Universal Cell Free DNA or Contingent Screening for Trisomy 21: Does It Make a Difference? A Comparative Study with...

Area of Science:

• Prenatal diagnostics
• Genetics
• Maternal-fetal medicine

Background:

• Cell-free DNA (cfDNA) screening is a method for detecting fetal aneuploidies.
• First Trimester (FT) screening combines maternal age, ultrasound, and biochemical markers.
• Optimizing screening strategies can improve efficiency and reduce costs.

Purpose of the Study:

• To compare the detection rate of trisomy 21 between universal cfDNA screening and a contingent screening approach.
• To evaluate the efficiency of a contingent screening model in reducing the number of cfDNA tests performed.

Main Methods:

• Retrospective study at 3 German centers including euploid and trisomy 21 pregnancies.
• First Trimester (FT) risk for trisomy 21 calculated and stratified (high, intermediate, low risk).
• Contingent screening involved cfDNA testing only for intermediate FT risk cases; universal screening examined all cfDNA results.

Main Results:

• Universal cfDNA screening identified all 163 trisomy 21 cases.
• A contingent approach achieved a 98.4% detection rate and a 0.7% false-positive rate.
• Contingent screening required cfDNA testing in only approximately 27% of pregnancies.

Conclusions:

• A contingent screening strategy offers comparable trisomy 21 detection rates to universal cfDNA screening.
• This approach significantly reduces the number of cfDNA tests by 73%, enhancing screening efficiency.
• Contingent screening represents a more resource-conscious method for prenatal aneuploidy detection.