[Screening for Down syndrome using first-trimester combined screening followed by second trimester ultrasound examination in an unselected population].
BACKGROUND
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 week anomaly scan.


METHODS
We carried out a multi-centre, 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 non verified 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 euro (120 $) per woman and the cost per diagnosed Down syndrome pregnancy was 7,118 euro (7,909 $).


CONCLUSIONS
Our findings suggest that one pragmatic interventional two-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
P
P
Département de gynécologie-obstétrique, biologie de la reproduction et cytogénétique, CHI Poissy-Saint-Germain, hôpital Poissy-Saint-Germain, université Versailles-Saint-Quentin, Poissy, France. prozenberg@chi-poissy-st-germain.fr
Bussières
L
L
Chevret
S
S
Bernard
J-P
JP
Malagrida
L
L
Cuckle
H
H
Chabry
C
C
Durand-Zaleski
I
I
Bidat
L
L
Lacroix
I
I
Moulis
M
M
Roger
M
M
Jacquemot
M-C
MC
Bault
J-P
JP
Boukobza
P
P
Boccara
P
P
Vialat
F
F
Giudicelli
Y
Y
Ville
Y
Y
D000328:Adult; D015415:Biomarkers / Q000097:blood; D003365:Costs and Cost Analysis; D003937:Diagnosis, Differential; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008423:Maternal Age; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011296:Prenatal Diagnosis / Q000191:economics / Q000379:methods; D012307:Risk Factors; D016216:Ultrasonography, Prenatal
D015415:Biomarkers