Screening for chromosomal abnormalities using combined test in the first trimester of pregnancy

OBJECTIVE: This study was designed to review the screening performance of combined test at the Ewha Womans University Mokdong hospital. METHODS: All women admitted for routine antenatal care between January 1st 2008 and December 31st 2012 with a known pregnancy outcome were included in this study, totaling 1,156 women with singleton pregnancies presenting at 10 to 13 weeks of gestation. Women were offered screening using a combination of maternal serum pregnancy-associated plasma protein-A, free β-human chorionic gonadotropin and fetal nuchal translucency thickness. Those with an estimated risk of ≥1 in 250 of carrying a fetus with trisomy 21 or ≥1 in 300 risk of trisomy 18 were offered genetic counseling with the option of an invasive diagnostic test. RESULTS: The median of gestational age was 11+3 weeks, the median of crown-rump length was 47.1 mm, and the median age of the women was 31 years. The detection rate was 80% for trisomy 21 (4 of 5) and 100% for trisomy 13 and 18 (all 2). The false-positive rate was 7.73% for trisomy 21 and 1.21% for trisomy 18. CONCLUSION: This study was the first large population study performed with the aim of analyzing the performance of the combined test in Korea. This study demonstrated that the detection rates and other figures of the first trimester combined test are comparable to the results reported in other papers worldwide. Consequently, if strict conditions for good screening outcomes are achieved, the first trimester combined test might well be the earliest detectable screening, improving detection rates without increasing karyotyping or economic and other implications that inevitably ensue.

Screening for chromosomal abnormalities using combined test in the first trimester of pregnancy

OBJECTIVE: This study was designed to review the screening performance of combined test at the Ewha Womans University Mokdong hospital. METHODS: All women admitted for routine antenatal care between January 1st 2008 and December 31st 2012 with a known pregnancy outcome were included in this study, totaling 1,156 women with singleton pregnancies presenting at 10 to 13 weeks of gestation. Women were offered screening using a combination of maternal serum pregnancy-associated plasma protein-A, free β-human chorionic gonadotropin and fetal nuchal translucency thickness. Those with an estimated risk of ≥1 in 250 of carrying a fetus with trisomy 21 or ≥1 in 300 risk of trisomy 18 were offered genetic counseling with the option of an invasive diagnostic test. RESULTS: The median of gestational age was 11+3 weeks, the median of crown-rump length was 47.1 mm, and the median age of the women was 31 years. The detection rate was 80% for trisomy 21 (4 of 5) and 100% for trisomy 13 and 18 (all 2). The false-positive rate was 7.73% for trisomy 21 and 1.21% for trisomy 18. CONCLUSION: This study was the first large population study performed with the aim of analyzing the performance of the combined test in Korea. This study demonstrated that the detection rates and other figures of the first trimester combined test are comparable to the results reported in other papers worldwide. Consequently, if strict conditions for good screening outcomes are achieved, the first trimester combined test might well be the earliest detectable screening, improving detection rates without increasing karyotyping or economic and other implications that inevitably ensue.

Clinical implications of nuchal translucency / 대한산부인과학회지

Fetal nuchal translucency (NT) is an echolucent space between the dorsal edge of soft tissue of the fetal neck and the linear echo of the skin observed in a midsagittal image measured at 11 to 13(+6) weeks of gestation. Increased NT (>95 percentile) is highly associated with fetal aneuploidy and congenital structural anomalies including congenital heart defects. In combination with maternal serum PAPP-A and free beta-hCG, increased NT has been demonstrated to provide efficient Down syndrome risk assessment, with a detection rate of 80-87% (5% false-positive rate), and it also allows earlier diagnosis of fetal aneuploidy. Even in the absence of aneuploidy, increased NT is still associated with an increase in adverse perinatal outcome including abortion, fetal death and a variety of fetal malformations. This paper will review the mechanism of increased NT, correct measurement of NT, and recent evidences for interpretation and management for the fetuses with increased NT.

Interpretation of antenatal screening methods / 대한산부인과학회지

For definitive antenatal diagnosis of fetal aneuploidy, invasive tests such as chorionic villous sampling, amniocentesis and cordocentesis are required for chromosome analysis. However, to reduce the risk of miscarriage associated with procedural complications, it is important to detect pregnant women with high risk of fetal aneuploidy. Recently, there have been advances in maternal serum and sonographic markers for screening of chromosomal defects in the first and second trimester. The serum screening methods include first trimester screening with nuchal translucency and second trimester multi marker screening. Particularly, combining first and second trimester results can increase the detection rate of Down syndrome with lower false-positive rates. In addition to biochemical markers, second trimester sonogram to detect major and minor sonographic markers for chromosomal defects is important to identify the high risk pregnancy. To detect the fetal aneuploidy with high specificity and sensitivity, we need to interpret the maternal age, the results of first and second trimester serum markers and genetic sonographic findings all together.