The advantages of using triple-marker screening for chromosomal abnormalities

Area of Science:

• Prenatal diagnostics
• Genetics
• Obstetrics

Background:

• Maternal serum screening is crucial for detecting fetal chromosomal abnormalities.
• Traditional screening methods often rely on maternal age and limited biochemical markers.
• Evaluating novel marker combinations is essential for improving diagnostic accuracy.

Purpose of the Study:

• To assess the diagnostic utility of triple-marker serum screening for chromosomal abnormalities.
• To determine the effectiveness of adding unconjugated estriol to existing screening protocols.
• To re-evaluate the criteria for offering amniocentesis in prenatal care.

Main Methods:

• Analysis of 10,605 maternal serum samples from 15-22 weeks gestation.
• Triple-marker screening included alpha-fetoprotein, human chorionic gonadotropin, and unconjugated estriol with maternal age.
• Screen-positive criteria defined for trisomy 21 (risk ≥ 1:270) and trisomy 18 (low marker levels).

Main Results:

• The triple-marker screen identified 75% of trisomy 21 and 67% of trisomy 18 cases.
• All four known trisomy 21 cases in women ≥ 35 years were detected with a 21% false-positive rate.
• Excluding unconjugated estriol would have missed one trisomy 21 case and six other chromosomal abnormalities, without changing the false-positive rate.

Conclusions:

• The addition of unconjugated estriol to triple-marker serum screening significantly increases the detection rate of chromosomal abnormalities.
• The enhanced screening protocol demonstrates improved efficacy compared to protocols without unconjugated estriol.
• Maternal age alone as an indication for amniocentesis warrants reevaluation in light of advancements in serum screening.