Triple-Marker Prenatal Screening Program for Chromosomal Defects

Genetic Disease Screening Program, California Department of Public Health, Richmond, California, USA.
Obstetrics and Gynecology (Impact Factor: 5.18). 08/2009; 114(1):50-8. DOI: 10.1097/AOG.0b013e3181a9479e
Source: PubMed


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

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    • "Followup diagnostic services of genetic counseling, ultrasound and amniocentesis are offered at state-approved Prenatal Diagnosis Centers (PDCs) and the costs of these services are covered by the Expanded AFP Program. Details about the California Prenatal Screening Program and its operation were covered in previous publications (Cunningham et al., 1999; Kazerouni et al., 2009). In July 2007, the California Expanded AFP Screening Program added inhibin as a fourth marker. "
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    ABSTRACT: To evaluate the extent of fetal structural abnormalities, other than neural tube and abdominal wall defects (AWDs), identified by California's Prenatal Screening Program. The Quad Marker Prenatal Screening records of 516,172 women were examined for screening interpretation and the diagnosis of structural abnormalities detected via follow-up. Women who were screen-positive for trisomy 21, trisomy 18, neural tube defects (NTDs) or Smith-Lemli-Opitz syndrome (SLOS) received follow-up services at state-approved Prenatal Diagnosis Centers (PDCs). Detailed reports of services and diagnostic information were linked in a database to the original screening results. A total of 26 323 women received follow-up ultrasound services at the PDCs in the study time period. Of these women, 1085 (4.1%) were identified as having fetuses with significant structural abnormalities, other than NTDs (n = 207) or AWDs (n = 254). In addition to the structural abnormalities, 225 cases of fetal demise, 4 molar pregnancies, 15 cases of twin-to-twin transfusion, and 92 cases with placental abnormalities were identified. While Prenatal Screening Programs do not explicitly screen for structural abnormalities other than NTDs and AWDs, clearly many other structural abnormalities may be associated with a screen-positive status. Thus, the detection of these additional structural defects can be considered an ancillary program benefit.
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