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 α-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. (Am J Obstet Gynecol 1997;176:1046-51.)