Prenatal tests provide critical information to guide the pregnancy and help plan postnatal care. Conventional karyotyping is performed on CVS (chorionic villus sampling), amniotic fluid and cord blood samples.
Non-Invasive Prenatal Screening (NIPT)
NIPT is a screening method used during pregnancy to detect Down syndrome (trisomy 21), trisomy 18, trisomy 13 and other chromosomal abnormalities in the fetus. Whereas conventional invasive procedures such as amniocentesis or chorionic villus sampling (CVS) carry a risk of miscarriage, NIPT is performed on a simple blood sample from the mother, offering a safer option for mother and baby.
How Is It Performed?
NIPT analyzes small fragments of fetal DNA in the mother's blood and determines whether the fetus has any chromosome number abnormality.
Limitations of NIPT
Although NIPT is highly accurate, it does not replace a diagnostic test. High-risk results must therefore be confirmed with diagnostic testing. The test cannot detect polyploidy, birth defects (such as neural tube defects), single-gene disorders or conditions such as autism. Results may also reflect chromosomal changes in the placenta (confined placental mosaicism, CPM) or in the mother.
Prenatal WES
Prenatal whole exome sequencing (WES) is an advanced genetic test that sequences all protein-coding regions of the genome to identify mutations in cases of developmental abnormality or suspected rare disease. It provides critical genetic information that supports decision-making in high-risk situations and the planning of postnatal care.
Prenatal WES is recommended for
- Abnormal ultrasound findings
- Previous unexplained pregnancy losses
- Parents known to be carriers of a genetic disorder
- Inconclusive results from other tests
- Fetal growth restriction
Prenatal WGS
Prenatal Whole Genome Sequencing (WGS) is a comprehensive genetic test that sequences the entire genome, offering broader coverage than Whole Exome Sequencing (WES) by analyzing both coding and non-coding DNA regions. It is especially useful when conventional tests, including WES, fail to provide a definitive diagnosis. It can identify a wide range of genetic variation, providing valuable information for pregnancy management and postnatal care.
Prenatal WGS is recommended for
- Unexplained abnormalities detected on ultrasound
- Previous unexplained pregnancy losses
- Known family history of a genetic disorder
Prenatal Microarray
Prenatal microarray analysis is a genetic test that detects chromosomal abnormalities at a higher resolution than conventional karyotyping and identifies gains or losses of chromosome segments that may lead to developmental problems or genetic disorders in the fetus.
Microarray is recommended for
- Family history of a chromosomal disorder
- Structural chromosomal abnormalities
- Abnormal ultrasound findings
- Unexplained fetal growth restriction
- Previous pregnancy losses of unexplained cause
Prenatal SNP Array
Prenatal SNP array is a test that uses single nucleotide polymorphism (SNP) technology to detect large and small chromosomal abnormalities such as copy number variations (CNV) and uniparental disomy (UPD) with greater sensitivity than conventional methods.
SNP array is recommended for
- Abnormal ultrasound findings
- Unexplained fetal growth restriction
- Recurrent pregnancy losses