Triple-marker prenatal screening program for chromosomal defects.
OBJECTIVE
To examine screening performance of California's triple-marker screening program, using data from a statewide registry for chromosomal defects.


METHODS
This study included 752,686 women who received a screening risk and had an expected date of delivery between July 2005 and the end of June 2007. Follow-up diagnostic services for screen-positive women were performed at state-approved centers. Data on diagnostic outcomes from these visits were entered into the California Chromosomal Defect Registry (CCDR). Other CCDR sources include mandatory reporting by all cytogenetic laboratories and hospitals and outcome data forms submitted by prenatal care providers.


RESULTS
The observed detection rate for Down syndrome (N=1,217) was 77.4%. It varied significantly by gestational dating method and maternal age. The rates for women aged younger than 35 years and 35 years and older were 62.4% and 94.0%, respectively. The detection rates were 81.3% for ultrasound-dated pregnancies and 67.5% for last menstrual period-dated pregnancies. For Turner syndrome, trisomy 18, triploidy, and trisomy 13, the detection rates were 79.4%, 82.5%, 98.1%, and 36.0%, respectively. The positive rate for Down syndrome was 5.4%. Of women with a Down syndrome fetus who were screen positive, only 49.5% opted for amniocentesis. Of women who obtained results from amniocentesis indicating a Down syndrome fetus, 61.4% had an elective termination, 26.2% had a live birth, 4.5% had a death or miscarriage, and 7.9% had an unknown outcome.


CONCLUSIONS
The observed performance of this large triple-marker screening program exceeds generally predicted detection rates for Down syndrome. This study methodology will be used to measure the performance of subsequent screening enhancements.


METHODS
III.
Kazerouni
N Neely
NN
From the Genetic Disease Screening Program, California Department of Public Health, Richmond, California.
Currier
Bob
B
Malm
Linda
L
Riggle
Susan
S
Hodgkinson
Christina
C
Smith
Sylvia
S
Tempelis
Corinna
C
Lorey
Fred
F
Davis
Amber
A
Jelliffe-Pawlowski
Laura
L
Walton-Haynes
Lynn
L
Roberson
Marie
M
D000293:Adolescent; D000328:Adult; D000649:Amniocentesis; D002648:Child; D025063:Chromosome Disorders / Q000175:diagnosis*; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D005865:Gestational Age; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D009261:Nail-Patella Syndrome / Q000175:diagnosis; D011247:Pregnancy; D011256:Pregnancy Outcome; D011296:Prenatal Diagnosis / Q000379:methods*; D014314:Trisomy / Q000175:diagnosis; D016216:Ultrasonography, Prenatal; D055815:Young Adult