Down Syndrome Screening Tests in Pregnancy:
When it comes to screening tests during pregnancy, the first thing that comes to mind is screening for Down syndrome (trisomy 21) (Down screening).
It is a misnomer to call Down syndrome screening tests intelligence tests. Because of this false discourse, mothers experience serious anxiety and fear for their babies until they give birth.
While mothers experience fear during their pregnancies due to the intelligence test discourse, some lawyers cause the same fear to physicians. If pregnant women all over the world know and understand this test as a screening test for Down syndrome, there is no reason why pregnant women in our country should not understand it.
Since the main purpose of thecombined double, triple or quadruple screening tests is to screen for Down syndrome, it is more accurate to call these screening tests direct screening tests for Down syndrome. If the patient refuses this screening, they will know directly what they are refusing.
Legal responsibility: The family may or may not agree to the screening for Down syndrome; if they do not agree, we believe that a note in their file or electronic record would be sufficient. The same recommendation applies to the NIPT test and the detailed ultrasound examination (anatomical examination of the fetus).
An ultrasound performed by an obstetrician or a detailed ultrasound performed by a perinatologist is not a diagnostic test for a chromosomal disorder (e.g. Down syndrome). In particular, detailed ultrasound is a method of examining the baby’s anatomy. If there are serious (major) findings on ultrasound, a diagnostic test (such as amniocentesis) is recommended. In short, misuse of these concepts leads to misperceptions and expectations in society.
Which is the best test for screening for Down syndrome?
Dual combined test: 85%
Triple test: 65
Quadruple test: 80%
NIPT test: 99.5-99.9
These figures are approximate. To screen a population, the sensitivity of the test should be at least 75%.
The ideal test for all obstetricians and gynecologists is the quadruple test because of its low cost and simplicity. For physicians who can measure fetal nuchal translucency by ultrasound, the ideal test is the combined dual screening test (nuchal translucency and maternal PAPP-A + b-HCG), provided that it meets universal standards. Its most important advantage is that it can be performed in early pregnancy (between 11-14 weeks of gestation).
The best screening test is the NIPT test, which can be performed as early as 10 weeks gestation; its only disadvantage for now is its high cost.
Definitive diagnostic methodsfor Down syndrome :
Chorionic villus biopsy (placenta biopsy), amniocentesis (taking a sample of the fluid the baby is in) and cardocentesis (taking blood from the umbilical cord).
If the family wishes, one of these diagnostic tests will be performed according to the week of pregnancy. The risk of fetal loss due to the procedure is extremely low(1 loss in 1500-2000 procedures). In order to perform these diagnostic procedures, there must be a significant anatomical abnormality in the baby or the family must request a definitive diagnosis.
OUR RECOMMENDATION: If there is a risk in double, triple or quadruple screening tests, we recommend fetal DNA/NIPT test as a further test after a detailed anatomical examination of the fetus. However, in case of serious anomalies in the baby (fetus), we recommend one of the definitive diagnostic methods appropriate for the baby’s week.
NOTE: Just as every pregnant woman has the right to a detailed anatomy examination, she also has the right to a fetal DNA (NIPT) test, which is the best Down syndrome screening test.
If a pregnant woman has the best Down syndrome screening test, a fetal DNA test, followed by a detailed ultrasound, she will have made the best decision for her pregnancy; this information should be given to every pregnant woman. We believe that this responsibility lies with the physician monitoring the pregnancy; it is up to the family to decide whether or not to have it done. Once the physician has given this information, the family is now responsible.
Recording this information will protect the physician. At least it should be recorded electronically.