PRENATAL BIOCHEMICAL SCREENING

Extended prenatal biochemical screening –double test and placental growth factor (PlGF) – from the maternal serum is the first step you can take to check if your child is healthy.

Double test and placental growth factor (PlGF)

What is prenatal biochemical screening?

The combined non-invasive screening test is based on measuring and interpreting the level of three placental hormones: free β-hCG, PAPP-A, PlGF associated with the mother’s age, and the fetalultrasound markers and is intended to detect high risk pregnancies for the most common chromosomal abnormalities (Down syndrome, Edwards syndrome, Patau syndrome).
Moreover, with the timely detection of pregnancies with high-risk for early preeclampsia, the test allowes for the timely treatment of patients and the lowering of preeclampsia rates.
Everyone has a risk of having a fetus affected by Down syndrome and the risk increases drasticly for the maternal age over 35. The prevalence of Down syndrome in the general population is 1/700 newborns.

1.

Prenatal biochemical screening is a simple blood test intended for every pregnant woman, to measure the level of certain protein compounds of placental origin in the maternal serum.

2.

The concentrations of the biochemical markers are converted toMoMs (Multiple of Median). The equivalent MoM of a certain marker is computed by dividing the value measured at the value of the median corresponding to the pregnancy age, a value which is specific for the population, conception method, mother’s weight, and smoking status.

3.

By combining these values with the ultrasound measurements and with the maternal age risk using a certified statistics program we can assess the final risk of having a child with Down, Edwards, or Patau syndrome.

How can the preeclampsia risk be evaluated?

Preeclampsia is a pregnancy-specific condition, a complex genetic multisystem disorder considered to be the most frequent medical complication during pregnancy. It is characterised by hypertension, proteinuria, and in the lack of proteinuria, there might be dysfunctions of the mother’s organs without any previously known cause.
Which are the biochemical markers?
Three biochemical markers are measured during the first trimester of pregnancy (weeks 10+0-13+6): PAPP-A (Pregnancy Associated Plasma Protein A), Free β-hCG (Free β-human Chorionic Gonadotropin), and PlGF (Placental Growth Factor).
Three biochemical markers are being measured during the second trimester of pregnancy (weeks 14+1-21+6): Free β-hCG (Free β-human Corionic Gonadotropin), AFP (α-fetoprotein), and µΕ3 (Free Estriol).

Where can I have these tests done?

The following requirements need to be met to get a high detection rate of the biochemical screening during the first trimester of pregnancy (double test):
1. The biochemical markers must be measured in a laboratory using FMF-certified analysersF
2. The ultrasound examination must be performed by doctors specialized in maternal and foetal medicine
3. The risk must be computed using a certified software

CytoGenomic Laboratory was the first laboratory in Romania to have introduced this advanced screening method in 2010.

Since 2010, we keep up to date by attending international quality control programmes (EQAS-UK) on a monthly basis to preserve our status as leaders in this field.
Screening during the first or the second trimester of pregnancy? When is the best time to have it done?

Although prenatal biochemical screening can be performed both during the first (as double test), and the second trimester of pregnancy (triple test), over the last years the outcomes of the studies done “shifted” screening towards the first trimester of pregnancy.

The biochemical results of the first trimester of pregnancy associated with the ultrasound parameters: NT (Fetal Nuchal Translucency Thickness), the measurement of the nasal bone, CRL (Crown-Rump Length), and with the maternal age lead to a detection rate of around 95%, with 5% falsely positive results, which are better than those from the second trimester screening.

Recent studies showed that the optimal period for collecting and measuring biochemical markers for the double test starts in the 10th week of pregnancy, while the optimal period for ultrasound measurements is between the 12thand the 13th week of pregnancy.

On result accuracy and method sensitivity

An optimal risk assessment can be obtained if the information about the pregnancy is accurate and the biochemical markersand Nuchal Translucenc ymeasurements have been performed using a highly accurate technique. The BRAHMS KRYPTOR Immunoanalyzer meets these requirements.

Screeningul prenatal din serul matern este un test prognostic care evaluează riscul pentru sindrom Down și alte sindroame cromozomiale în cazul fiecărei femei gravide, așadar nu există rezultat “fără risc”!

A low risk result does not exclude a maternal and foetal pathology.
In high-risk cases, additional tests can be required to further asses the foetus.

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