First trimester scan | Dual test | Combined test

As the name implies, the test is performed between 11 and 14 weeks of pregnancy to determine the risk for certain genetic diseases:

  • Down syndrome
  • Trisomy 21
  • Trisomy 18
  • Trisomy 13

Because it is performed in the 1st trimester (first trimester), it is also known as the “first trimester screening test” or by other names such as “dual test” or “combined test.”

The triple and quadruple screening tests evaluate the age of the expectant mother and the results of some hormone levels in the maternal blood secreted by the placenta, while the dual screening test tries to obtain more accurate results based on some images and ultrasound findings (nuchal thickness NT, presence of the nasal bone, presence of a leaking tricuspid valve, flow of the ductus venosus and forehead-maxillary angle).

On the same day, the expectant mother undergoes a blood test to check the levels of beta-hCG and PAPP-A (pregnancy-associated placental protein A). A special programme then determines the risk for these diseases based on age, weight and data from the test. Depending on the laboratory, the test result is considered positive if this risk is greater than 1/250-1/300.

In addition, at this week of pregnancy, although the organs and systems of the fetus are not fully developed and are still in the developmental stage, the entire body is examined with early detailed fetal sonography. In this way, it is possible to detect about 50% of fetal anomalies at an early gestational age. Nevertheless, a detailed ultrasound examination of the expectant mother and the fetus is performed in the 20th to 23rd week of pregnancy.


Prof. Dr. Ali Gedikbaşı
Contact Information

+90 545 213 5140 - Appointment

Fulya Terrace Center 1
Kat 8 Daire 31,
Hakkı Yeten Caddesi No 11,
Fulya-Şişli, İstanbul

Please publish modules in offcanvas position.