Obstetrics

Noninvasive prenatal testing (NIPT)

Non-invasive prenatal testing (NIPT) is a relatively new method of prenatal screening for genetic abnormalities that has entered widespread clinical practice in recent years.

NIPT is based on the fact that, during pregnancy, a certain amount of cell-free DNA fragments of placental origin enters the mother's circulation.

Through modern laboratory methods, these fragments of placental DNA can be correctly identified and analyzed. Since usually the fetus and the placenta have the same genetic material, it is essentially a fetal DNA analysis.

It is recommended that NIPT be performed after 10 w.g. Before this gestational age, the amount of fetal DNA obtained is often insufficient. The ratio of fetal DNA obtained to the total amount of cell-free DNA in maternal serum is called the fetal fraction. With a fetal fraction below 3-4%, it is assumed that NIPT is uninformative and a repeat blood sampling is required, resp. repeating the study.

The main advantages of NIPT are:

NIPT is a significantly more accurate method of prenatal screening compared to ultrasound and biochemical serum screening for Down syndrome, regardless of the period of examination (first or second trimester);
NIPT has a non-invasive nature (the pregnant woman gives a blood sample), therefore it cannot cause a miscarriage unlike invasive methods of prenatal diagnosis (chorion biopsy and amniocentesis);
NIPT results are available within 10 days after the blood sample is taken.

The main disadvantages of NIPT are:

NIPT is relatively expensive and is not covered by the NHIF;
In some cases, the amount of fetal DNA is insufficient (the fetal fraction is small). This is usually seen in early gestation or in overweight pregnant women and requires a repeat blood draw. The presence of a small fetal fraction has been shown to be associated with an increased risk for an associated chromosomal abnormality and warrants careful diagnostic work-up;
Although rare, a positive NIPT result can be a false positive. This is due to a specific condition called placental mosaicism. In these cases, the placenta and the fetus have different genetic material (rather than the same, as is normal). For this reason, any positive result after NIPT requires mandatory invasive prenatal diagnosis (chorion biopsy or amniocentesis) at the discretion of the attending obstetrician-gynecologist.

For more information about the possibility of performing NIPT at MC MARKOVS, you can contact your doctor or call at the registration desk.