Very early fetal scan
A very early ultrasound examination of fetal developmental defects together with an NIPT-test at the 10th week of pregnancy and combining these studies with the OSCAR test at the 13th week of pregnancy is currently the most accurate combined prenatal screening for the early detection of chromosomal diseases and developmental defects in children.
The ultrasound examination before the NIPT test is carried out whose pregnancy has lasted at least 10 full weeks (10 weeks + 0 days). At this size of the pregnancy, the child's embryonic period is complete and the child has already developed major organ structures that can be assessed by transvaginal ultrasound examination.
The purpose of the ultrasound examination is to specify the size of the pregnancy, to assess the possibility of a twin pregnancy and its type, and to exclude situations in which the NIPT test should not be carried out.
The NIPT test should not be carried out in the following cases:
- Pregnancy duration of fewer than 9 weeks;
- Abortion;
- One of the twins has deceased;
- Significant developmental disorders of the child;
- A thick nuchal fold of the child (NT >3.5 mm).
In 1 of 10 cases, the ultrasound examination before the NIPT test changes the approach to the screening test. The older the mother, the more important it is to do the pre-NIPT ultrasound examination.
- If the size of the pregnancy is fewer than nine weeks, the NIPT test has to be postponed;
- If an abortion has occurred, if one of the twins has deceased, in case of a triple pregnancy or significant developmental disorders of the child, the NIPT test cannot be carried out;
- Vistara test cannot be carried out in case of a twin pregnancy;
- In the case of dichorionic twins, the PanoramaXP test cannot be carried out; in the case of monochorionic twins, only the Panorama 22q11 test can be done;
- If the child's nuchal fold is thicker than 2.1mm, doing the NIPT test straight away is not justified. In this case, the ultrasound examination should be repeated in the 12th gestational week. If the nuchal fold hasn't thickened in the next ultrasound, the NIPT test may be carried out;
- If the child's nuchal fold is thicker than 3.5mm, doing the NIPT test is not justified. In this case, the mother can be offered a chorionic villus sampling, because a thickened nuchal fold could indicate genetic disorders that are not detectable by the NIPT test.
As the NIPT test cannot detect the structural-developmental disorders of the child, the purpose of the ultrasound examination before the NIPT test is to exclude 10 severe developmental disorders of the child:
- Absence of skull bones (1:1,000)
- Absence of cerebral hemispheres (1:1,300)
- Spinal cord herniation (1:2,000)
- Absence of arms, hands, legs, or feet (1:2,000)
- Cerebral herniation (1:5,000)
- Large umbilical cord herniation due to which the liver is located partially outside the body through the navel (1:3,500)
- Amniotic band syndrome (1:7,000)
- Severe defect of the anterior abdominal wall due to which the internal organs have attached to the placenta (1:7,500)
- Sirenomelia, also called mermaid syndrome (in which the legs are fused) (1:60,000)
- Conjoined twins (1% of monochorionic twins)
In the case of previously listed severe developmental disorders of the child, the woman has the right to terminate her pregnancy without undergoing further invasive prenatal procedures. In this case, it would be reasonable to do a chromosomal examination of the aborted fetus after terminating the pregnancy.
Naturally, it is impossible to detect most congenital developmental disorders in the 10th gestational week, when the fetus is 32mm tall and its heart is 4mm big.
To provide a safe course of your pregnancy and confidence in carrying a healthy child, we advise you to combine the very early fetal developmental disorder ultrasound examination and the Panorama test and GeneSafe test with the OSCAR test carried out in the 12th-14th gestational week.
In addition to the screening of preeclampsia and growth impairment, we will carry out an early developmental disorder ultrasound examination for Your child within the OSCAR test. This ultrasound examination can exclude over 100 various developmental disorders.
Video.10 weeks pre-NIPT ultrasound. Dr Marek Šois 2023