[The triple test].

Abstract

Until the late 80s advanced maternal age was the main indication for prenatal chromosomal diagnosis. The triple test has introduced a noninvasive method for all women to determine the risk of chromosomal abnormality. Not only women aged over 35 years, but also those less than 35 years of age may benefit from the triple test. An exactly performed triple test will allow a diagnosis in 70% of all cases with trisomy 21. Additionally, a positive triple test will be found in 9% of all screened women. 1-2% of the women with a positive triple test will exhibit a fetus with trisomy 21. A false-negative result will be found in 0.1%. Beside trisomy 21, the triple test allows also the diagnosis of pregnancies with a high risk of trisomy 18 and Turner syndrome. The value of the triple test is mainly determined by the quality of the laboratory and the exactness of the determination of the gestational age, which is done mainly by means of ultrasound. Ultrasound investigation also provides information about structural abnormalities. In future the triple test will increase in accuracy and it will be performed in the first trimester.