title: Down syndrome maternal serum marker screening after 18 weeks' gestation.
abstract: Women having access to prenatal care late in pregnancy may still wish to benefit from maternal serum screening for Down syndrome. Therefore, we established reference values for alpha-feto protein (AFP) and free beta-human chorionic gonadotrophin (beta-hCG), and assessed the diagnostic value of maternal serum marker screening at 18-35 weeks' gestation based upon a series of 4072 sera from unaffected pregnancies and 118 sera from pregnant women with fetuses affected by Down syndrome. Using a 1/250 risk cut-off, a detection rate of 72.9% (95% CI = 71.5-74.3%) was achieved with a false-positive rate of 7.51% (95% CI = 6.71-8.3%). This was not significantly different from the percentages observed in our 14-17 weeks routine screening (50 596 patients): 71.9% (95% CI = 71.5-72.3%) and 6.48% (95% CI = 6.28-6.68%), respectively. Detection and screen-positive rates were, respectively, 51.3% (95% CI = 35.6-67.0%) and 5.95% (95% CI = 5.12-6.68%) in women aunder 35 years of age, and 84.8% (95% CI = 76.9-92.7%) and 24% (95% CI = 20.7-27.3%) in women aged 35 years and over. In conclusion, maternal serum marker screening is feasible at 18 weeks' gestation and later, which may be of interest in selected cases.
authors.affiliation: Service de Biochimie, Hôpital Ambroise Paré, Boulogne, France. francoise.muller@apr.ap-hop-paris.fr
authors.forename: Françoise
authors.initials: F
authors.lastname: Muller
authors.forename: Sophie
authors.initials: S
authors.lastname: Dreux
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Oury
authors.forename: Dominique
authors.initials: D
authors.lastname: Luton
authors.forename: Serge
authors.initials: S
authors.lastname: Uzan
authors.forename: Michèle
authors.initials: M
authors.lastname: Uzan
authors.forename: Michel
authors.initials: M
authors.lastname: Levardon
authors.forename: Marc
authors.initials: M
authors.lastname: Dommergues
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood*; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000032:analysis*; D004314:Down Syndrome / Q000175:diagnosis*; D005189:False Positive Reactions; D005260:Female; D005865:Gestational Age; D006801:Humans; D008403:Mass Screening; D008423:Maternal Age; D011237:Predictive Value of Tests; D011247:Pregnancy / Q000097:blood*; D018566:Pregnancy, High-Risk; D011296:Prenatal Diagnosis; D012016:Reference Values; D000509:alpha-Fetoproteins / Q000032:analysis*
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human; D000509:alpha-Fetoproteins