First trimester anatomy scan with first trimester screening
During this examination, which is carried out between the 13th and 14th week of pregnancy, it is determined whether the child’s organs are laid out normally; at this point, 50% of severe congenital malformations can be ruled out.
In addition, the so-called nuchal translucency is measured, a fluid seam that can be seen in every child in this week of pregnancy and which is usually somewhat broader in unborn babies with various conditions such as congenital heart defects, trisomies, skeletal dysplasias and others. With the help of a computer programme, the individual risk for the presence of trisomy can be calculated from the nuchal translucency, the maternal age and the detection of additional ultrasound markers. This risk calculation becomes even more accurate if two values from the mother’s blood are available (free ß-HCG and PAPP-A). We recommend that you have this blood sample taken about two weeks before the ultrasound appointment, as the values are most meaningful at this time.
In most cases, a low risk is calculated. If the individual risk is very high, it must be decided whether the chromosomes of the child should be examined via a chorionic villus sampling or amniocentesis. These invasive methods can be used to determine whether the child’s chromosomes present the condition. If the risk is slightly higher, the mother can also be tested by taking a blood sample, a so-called non-invasive prenatal test (NIPT). If this test shows the chromosomal condition, it must always be confirmed by an amniocentesis.
Ultrasound alone can detect about 75% of all fetuses with Down syndrome; alongside tests from the mother’s blood, the detection rate increases to 85-90%.
The function of the placenta and the risk of preeclampsia can be assessed by measuring the blood flow to the uterus and the blood values mentioned above. If there are problems, low-dose aspirin can have a positive effect on the development of the placenta, but only if it is started before the 16th week of pregnancy.
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