Pregnancy is a special period in which regular check-ups are of great importance for the health of both the mother and the baby. Among these check-ups, the double screening test performed between the 11th and 14th weeks of pregnancy stands out as an effective method that evaluates the risk of certain chromosomal abnormalities in the baby. In this article, we will examine in detail what the double screening test is, how it is performed, who needs it, and how its results are interpreted.
1. What is the Double Screening Test?
The double screening test is a non-invasive test that enables the early detection of chromosomal abnormalities, especially Down syndrome (Trisomy 21) and Edwards syndrome (Trisomy 18). The test is based on two main parameters:
- Biochemical tests in maternal blood: The levels of certain hormones and proteins are measured from a blood sample taken from the mother.
- Ultrasound measurements: The baby’s nuchal translucency (NT) and some anatomical features are examined by ultrasound.
By combining these two data, the baby’s risk of chromosomal abnormality is calculated. The test helps to identify high-risk pregnancies and, if necessary, guides further diagnostic procedures.
2. When is the Double Screening Test Performed?
The double screening test is usually performed between the 11th and 14th weeks of pregnancy. This period is when ultrasound measurements can be made accurately and biochemical values are reliable. Conducting the test within this time frame allows early identification of risky pregnancies and referral to diagnostic tests if needed.
3. How is the Double Screening Test Performed?
The double screening test is a non-invasive method in terms of mother and baby safety and is generally carried out through the following steps:
- Patient Preparation: Usually, no special preparation is required before the test. Fasting is not necessary.
- Maternal Blood Sample: A blood sample is taken from the mother’s vein and sent to the laboratory for biochemical analysis.
- Ultrasound Measurements: A specialized ultrasound technician or perinatologist measures the baby’s nuchal translucency and performs some basic anatomical assessments. This measurement is a critical parameter in risk calculation.
- Data Analysis: Maternal age, gestational week, biochemical values, and ultrasound measurements are combined in computerized systems. This allows the calculation of the risk for Down syndrome and Edwards syndrome.
4. The Importance of the Double Screening Test
The double screening test provides early risk assessment during pregnancy. Its importance can be summarized as follows:
- Early Diagnosis: Enables early detection of chromosomal abnormalities such as Down syndrome and Edwards syndrome.
- Safe and Non-Invasive: There is no risk to the mother or baby during the test.
- Guidance: If the test result indicates high risk, the mother can be referred to advanced diagnostic tests (such as amniocentesis or chorionic villus sampling).
- Psychological Support for the Mother: Knowing whether the risk is low or high helps the expectant mother prepare more consciously for childbirth.
5. Advantages of the Double Screening Test
- Quick and Easy Application: The test takes a short time and is generally comfortable for the patient.
- Early Risk Identification: Early determination of risk during pregnancy facilitates diagnosis and planning.
- Minimal Side Effects: As a non-invasive test, it does not harm the mother or baby.
- Accurate Guidance: In high-risk cases, it allows transition to more advanced and definitive diagnostic methods.
6. How are Double Screening Test Results Interpreted?
The results are usually reported as “low risk” or “high risk”:
- Low Risk: Indicates that the baby’s risk of chromosomal abnormality is low. In this case, further testing is usually unnecessary.
- High Risk: If the result is high risk, advanced diagnostic methods are recommended. These include amniocentesis or chorionic villus sampling, which provide definitive diagnosis of chromosomal abnormalities.
7. Who Should Have the Double Screening Test?
The double screening test is recommended for all pregnancies but is especially important in the following situations:
- Mothers over 35 years of age
- Pregnancies with a previous history of chromosomal abnormality
- Families with a history of Down syndrome or other chromosomal disorders
- Pregnancies in which abnormalities were detected in ultrasound or blood tests
8. Alternatives to the Double Screening Test
Some alternative or complementary tests include:
- Triple Screening Test (Triple Test): Performed between the 15th and 20th weeks of pregnancy, analyzing different biochemical parameters.
- Quadruple Screening Test (Quad Test): A more comprehensive version of the triple test with an additional parameter for risk evaluation.
- Non-Invasive Prenatal Test (NIPT): Analyzes fetal DNA in maternal blood, providing a more sensitive assessment of chromosomal risk.
The double screening test is a safe and effective method for evaluating the risk of chromosomal abnormalities in early pregnancy. Its non-invasive nature and lack of risk for both mother and baby are its greatest advantages. Early risk assessment, possible referral to advanced diagnostics, and preparation for childbirth make it highly valuable. While it can be applied to all pregnancies, it is particularly critical for older mothers and those with additional risk factors.