Maternal serum screening for fetal Down syndrome in the United States: A 1992 survey

OBJECTIVE: Our purpose was to determine the status of screening for fetal Down syndrome in the United States in 1992. STUDY DESIGN: Information was sought from laboratories participating in two proficiency testing programs. RESULTS: The 301 responding laboratories (98%) annually provided services to 2,113,000 pregnant women. Of these laboratories, 242 provided Down syndrome screening (1,924,000 pregnant women); 55% used a-fetoprotein levels alone, 30% used α-fetoprotein, unconjugated estriol, and human chorionic gonadotropin combined, and 14% used a-fetoprotein and human chorionic gonadotropin combined. All laboratories used clinically validated analytes. Nearly all screened at appropriate gestational ages, used a validated algorithm, and used risk as the screening variable. However, many laboratories, especially smaller ones, were unable to monitor their performances adequately. CONCLUSION: Since 1988 maternal serum screening for Down syndrome has approximately doubled, and other analyte measurements have been added in nearly one fourth of the screened pregnancies. Most laboratories appear to be performing adequately, although there is room for improvement.