Abstract

Currently, prenatal chromosomal abnormality screening is routinely based on first-trimester combined screening. When the result of the screening test indicates high risk for child´s birth with chromosomal pathology, definite diagnosis has to be confirmed by an invasive procedure. A negative aspect of screening is the falsepositive test result, which accounts for about 5% for the first-trimester combined test. This is the consequence of unnecessary invasive procedures with a potential procedure-related loss of normal fetuses. A new method of prenatal chromosomal abnormality screening is cell-free fetal DNA testing in maternal blood, which detects over 99% of Down syndrome cases and test’s false-positive rate is less than 0.1%. Since this test has high specificity and sensitivity it will potentially reduce the need for invasive procedures and proves highly suitable for selecting women who would benefit from diagnostic invasive procedures. There are different possibilities for implementing the new screening method for pregnancy screening. An ideal option would be to test all pregnant women at 10 weeks of pregnancy. A negative aspect of this testing is the high cost of cell-free fetal DNA tests (400-1000 euro). It is considerably higher than the cost of the current screening test and is not covered at present by the Estonian healthcare system.