Double Marker Test (First Trimester Screening) in Ankara
During pregnancy, many screening tests are performed to learn about the health status of the mother and the baby. The Double Marker Test (also known as the Combined Test) is one of the most critical first-trimester tests. This test indicates the risk of chromosomal anomalies in the unborn baby. The Double Marker Test provides accurate results with a rate of 85-90%.
How is the Double Marker Test Performed?
It is performed between the 11th and 14th weeks of pregnancy. It cannot be done before or after these weeks.
1. Ultrasound Examination: First, the baby’s measurements are strictly taken with ultrasonography.
CRL: Crown-Rump Length (Head to butt distance).
NT: Nuchal Translucency (Nape thickness).
Nasal Bone: Presence of the nasal bone.
2. Blood Test: Measurements are recorded on a special form for this test. Information such as the mother’s date of birth, last menstrual period, weight, smoking habits, history of previous pregnancies with chromosomal anomalies, consanguineous marriage, gestational week according to ultrasound, and diabetes status must be written on the form.
Blood is taken from the mother on the same day as the measurement. It is very important that the blood is drawn on the day of the ultrasound measurement. Two values are measured in the blood sample:
Free Beta hCG: Pregnancy hormone.
PAPP-A: Pregnancy-Associated Plasma Protein A.
All information is transferred to a computer environment, and a specific software calculates the Down Syndrome risk.
Why is the Double Marker Test Done?
It is performed to investigate the presence of three specific chromosomal anomalies:
Trisomy 21 (Down Syndrome): The most common anomaly. Known for intellectual disability and organ anomalies.
Trisomy 18 (Edwards Syndrome).
Trisomy 13 (Patau Syndrome).
Ninety percent of babies with Trisomy 13/18 die before birth, and most of those born are lost in the early months. Therefore, Trisomy 21 is the most important focus of the test. This test is done to detect possible anomalies in the fetus in advance and to diagnose pregnancy losses that occur without symptoms.
Interpreting the Results
PAPP-A and hCG are specific to pregnancy. These levels are expected to be at a certain ratio during specific months of pregnancy. However, if there is any anomaly in the baby, differences are seen in these values. In cases of anomaly (Down Syndrome), the PAPP-A value is typically seen as low, and the hCG value as high.
When the protein and hormone values are evaluated in the computer environment:
For Trisomy 21, the risk is considered high if the value is greater than 1/250.
For Trisomy 13/18, the risk cut-off is generally 1/10,000.
Important Note: The Double Marker Test is not for diagnosis, but for screening. This test presents a probability when risk factors (age, smoking, diabetes) and blood results are analyzed. It is never sufficient for a definitive diagnosis alone.
What if the risk is high? If a high risk emerges in the Double Marker Test, further diagnostic tests such as Amniocentesis or screening with higher accuracy like NIPT (Non-Invasive Prenatal Test / Fetal DNA) should be performed.
Is it Mandatory to Have the Test?
The Double Marker Test and other screening tests are procedures that the Ministry of Health requires physicians to inform their pregnant patients about. However, whether to have the test done depends on the patient’s preference.
A pregnant woman who does not want to have the Double Marker Test should state her opinion to her physician and declare in writing that she has been informed about this issue but does not want to have it done.
Who is at Higher Risk?
The risk of giving birth to a baby with anomalies is higher in the following groups:
Pregnant women over the age of 35.
Those with a history of multiple miscarriages.
Those with a previous history of a baby with Down syndrome.
Those with a family history of chromosomal anomalies.
Consanguineous marriages (Marriage between relatives).
Parents with genetic diseases.
Pregnant women with irregular nutrition and harmful habits (Smoking, Alcohol, etc.) during pregnancy.
Double Marker Test Prices in Ankara
Test prices may vary depending on the laboratory where the blood analysis is performed. Since the ultrasound measurement must be done by a specialist Obstetrician, the examination fee is usually separate from the laboratory fee. Please contact our clinic for detailed price information.