DOUBLE TEST PRENATAL BIOCHEMICAL SCREENING
Extended prenatal biochemical screening – double test and placental growth factor (PlGF) assessment – from maternal serum is the first thing you can do for your child’s health.
WHAT IS PRENATAL BIOCHEMICAL SCREENING?
This is a non-invasive test based on the measurement and interpretation of the levels of three hormonal markers: free β-hCG, PAPP-A, PlGF in combination with the mother’s age and ultrasound markers; the objective of this test is to detect pregnancies at high risk for the most common chromosomal abnormalities (Down syndrome, Edwards syndrome, Patau syndrome).
In addition, by timely identifying pregnancies with a predisposition for developing early preeclampsia (PlGF), this test reduces the risk of premature birth from the first trimester, as well as certain major complications for the mother’s health, allowing for the initiation of prophylactic treatment.
In any pregnancy, there is always a risk that the fetus may have a genetic condition, and in the case of Down syndrome, the incidence at birth in the general population is 1/700 newborns.
1.
Prenatal biochemical screening is a simple blood test intended for every pregnant woman, measuring the levels of specific protein compounds of placental origin in the maternal serum.
2.
Biochemical marker concentrations will be converted into MoMs (Multiple of Median). The MoM equivalent of a specific marker is obtained by dividing the measured value by the median value corresponding to the gestational age—a value specific to the population, method of conception, maternal weight, and smoking status.
3.
By combining these values with ultrasound measurements and maternal age risk, using a certified statistical program, the final risk of having a child with Down, Edwards, or Patau syndrome can be evaluated.
What is the complete prenatal screening associated with preeclampsia risk assessment?
Preeclampsia is a pregnancy-specific condition, a complex multisystemic genetic disease considered the most frequently encountered medical complication in pregnancy. It is characterized by hypertension and proteinuria; in the absence of proteinuria, maternal organ dysfunction can occur without a previously known cause.
What are the biochemical markers?
In the first trimester of pregnancy (weeks 10+0-13+6), three biochemical markers are measured: PAPP-A (Pregnancy Associated Plasma Protein A), Free β-hCG, and PlGF (Placental Growth Factor).
In the second trimester of pregnancy (weeks 14+1-21+6), three biochemical markers are measured: Free β-hCG, AFP (α-fetoprotein), and µΕ3 (Free Estriol).
Where can I perform these tests?
To obtain an increased detection rate of biochemical screening in the first trimester of pregnancy (double test), it is essential that:
1. measurements of biochemical markers be performed in laboratories that have FMF-certified analyzers
2. ultrasound evaluation be performed by doctors specialized in maternal-fetal medicine
3. the risk calculation be obtained using certified software
WHAT IS PREECLAMPSIA?
WHY IS IT IMPORTANT TO PERFORM THIS ANALYSIS AS EARLY AS POSSIBLE IN THE FIRST TRIMESTER OF PREGNANCY?
Preeclampsia affects up to 2-5% of pregnancies and is the leading cause of neonatal and maternal morbidity and mortality. Preeclampsia usually begins relatively late, after 20 weeks of gestational age, in a pregnant woman who previously had normal blood pressure. Without treatment, it can lead to severe complications such as eclampsia and HELLP syndrome, which affect both the mother and the fetus. Therefore, early identification of the risk of preeclampsia as early as the first trimester is extremely important.
In this way, correct pregnancy monitoring and the early initiation of preventive treatment will be possible.
Timely identification of pregnancies with a predisposition for developing preeclampsia allows for their close monitoring (as they are considered high-risk pregnancies) and the initiation of prophylactic treatment with low doses of aspirin. Additionally, by identifying pregnancies at high risk for preeclampsia, it is possible to achieve early detection of intrauterine growth restriction, with which it is often associated. Another positive aspect of early detection is that it gives parents the necessary time to find a hospital with experience in premature care, where the child survival rate is higher.
WHAT ARE THE RISK FACTORS FOR PREECLAMPSIA?
Currently, the following are known as risk factors for preeclampsia:
- first pregnancy at extreme ages (earlier than 20 years or later than 40 years);
- multiple pregnancy;
- inter-pregnancy interval of less than 2 years or greater than 10 years;
- maternal diseases pre-existing the pregnancy such as: chronic arterial hypertension, type 1 or 2 diabetes mellitus, renal disease, systemic lupus erythematosus, antiphospholipid syndrome;
- personal or family history of preeclampsia.
What are the biochemical markers?
- In the second trimester of pregnancy (weeks 14-22), three biochemical markers are measured, requiring the measurement of free-beta HCG (human chorionic gonadotropin), alpha-fetoprotein, and unconjugated estriol from the maternal blood.
- In the second trimester of pregnancy (weeks 14-22), three biochemical markers are measured, requiring the measurement of free-beta HCG (human chorionic gonadotropin), alpha-fetoprotein, and unconjugated estriol from the maternal blood.
Where can I perform these tests?
In order to achieve an increased first-trimester screening (double test) detection rate of 95%, it is essential that:
- measurements of biochemical markers are carried out in Laboratories that have FMF-certified analyzers
- ultrasound evaluation be performed by physicians specialized in maternal-fetal medicine
- risk calculation uses certified software
Cytogenomic Medical Laboratory was the first laboratory in Romania to introduce this advanced screening method as early as 2010.
Since 2010, we have continued to improve through monthly participation in international quality control programs (EQAS-UK) to maintain our position as leaders in this field.
Screening in the first or second trimester of pregnancy: when is the right time?
Although prenatal biochemical screening can be performed in both the first (double test) and second trimester of pregnancy (triple test), in recent years, research results have “shifted” screening toward the first trimester.
First-trimester biochemical results combined with ultrasound parameters: NT (Fetal Nuchal Translucency Thickness), the presence of the nasal bone, CRL (Crown-Rump Length), as well as maternal age, lead to a detection rate of approximately 95%, with 5% false-positive results—data superior to those of the second trimester, which explains the trend in recent years.
Recent studies have shown that the optimal period for collecting and measuring biochemical markers for the double test begins at the 10th week of pregnancy, and for ultrasound measurements, from the 12th to 13th week of pregnancy.
About the accuracy of results and the sensitivity of the method
The value of the optimal risk assessment can only be reached if the information received about the pregnancy is correct, and the measurements of the biochemical markers and Nuchal Translucency have been performed with high precision and accuracy. The BRAHMS KRYPTOR Immunoanalyzer meets these conditions for performing biochemical screening for the first and second trimesters of pregnancy.
Maternal serum prenatal screening is a prognostic test that evaluates the risk for Down syndrome and other chromosomal syndromes for every pregnant woman, therefore there is no “zero risk” result!
A low-risk result does not exclude the existence of maternal-fetal pathology. For cases with high risk, specialty consultation and re-evaluation in maternal-fetal medicine is recommended to continue investigations.