First Trimester Serum Tests for Down's Syndrome Screening

Summary

A Cochrane review [Abstract] 1 included 56 studies with a total of 204 759 pregnancies (2113 with Down's syndrome). 78 test combinations formed from combinations of 18 different tests, with or without maternal age, were evaluated; ADAM12 (a disintegrin and metalloprotease), AFP (alpha-fetoprotein), inhibin, PAPP-A (pregnancy-associated plasma protein A, ITA (invasive trophoblast antigen), free beta-hCG (beta human chorionic gonadotrophin), PlGF (placental growth factor), SP1 (Schwangerschafts protein 1), total hCG, progesterone, uE3 (unconjugated oestriol), GHBP (growth hormone binding protein), PGH (placental growth hormone), hyperglycosylated hCG, ProMBP (proform of eosinophil major basic protein), hPL (human placental lactogen), (free alpha-hCG, and free beta-hCG to AFP ratio. Direct comparisons between two or more tests were made in 27 studies.Meta-analysis of the 9 best performing or frequently evaluated test combinations showed that a test strategy involving maternal age and a double marker combination of PAPP-A and free beta-hCG significantly outperformed the individual markers (with or without maternal age) detecting about 7/10 Down's syndrome pregnancies at a 5% false positive rate. Limited evidence suggested that marker combinations involving PAPP-A may be more sensitive than those without PAPP-A.