What is a Double Screening Test Turkey?
The double screening test Turkey is a non-invasive screening method that aims to determine the risk of certain chromosomal anomalies and neurological tube defects in the fetus during early pregnancy. The levels of two biochemical markers, free β-hCG (human chorionic gonadotropin) and PAPP-A (pregnancy-associated plasma protein A), are measured in a blood sample taken from the mother between the 10th and 14th weeks of pregnancy. After the measured hormone values are corrected for factors such as maternal age, weight, gestational week and smoking, a statistical model is used to calculate the risk. If a high risk is found as a result of the screening, the need for advanced invasive diagnostic methods or detailed ultrasonographic examination is revealed.
When is the Double Marker Screening Test Performed?
The double screening test is performed between the 10th and 14th weeks of pregnancy, immediately following the organogenesis period of the embryo. During this period, the reference ranges for both β-hCG and PAPP-A hormones are at a level that will provide the most reliable diagnostic results. When the test is performed before the 10th week, the risk of false negatives increases because the PAPP-A level may be very low, and after the 14th week, the false positive rate may increase due to the decrease in hormones. Therefore, adhering to this ideal time period is critical both in terms of avoiding invasive procedures for the fetus and increasing the reliability of screening.
What Values Are Measured in the Test? (Beta-HCG and PAPP-A)
Free β-hCG is a hormone secreted by the placenta and plays a role in maintaining pregnancy, and shows higher than normal values in pregnancies with Down syndrome. PAPP-A is a protein found in maternal plasma; its levels decrease significantly in aneuploidies such as Down and Edwards syndrome. Both parameters are determined quantitatively in the blood sample using chemiluminescence-based immunological methods. The measured values are standardized in the form of MoM (multiple of median) according to the expectant mother’s gestational week and then entered into the risk algorithm in combination.
What Risks Does the Double Marker Screening Test Identify?
The double screening test provides a sensitive screening, especially for the risk of Trisomy 21 (Down syndrome) and Trisomy 18 (Edwards syndrome). In addition, in some models, it may be an additional predictor for the risk of Trisomy 13 and molar pregnancy. The test does not directly measure a parameter for neural tube defect screening; however, the risk of neural tube defect is indirectly assessed by simultaneous NT measurement during this period and, if necessary, by the AFP value to be taken in the second trimester. In cases found to be at high risk, invasive chorionic villus sampling or amniocentesis is recommended for definitive diagnosis.
How is a Double Screening Test Performed?
After the 10th week of pregnancy is completed, approximately 5–10 ml of blood is taken from the mother’s arm vein. After the serum is separated, β-hCG and PAPP-A levels are measured quantitatively by immunoassay in hospital laboratories. Sample results are entered into the hospital information system along with variables such as the patient’s gestational age, age, weight, race and smoking history. Based on these inputs, the risk calculation software reports the risk value of both chromosomal anomalies calculated as 1/X.
Dual Scanning Combined with Ultrasound (NT Measurement)
In order to provide the highest accuracy in medical practice of the double screening test, the nuchal translucency (NT) measurement performed between the 11th and 14th weeks is combined with blood values. The NT thickness obtained by transvaginal or abdominal ultrasound is the measurement of the fluid space in the subnasal region of the fetus in millimeters. Increased NT is an important predictor of the risk of chromosomal anomalies and congenital heart disease. The simultaneous evaluation of NT measurement with free β-hCG and PAPP-A results increases the screening sensitivity up to 90% compared to biochemical or ultrasound screening alone.
How to Interpret Test Results?
Test results are presented as risk values expressed separately for Trisomy 21 and Trisomy 18 in the form of 1/X. For example, a risk of 1/200 indicates that the relevant anomaly is statistically likely to occur in 1 in 200 pregnancies. The clinically determined cut-off value is usually 1/300; cases reported above this threshold are considered “high risk” and invasive diagnosis is recommended. Results below the cut-off value are considered “low risk”, but since no screening test provides 100% certainty, follow-up continues in low-risk cases according to ultrasound data and patient preferences. In cases of high risk, chorionic villus sampling or amniocentesis is planned together with genetic counseling. Each case is handled by a multidisciplinary team with patient education and psychosocial support.
Is the Double Marker Test Reliable?
The double screening test, by combining free β-hCG and PAPP-A levels as well as NT measurement, reaches a sensitivity of approximately 85–90% for the detection of Trisomy 21 and 80–85% for Trisomy 18. While the false positive rate remains around 3–5%, the negative predictive value of the test is quite high. However, since no screening test provides a 100% diagnosis, ultrasonography data and patient history are also taken into account in risk assessment. In this respect, double screening is a reliable pre-screening method and guides the clinic in distinguishing high- or low-risk pregnancies.
What to Do If Test Results Are Risky?
If the double screening results report a risk above the cut-off value (usually 1/300), genetic counseling is recommended for the patient. Then, referral is made to invasive diagnostic methods such as CVS (chorionic villus sampling) at 11–14 weeks of pregnancy or amniocentesis at 15–20 weeks. These interventions allow fetal chromosome analysis and confirm the risk predicted by the screening test. At the same time, detailed anatomy ultrasonography is repeated to detect detailed fetal anomalies and, if necessary, complementary tests such as fetal echocardiography and neural tube examination are planned.
Dual Screening Test Prices 2025
As of 2025, double screening test fees in private laboratories and clinics will range from ₺1,500 to ₺2,500. This package includes blood collection, β-hCG and PAPP-A analyses, NT measurement ultrasound, risk calculation report and genetic counseling guidance. In addition, some centers offer “genetic screening packages” that include detailed ultrasound and Doppler examinations in the range of ₺3,000 – ₺4,000. For patients covered by the Social Security Institution, package examinations and basic screening tests are largely free of charge; only additional ultrasounds or counseling fees may be charged.
Frequently Asked Questions
Is the double marker screening test done on an empty stomach?
There is no special fasting requirement before the blood sample is taken for double screening; it is sufficient for the expectant mother to continue her normal diet. Since there is no significant post-meal change affecting the measurement of PAPP-A and β-hCG hormones, the tests are generally performed safely on a full stomach. However, some centers may recommend skipping a light meal 2 hours before blood collection, in accordance with the recommendation of hemologists; this aims to increase the quality of the sample and minimize laboratory errors. In general practice, there is no fasting requirement; drinking plenty of water is sufficient.
When Will Results Be Available?
The results of the double screening test are usually available from the laboratory on the same day the blood sample is taken or the following business day. After the serum analysis is completed, the data combined with the NT measurement is entered into the risk calculation software and a detailed report is generated within 24–48 hours. We will inform you when your test result is ready, and if you wish, we will provide you with preliminary information by phone or e-mail and then make an appointment for face-to-face counseling.
If the Results Are Risky, Does It Mean the Baby Is Sick?
A high-risk result does not necessarily mean that the baby has a definite disease; it only indicates that the probability of a chromosomal abnormality has increased. At this stage, a definitive diagnosis is made by performing fetal chromosome analysis with invasive diagnostic methods—chorionic villus sampling or amniocentesis. We provide genetic counseling to expectant mothers who receive a high-risk report, and manage the process in a transparent and supportive manner.
Can a Spouse Participate in the Dual Screening Test?
During the test, your partner or a companion can accompany you in the ultrasound room; they also provide morale and support during the blood sample collection process. Especially in ultrasound sessions with NT measurement, your partner can watch the images together and share this special moment. In accordance with our clinical protocols, we may relax our companion rule according to hygiene and pandemic conditions—you can call us for details.
Is a Double Screening Test Necessary?
Although it is not a legal or medical obligation, the double screening test is strongly recommended for expectant mothers over the age of 35 and those with a family history of genetic diseases. It is included in the standard screening panel by many centers because it provides early diagnosis in low-risk pregnancies and allows the detection of anomalies in advance. The decision is a conscious decision to be made between you and your physician; we are always with you to guide you to the most appropriate options.