Maternal serum screening for Down syndrome in the United States: a 1995 survey.

OBJECTIVE

Our goal was to determine the status of prenatal Down syndrome screening in the United States in 1995.

STUDY DESIGN

Information was sought via questionnaire from laboratories participating in external proficiency testing.

RESULTS

Services were provided to 2,498,000 women annually by 265 screening laboratories. All but 10 laboratories offered both open neural tube defect and Down syndrome screening. Twenty-one percent of Down syndrome interpretations were based on alpha-fetoprotein measurements alone; 79% also included other serum analytes. Sixty-six laboratories (26%) offered interpretations at 14 weeks' gestation or earlier.

CONCLUSIONS

Some laboratories extend serum screening too early in gestation for optimal neural tube defect interpretation. When 1995 was compared with 1992, more women were being screened, a higher proportion were receiving a Down syndrome interpretation, and more interpretations were based on multiple analytes. Laboratories should be encouraged to use some combination of multiple markers when screening for Down syndrome.