ABSTRACT
Multi-marker maternal serum screening for Down syndrome in the second trimester is now part of routine care in many centers. Most protocols use a combination of hCG (or its free beta-subunit) and alpha-fetoprotein (AFP) or unconjugated estriol (UE3), or both. Risk calculation is based on these maternal serum marker values combined with maternal age and trisomy 21 maternal age-related risk. Computer programs are therefore necessary. Both technical and statistical efficiency are included in the final risk evaluation. We studied the Abbott system, comprising AxSym analyzer, AFP and hCG kits and Prenatal Interpretive Software (Maciel). Median values were established between 14 and 18 weeks of amenorrhea in a population of 1822 patients and in twin pregnancies in 157 cases. Forty maternal sera from trisomy 21 affected pregnancies were analyzed. Software was evaluated in a population of 429 patients and in 124 cases of trisomy 21. We conclude that this system constitutes an accurate and efficient method of maternal serum screening for Down syndrome.
