The prenatal tests comparing

The tests of prenatal screening in the first trimester of pregnancy, such as the measurement of nuchal translucency combined with the two biochemical markers, free-βHCG and PAPP-A, are non-invasive prenatal testing, but have a false positive rate of up to 5% and They do not detect correctly up to 30% of cases of trisomy 21.

These tests can, in fact, bring a positive for fetal trisomy although in fact we are in the presence of a pregnancy with a healthy fetus (false positive) or may bring a negative for fetal trisomy, while in reality we are dealing with pregnancy a fetus with fetal trisomy (false negative).

The prenatal screening tests, such as amniocentesis and chorionic villus sampling, while having a screening reliability of over 99% for all trisomies and fetal aneuploidy, are highly invasive and have a potential risk to the health of the mother and fetus (up to cause the ' abortion).

The following table compares the advantages and the limitations of current prenatal screening test non-invasive and invasive with latest-generation test performed on maternal blood.

Screening tests of the 1st trimester of pregnancy
based on the combination of biochemical markers and ultrasound data (PAPP -A , free β - hCG and NT)
- Maternal Blood Sampling
- Data sonographic
- Secure: extremely limited risk for the mother and the child
- Reasonable costs
Indirect tests on a statistical basis
Multiple visits to screen
Up to 5% of false positives
Up to 30% of false negatives
Amniocentesis - chorionic villus sampling
(Chromosome analysis)
- Removal of amniotic fluid
- Withdrawal chorionic villi
- High screening acccuratezza
- Possibility of cytogenetic or molecular testing
Risk of miscarriage ' (0.5 - 1 % )
Possibility 'of complications for the mother
High cost for the patient and for the health system
Non-invasive test using fetal DNA
First-generation test (shotgun sequencing)
Non invasive:
- Blood sample
- Accurate
- Sicure
High cost for the patient
Limited to the detection of fetal trisomy sun
Harmony Prenatal Test
Direct test DNA
Non invasive:
- Maternal Blood Sampling
- Accuracy > 99 % for Down Syndrome
- Sicure
- Efficient and economical
- Customized quantitative results