Combined first trimester screening involves the markers of the ultrasound (popularly called as NT, NB scan) and the blood test- dual marker test. These markers on the scan and the values of the blood test together when combined, provides a risk assessment which tells us that the pregnancy is at high risk or not for genetic abnormalities like Trisomy 21 (Downs syndrome). For risk assessment, we use a software provided by Fetal Medicine Foundation, UK.
The aim is to establish that the baby is alive or not and correctly, establish its gestational age. It involves assessing the baby for gross structural abnormalities. The most important aspect is to assess certain markers like fluid behind the neck of the baby (nuchal translucency), presence of nasal bone, blood flows through heart (tricuspid Doppler) and tummy (ductus venosus) and heart rate.
These markers on the scan and the values of the blood test together provide a risk assessment which tell us that the pregnancy is at high risk for chromosomal abnormalities like Trisomy 21 (Downs syndrome). For risk assessment, we use a software provided by Fetal Medicine Foundation, UK.
It also provides us an opportunity to assess the pregnancies who could be at high risk for developing high blood pressure or weak baby during the course of the pregnancy.
We perform the scan in accordance with the guidelines and the protocol laid down by ISUOG (International Society of Ultrasound in Obstetrics and Gynaecology) and FMF (Fetal Medicine Foundation, UK).
It is done between 11-13+6 weeks.
Ideally, all the pregnant females should be offered combined first trimester screening.
Individuals who perform obstetric scans routinely should have specialized training that is appropriate to the practice of diagnostic ultrasound for pregnant women. We have FMF, UK certificate of competence for NT, NB scan. Our work is audited every year so that we maintain the quality standards as laid down by international organizations. Besides the scan, we will also guide you what is to be done next if a particular abnormality has been detected on the scan.
Prenatal ultrasonography appears to be safe for clinical practice. To date, there has been no independently confirmed study to suggest otherwise.