[Non-invasive prenatal test in the diagnosis of aneuploidy 13, 18 and 21--theoretical and practical aspects]

The incidence of numerical chromosome aberrations is about 5% during the entire pregnancy and about 0.2% in live-born infants. Most commonly observed numerical aberrations in live births are trisomies of chromosomes 13, 18, 21, X and Y and monosomy of the X chromosome. It is estimated that approximately 70-80% of newborns with aneuploidies are born by women who did not present obvious risk factors, therefore, according to a recent recommendation by PTG, prenatal diagnosis increasing the detection of fetal aneuploidy should be offered to the entire population of women. Due to the risk of complications associated with invasive tests and a large number of unnecessarily performed tests of this type, it is postulated that invasive diagnostics should be used in very specific cases, and a non-invasive diagnostics should have a screening character Non-invasive diagnostics include: 1) detailed ultrasonography performed in 11-13 (+6 days) hbd and in 18-24 hbd; 2) biochemical tests: PAPP-A (first-trimester test) and the triple test (second-trimester test) and less frequently performed: double, quadruple, and integrated tests. High detection rate of chromosomal aberrations in non-invasive tests (at least 75%, with no more than 5% risk of obtaining false positive results) and lack of procedure-related pregnancy losses constitute the advantage of noninvasive prenatal diagnosis.