NIPT Test: Down Syndrome Screening, When to test

Choose the content to read

• Why NIPT test?
• Who should do a NIPT test?
• What is the NIPT test screen for?
• What is the NIPT test procedure?
• What does the NIPT test result mean?
• What are the benefits of the NIPT test?
• NIPT Test at MedPark Hospital

NIPT Test

NIPT test (non-invasive prenatal testing) is a blood test that screens chromosomal abnormalities in a fetus using a mother's blood to find the risk of Down syndrome, genetic diseases, and fetus gender screening. NIPT analyzes cell-free DNA fragments circulating in the mother's blood at 10 weeks of pregnancy to detect chromosomal abnormalities after pregnancy as well as to assess the risk to the fetus and screens for the number of extra or missing chromosomes that cause genetic disorders, including Down syndrome, Edwards syndrome, or Patau syndrome. NIPT test is safe, poses no risk to the fetus, and has 99% accuracy in detecting chromosomal abnormalities and the gender of the fetus.

Why NIPT test?

Trisomy 21 is a major cause of Down syndrome, which causes newborn babies to have lifelong intellectual disabilities, delayed development, and distinct physical and facial features from other children. Trisomy 21 also causes abnormalities in various body systems, including the digestive system, congenital heart defects, or thyroid hormone deficiency. NIPT test can detect trisomy 21 in the fetus in the mother's womb as early as the 10th week of pregnancy, assisting in identifying and confirming Down syndrome accurately.

Additionally, 2 of the 3 most common chromosomal abnormalities in a fetus are Trisomy 18, which causes Edwards syndrome, and Trisomy 13, which causes Patau syndrome, which results in miscarriage or possible death after birth, as well as congenital abnormalities or disabilities, including cleft lip and cleft palate or limb disability.

Who should do a NIPT test?

NIPT test is suitable for all pregnant women who are 10 weeks pregnant or more, particularly those with all types of high-risk pregnancies, including:

• Pregnant women aged 35 or above or younger than 17 years who are at high risk of chromosomal abnormalities.
• Pregnancy from in vitro fertilization (IVF/ICSI), surrogacy pregnancy, or twin pregnancy
• Fathers or mothers with a history of themselves or family members having chromosomal abnormalities or previously having had children with genetic diseases.
• Mothers with a history of more than 2 miscarriages due to chromosomal abnormalities or unknown causes.
• Parents who want to know the risk of pregnancy with Down syndrome or other genetic diseases.

What is the NIPT test screen for?

NIPT test screens for chromosomal abnormalities, detecting extra or missing chromosomes that cause the following disorders:

• Down syndrome: extra chromosome 21 (Trisomy 21)
• Edwards syndrome: extra chromosome 18 (Trisomy 18)
• Patau syndrome: extra chromosome 13 (Trisomy 13)
• Jacobsen syndrome: partial loss of chromosome 11
• Turner syndrome: missing 1 sex chromosome (X)
• Klinefelter syndrome: extra sex chromosome 23 (XXY)
• Triple X syndrome: extra sex chromosome 23 (XXX)
• Microdeletions: partially missing fetal chromosome
•      Genome-wide aneuploidy detection to look for missing or extra of other 19 chromosome pairs 

What is the NIPT test procedure?

1. The medical staff cleans the pregnant mother's elbow joint before using a needle to draw 8–18 cc of blood. The blood will be drawn into a collection tube and sent to the hospital's medical laboratory for the fetus's chromosomal analysis.
2. The geneticist uses Next Generation Sequencing (NGS) technology with 99% high sensitivity to analyze the fetus's cell-free DNA circulating in the mother's blood, resulting in accurate, fast, and precise tests.
3. Once the chromosome analysis is completed, the geneticist will send the NIPT test results indicating the total number of chromosomes and details of the shape and completeness of the chromosomes, including the fetus's sex chromosomes, to the doctor to summarize the test results and inform the pregnant mother to plan healthy pregnancy care suitable for each individual.

What does the NIPT test result mean?

The NIPT test result can be interpreted as follows:

Low risk

The fetus has a low probability of chromosomal abnormality.

High risk

The fetus has a high probability of chromosomal abnormality. The doctor will advise on additional specialized tests such as amniocentesis or chorionic villus sampling (CVS) to confirm the test results.

Inconclusive

The test results are unclear and inconclusive due to insufficient fetal DNA in the mother's blood sample. Alternatively, the pregnant mother may have certain diseases or conditions, such as autoimmune diseases or obesity, or a twin or triplet pregnancy, which may cause the test to be misinterpreted. The doctor will collect blood samples for retesting to obtain conclusive results.

How accurate is the NIPT test?

NIPT test is a chromosomal abnormality screening that is regarded as 99% highly accurate and has a low rate of false-positive results, particularly for trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), and trisomy 13 (Patou syndrome). If the test result indicates “high risk,” there is a high probability that the fetus will have chromosomal abnormalities that cause genetic disease, the risk of miscarriage, or neonatal death (death after birth). The doctor will perform additional diagnostic tests to confirm the test result.

How long does it take for the NIPT test result?

NIPT test takes approximately 5-7 days to get the test results. Only some cases may take up to 2 weeks, depending on each individual's factors.

What are the benefits of the NIPT test?

• No Risk: NIPT is highly safe for chromosomal abnormalities screening and poses no risk to the fetus. The test only requires a blood sample from a 10-week-old and above pregnant mother.
• High Accuracy: NIPT is highly accurate and sensitive in detecting fetal chromosomal abnormalities. The American College of Medicine Genomics (ACMG) and the American College of Obstetricians and Gynecologists (ACOG) recommend all pregnant women, regardless of age, have a NIPT test to check for the fetus’s chromosomal abnormality.
• Earlier Results: NIPT looks for chromosomal abnormalities in the fetus and can be screened as early as the first 10 weeks of pregnancy, with results available within 1-2 weeks. NIPT is an effective test and can start screening earlier than other types of tests.
• Gender Screening: NIPT can screen the fetus' gender chromosomes faster than other screening methods, such as ultrasound scans, which can clearly determine the baby's gender at 18 weeks of pregnancy. NIPT can determine a baby’s gender with an accuracy of up to 99%.
•      Plans for Long-term Health: If the fetus has a chromosomal abnormality, NIPT aids in the early detection of abnormalities, enabling doctors to plan systematic treatment early and allowing parents to prepare to care for their baby's health while they are still in the womb.

NIPT Test at MedPark Hospital

Obstetric & Gynecology Clinic, MedPark Hospital, Bangkok, Thailand, is led by a team of medical geneticists with extensive experience in chromosomal abnormalities, genetic testing, DNA sequencing of genetic disorders, and rare diseases, in close collaboration with a geneticist team in the ISO 15189 and ISO 15190 certified clinical laboratories to screen for chromosomal abnormalities and interpret complex genetic sequences, using state-of-the-art Next Generation Sequencing (NGS) technology, aiding in accurate, rapid, and precise test results, leading to effective and systematic pregnancy planning, allowing pregnant mothers a smooth and safe pregnancy, enabling their babies to consistently receive excellent care and attention, while minimizing the risk of complications to the greatest extent.