Prenatal Screening for Congenital Defects birth / Монголын Анагаах Ухаан

ABSTRACT

The double and triple test is a prenatal screening used to identify those pregnant women who shouldbe offered a diagnostic test to identify whether their fetus has an aneuploidy. It was first described in1988, but has largely been superseded by newer tests either conducted earlier in the first trimester(ie, the combined test, using ultrasound measurement of nuchal translucency, pregnancy-associatedplasma protein A, and human chorionic gonadotrophin [hCG]) or in the second trimester (ie, thetriple and quadruple test, using α-fetoprotein, hCG, uE3, and inhibin).These newer tests have been introduced because they offer greater detection and lower screenpositive results thereby enhancing diagnosis rates, while decreasing the risk of iatrogenic harmcaused by the invasive testing required when collecting suitable sample tissue. Both first andsecond trimester screening programs have been expanded to include risk assignment for trisomy18. Targeted screening algorithms have not been developed for chromosomal abnormalities otherthan Down syndrome and trisomy 18, although it has been suggested that a trisomy13 risk might becalculated. The construction of such algorithms would require recognition of a characteristic patternfor each condition using the appropriate combination of markers. It is likely, therefore, that the doubleand triple test will continue to be used in routine antenatal care for the foreseeable future.