Down syndrome maternal serum marker screening after 18 weeks of gestation: a countrywide study.
OBJECTIVE
The objective of the study was to evaluate the efficacy of maternal serum markers in detecting Down syndrome after 18 weeks of gestation in women who book late for maternity care in a large national retrospective study.


METHODS
During the period 2007-2012, 27,648 women, regardless of maternal age (17.4% were 35 years old and over), were included in a late Down syndrome screening program (18(+0) to 35(+6) weeks) using the maternal serum markers alpha-fetoprotein and human chorionic gonadotrophin-beta. Samples were assayed in a single laboratory. A dataset of median markers previously established in our laboratory was used for risk calculation. The control group consisted of 27,648 women (14(+0) to 17(+6) weeks) randomly selected from the routine database.


RESULTS
When the later screening group was compared with the standard second-trimester control group, the median multiples of medians (1.01 vs 0.98 for alpha-fetoprotein, 1.03 vs 0.98 for human chorionic gonadotrophin-beta), median risks (1 of 2414 vs 1 of 2720), false-positive rates (11.1% vs 11.6%), and trisomy 21 detection rates (83.3% vs 85.7%) did not differ significantly.


CONCLUSIONS
Late Down syndrome maternal serum screening is feasible with a good sensitivity/specificity compromise throughout gestation and is of clinical value in late-booking women.
Department of Biochemistry Hôpital Robert Debré, Assistance Publique-Hôpitaux de Paris, Paris, France.
Sophie
S
Dreux
Claire
C
Nguyen
Isabelle
I
Czerkiewicz
Thomas
T
Schmitz
Elie
E
Azria
Marc-Antoine
MA
Fouré
Françoise
F
Muller
D000328:Adult; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D004314:Down Syndrome / Q000175:diagnosis*; D005189:False Positive Reactions; D005260:Female; D005602:France; D006801:Humans; D008403:Mass Screening / Q000379:methods*; D062145:Maternal Serum Screening Tests; D008875:Middle Aged; D011247:Pregnancy; D011262:Pregnancy Trimester, Second / Q000097:blood*; D011295:Prenatal Care / Q000379:methods*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D000509:alpha-Fetoproteins / Q000378:metabolism*
C097353:AFP protein, human; D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human; D000509:alpha-Fetoproteins