Korean J Clin Pathol.  2000 Feb;20(1):18-23.

Evaluation of the Dual Test using PAPP-A and Free beta-hCG in First Trimester as a Prenatal Screening Test for Down Syndrome

  • 1Department of Clinical Pathology, College of Medicine, Pochon CHA University, Seoul, Korea. young@cha.ac.kr
  • 2Department of Clinical Pathology, College of Medicine, Ewha Womans University, Seoul, Korea.


BACKGROUND: Dual test has been reported to be a useful first trimester screening test for Down syndrome and is comprised of measuring two serum parameters; pregnancy associated plasma protein A(PAPP-A) and free beta chorionic gonadotrophin(beta-hCG). This study was performed to investigate the distribution of these two parameters in Korean pregnant women and compare its significance with that of Triple test which is a second trimester screening test and being more commonly used in Korea.
For the Dual test, serum PAPP-A and free beta-hCG were each measured by radioimmunoassay(AMERLEX-M kitTM) in 2,526 first-trimester pregnant women. Triple test was done in 7,007 second-trimester pregnant women.
The median value of PAPP-A was 9.3, 12.5, 18.1 and 26.6 IU/mL, and that of free beta-hCG was 47.8, 35.4, 29.4 and 29.3 nmol/L in 10th, 11th, 12th and 13th gestational week, respectively. The Dual test was positive in 7.8%(198/2,526), while the Triple test was positive in 3.0%(208/7,007). Among 87 Dual test positive cases, Down syndrome was diagnosed in three cases(3.5%), while 71 Triple test positive cases, seven cases(9.9%) were Down syndrome. Among 1,316 cases who had both the Dual and Triple test, 1,300(98.8%) were both negative, and two(0.2%) were both positive, showing 99% of concordance rate.
These results showed a possibility that the Dual test could be used as a valuable first-trimester screening test for Down syndrome in our country.


First trimester; Down syndrome; PAPP-A; Free beta-hCG

MeSH Terms

Down Syndrome*
Mass Screening
Pregnancy Trimester, First*
Pregnancy Trimester, Second
Pregnancy-Associated Plasma Protein-A*
Pregnant Women
Prenatal Diagnosis*
Pregnancy-Associated Plasma Protein-A
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