The lowest-risk, highly reliable, however still rather expensive test to assess the individual risk for trisomy 21 (Down syndrome), trisomy 13 and 18 is completed by taking a blood sample from the mother.
This blood sample containing the chromosome fragments must not be taken before the 12th week of pregnancy.
Nuchal translucency ("nuchal translucency"), NT measurement
The images on the right show a sonographic measurement of nuchal translucency (physiological fluid accumulation in the fetal neck) in the 11th-14th week of pregnancy.
A thickened nuchal translucency indicates an increased risk for trisomy 21, 18, 13, and various malformations. The additional determination of other parameters from the blood as PAPP-A (pregnancy associated plasma protein A) and free beta-hCG from maternal blood can increase the detection rate of chromosomal abnormalities.
A safe prediction of individual terms of a genetic malformation is therefore not possible - it is merely a statistical statement.
Compared to the previous method, amniocentesis, where 15-20 ml amniotic fluid is aspirated under ultrasonographic control, is a very reliable chromosomal diagnosis. Its result for Trisomy 21, 18, 13 can be obtained by FISH (fluorescence in situ) within 24 hours. The risk of spontaneous abortion caused by the amniocentesis on the other hand lies at approximately 1:250 – 300.
3D/4D-Sonography in Obstetrics
What is the clinical significance of this technology?
For parents, the striking sculptural 3D images of the face of the unborn child are impressive. They support the prenatal parent-child relationship, as they give a very lifelike impression of the unborn child.
The display of 3D images in real-time format, the so-called real-time 3D or 4D ultrasound allows the study of complex fetal movement patterns.
Particularly important is the real-time display of the fetal heart. This makes it possible to win a spatial impression of cardiac anatomy on a beating heart.