In which week of pregnancy is the double test performed?

This is an automatically translated article.

The article was professionally consulted with Doctor Nguyen Anh Tu - Doctor of Obstetric Ultrasound - Prenatal Diagnosis - Department of Obstetrics - Vinmec Hai Phong International General Hospital.

The Double Test is a screening test that uses Biochemistry and nuchal translucency tests using ultrasound to assess some of the risk of Down, Edward, or Patau syndromes in the first trimester of pregnancy.

1. Double test

Double test is done in pregnant women, to screen for the risk of genetic defects in the fetus such as Down syndrome, Edwards syndrome (Trisomy 18) and Patau (Trisomy 13).
Double test screening results will be calculated based on the following factors:
Check and quantify free β-hCG (free beta-human chorionic gonadotropin) and PAPP-A (pregnancy associated plasma protein A) in the blood of pregnant women. These are two substances secreted by the fetus into the mother's blood. Combined with ultrasound results of nuchal translucency (NT), head - rump length (CRL) of the fetus. Maternal age, gestational age and some other health information.

2. At what week is the Double test performed?

With the Double test, pregnant women should do it when the fetus is 11-13 weeks old, preferably at 12 weeks pregnant, ie right in the first trimester of pregnancy.
This is because free β-hCG and PAPP-A levels change throughout pregnancy.
Free β-hCG is a structural component of hCG hormone. hCG is first secreted by the trophoblasts of the fertilized egg, and then by the placenta. hCG is present in the mother's serum between 6 and 8 days after the egg is fertilized and peaks between 50 and 80 days after the last menstrual period. If the fetus has Down syndrome, the concentration of free β-hCG will increase significantly during the first and second trimesters of pregnancy.

Xét nghiệm double test được thực hiện vào tuần thai nào? — Với xét nghiệm Double test, thai phụ nên thực hiện khi thai nhi 11 - 13 tuần tuổi

PAPP-A is a glycoprotein secreted by the placenta. Normally, PAPP-A levels will gradually increase throughout pregnancy. During the first trimester of pregnancy, if the fetus has Down syndrome, the concentration of PAPP-A in the mother's blood decreases. Meanwhile, in the second quarter, PAPP-A levels remained at normal levels or slightly decreased insignificantly. Therefore, PAPP-A is only used during the first trimester of pregnancy to screen fetuses with Down syndrome.

3. How long does it take to get the results of the Double test?

The doctor collects a blood sample from the mother's hand vein for testing. The analysis results of Double test can be available from a few hours to 2.3 days, depending on the facility.
Double Test is one of the prenatal screenings included in the 12-week Maternity package at Vinmec, helping to detect abnormal problems during pregnancy and protect the health of mother and baby. Depending on the stage of pregnancy, pregnant women will be consulted by the doctor for appropriate tests to check the development status of the baby.
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