How is the screening done
As mentioned above, this is a combined examination, which means that it includes several acts. The first act is the collection of blood from a vein in the mother (this is only part of the invasive character.), which is done in the period between the ninth and twelfth week of pregnancy.
Followed by the actual screening – an ultrasound examination. The patient is lying on her back, the doctor passes over her stomach with a probe, while watching the results, which is displayed on a monitor connected to the computer. The most important part of a screening test is measurement of nuchal translucency, carried out between the 12th and 14th week of pregnancy, when is done a check of the length of the fetus, its organs and limbs and further controls the amount of amniotic fluid.
An integral part of the first trimester screening is then personal history, within which are also detected a risk that could endanger the fetus, such as the fact that a woman in labor smokes, uses drugs, drinks alcohol, belongs to a group with a higher average age, etc.
After performing a blood sampling, ultrasound and personal history then the result of combined screening is done. But before we move on to the actual interpretation of the results, we importantly consider clarifying the concept of Down syndrome.
Down syndrome is an inherited disease caused by a chromosomal disorder – specifically an extra copy of the chromosome 21 and it may have a three form (nondisjunction, translocations and mosaic) with varying degrees of severity and incidence in the population. Merkmaly, that point to an increased risk of Down syndrome with nuchal translucency measurement are as following:
- Larger amounts of fluid behind the fetal neck
- Absent nasal bone
- Shorter femur
- Heart defects
A child with Down syndrome (DS) is born with a mental disorder (have lower intelligence quotient) and a striking physical feature, such as a particularly poor muscle tone, small ears, eyes, curving upward into the eye corners, flat neck and nose, short neck and small hands with short fingers. More than half of newborns with DS suffers from heart disease. Treatment options of DS, unfortunately, are not known, as well as reliable prevention.
Interpretation of screening results
The positive results of the first trimester screening certainly does not mean that the unborn child was bound to suffer from congenital defect, only inform the higher the probability of this risk. For these results, the physician outlines a further method, usually the sampling chlorine villi, which is invasive examination, which is performed by collection of the tissue sample from the placenta, in order to identify possible chromosomal effects. The advantage of this method is high reliability. Disadvantage is an increased risk of miscarriage. Another method is amniocentesis, which is also associated with a risk of miscarriage.
Screening as a diagnostic tool
The first trimester screening is a modern combined method of ultrasound diagnostics, which allows you to determine the degree of risk that the unborn baby (fetus at this stage) will suffer from congenital defect. These defects may have nature either anatomical variations or chromosomal defects in the fetus. The best known and most feared of congenital defects is Down syndrome.
The big advantage of this method is its primarily non-invasive nature (unlike amniocentesis), which has its importance, both in terms of eliminating distortions of fetal development, and patient comfort – future mother.CHCI SE OBJEDNAT