Screening for Down syndrome using first-trimester combined screening followed by second-trimester ultrasound examination in an unselected population.
OBJECTIVE
Recent studies have reported the efficacy of first-trimester combined screening for Down syndrome based on maternal age, serum markers (human chorionic gonadotropin, pregnancy-associated plasma protein A), and ultrasound measurement of fetal nuchal translucency. However, those do not incorporate the value of the widely accepted routine 20-22 weeks' anomaly scan.


METHODS
We carried out a multicenter, interventional study in the unselected population of a single health authority in order to assess the performance of first-trimester combined screening, followed by routine second trimester ultrasound examination and/or screening by maternal serum markers (free beta-hCG and alpha-fetoprotein measurement or total hCG, alpha-fetoprotein, and unconjugated estriol measurement) when incidentally performed. Detection and screen positive rates were estimated using a correction method for nonverified issues. A cost analysis was also performed.


RESULTS
During the study period, 14,934 women were included. Fifty-one cases of Down syndrome were observed, giving a prevalence of 3.4 per 1000 pregnancies. Of these, 46 were diagnosed through first (n = 41) or second (n = 5) trimester screening. Among the 5 screen-negative Down syndrome cases, all were diagnosed postnatally after an uneventful pregnancy. Detection and screen positive rates of first-trimester combined screening were 79.6% and 2.7%, respectively. These features reached 89.7%, and 4.2%, respectively, when combined with second-trimester ultrasound screening. The average cost of the full screening procedure was 108 euros (120 dollars) per woman and the cost per diagnosed Down syndrome pregnancy was 7,118 euros (7909 dollars).


CONCLUSIONS
Our findings suggest that 1 pragmatic interventional 2-step approach using first-trimester combined screening followed by second-trimester detailed ultrasound examination is a suitable and acceptable option for Down syndrome screening in pregnancy.
Rozenberg
Patrick
P
Department of Obstetrics and Gynecology, Reproductive Biology and Cytogenetics, Poissy-Saint Germain Hospital, University Versailles-St Quentin, Poissy, France. prozenberg@chi-poissy-st-germain.fr
Bussières
Laurence
L
Chevret
Sylvie
S
Bernard
Jean Pierre
JP
Malagrida
Lydia
L
Cuckle
Howard
H
Chabry
Chantal
C
Durand-Zaleski
Isabelle
I
Bidat
Laurent
L
Lacroix
Isabelle
I
Moulis
Max
M
Roger
Marc
M
Jacquemot
Marie Christine
MC
Bault
Jean Philippe
JP
Boukobza
Philippe
P
Boccara
Patrick
P
Vialard
Francois
F
Giudicelli
Yves
Y
Ville
Yves
Y
D000328:Adult; D004314:Down Syndrome / Q000175:diagnosis* / Q000453:epidemiology; D005260:Female; D017048:Health Care Costs; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011296:Prenatal Diagnosis / Q000191:economics / Q000592:standards; D015995:Prevalence; D016216:Ultrasonography, Prenatal / Q000191:economics / Q000592:standards