchal translucency screening. The proportion of AMA patients choosing each of the three options was determined in a 6-month interval over the entire study period. Statistical analysis included logistic regression and chi-square test.

Results While the number of patients receiving genetic counseling at our unit remained unchanged over the study period, the number of invasive procedures declined steadily from 429 amniocentesis (amnio) and 154 CVS in 2010 to 72 amnio and 60 CVS in 2015 (p < 0.001). Over the same period, the distribution of indications for diagnostic testing changed significantly. The proportion of procedures performed due to AMA or MS declined significantly over time (p < 0.001). The proportion of procedures performed for AMA declined at an average yearly rate of 24% (95% CI: 19–29%) and those performed for MS declined at a yearly rate of 13% (95% CI: 6–20%). Over the same period, the proportion of procedures performed due to US, FH, and other indications combined increased (p < 0.001) at an average rate of 45% (95% CI: 36–55%). A total of 5,188 women (61% of the study cohort) had genetic counseling for AMA. The percentage of patients opting for invasive procedures with AMA as the sole indication declined significantly from 38% in 2010 to 2% in 2015 (p < 0.0001) at an average rate of 29% (95% CI: 27–31%) reduction every 6 months. The rate of AMA women opting for cf DNA increased precipitously from 28% in 2012 to 91% in 2015 (p < 0.0001) at an average rate of 66% increase (95% CI: 57–76%) every 6 months.

Conclusion The use of invasive procedures to diagnose chromosomal and genetic anomalies has declined over the past years, primarily due to the availability of cfDNA testing for AMA and abnormal serum screening. The new reality is that fewer women opt for invasive procedures and do so primarily following abnormal ultrasound findings or due to a history of chromosomal or genetic anomalies. Given these trends, it is likely that future generations of maternal–fetal medicine (MFM) subspecialists will not have the opportunity to acquire the necessary skills to perform these procedures, when needed.