Quadruple test
What is Quadruple test or Quad test?
This is a blood test that is offered to pregnant women who missed their combined screening test( performed between 11-14 weeks) to find out their chance of having a baby with Down syndrome. The test involves checking the blood levels of alpha feto protein(AFP), total human chorionic gonadotropin (hCG), unconjugated estriol(UE3) and Inhibin-A to calculate the risk for Down syndrome.
In pregnancies with Down syndrome, the levels of AFP and UE3 are low, while hCG and Inhibin tend to be high.
How accurate is the Quadruple test?
The detection rate is around 80% for Down syndrome which is less when compared with the combined screening test(90%).
Results between 1 in 2 and upto 1 in 250 is considered as screen positive in which case, diagnostic invasive testing like CVS or amniocentesis is recommended to confirm the diagnosis.
When is Quad test done?
This test is usually performed between 15 to 21 weeks of gestation. It is important to be aware that this test is validated only in singleton pregnancies and therefore not offered to multiple pregnancies. In addition, if the results show higher values of AFP (2 to 3 times over the normal range), there is an increased risk of association with open spina bifida which would need a detailed fetal anomaly assessment by ulltrasound.
Quadruple test for Down syndrome
NIPT
What is Non-invasive prenatal testing (NIPT)?
This is a new type of screening test to check for common trisomies like Down syndrome, Edwards syndrome, and Patau syndrome. It is also called cell-free fetal DNA testing.
We now know that some of the baby’s DNA circulates in the mother’s blood during pregnancy and disappears shortly after birth. DNA is the substance that our chromosomes are made of and contains the genetic information. By separating the baby’s DNA from the mother’s blood, we can identify the risk of the fetus affected with chromosomal conditions like Down syndrome (a common chromosome condition that can cause learning difficulties and physical health issues).
How accurate is the NIPT test?
The test is more than 99% accurate in the detection of Down syndrome with around 97% accurate in detecting Edwards syndrome and 90% accurate to detect Patau syndrome. If the test results are abnormal, diagnostic invasive testing like CVS or amniocentesis is recommended to confirm the diagnosis.
The parents should be aware that there is a small chance that the laboratory is not able to process the sample due to technical issues, low fetal fraction and in around 1 in 300 cases you may get an incorrect result (False positive result). Therefore, if the results of NIPT predicts that the baby has Down syndrome, you will be counselled and offered diagnostic invasive testing like CVS or amniocentesis (please check invasive tests section for further information)
When and how is NIPT done?
NIPT is done by taking a sample of the mother’s blood around 10-11 weeks of pregnancy. "It’s important to know that this blood test is not done in isolation and should always be done in combination with a scan".
Please speak with your Obstetrician or if you require further information, we at Chennai Fetal Care are happy to discuss with you.
NIPT(Noninvasive prenatal testing for Down syndrome)
NIPD
What is Non-invasive prenatal diagnosis (NIPD)?
Non invasive prenatal diagnosis or NIPD is a safe alternative to invasive prenatal testing for conditions like cystic fibrosis, FGFR2 (Craniosynostosis including Apert syndrome) and FGFR3 (Achondroplasia or Thanatophoric dysplasia) related skeletal abnormalities. In addition, bespoke diagnostic services are available depending on risk of baby having a serious genetic condition or a strong family history. These tests are not offered as routine and will be discussed with the genetic laboratory before offering these specialised tests
How is NIPD done?
We now know that some of the baby’s DNA circulates in the mother’s blood during pregnancy and disappears shortly after birth. DNA is the substance that our chromosomes are made of and contains the genetic information. By separating the baby’s DNA from the mother’s blood, we can be able to diagnose the above conditions in the fetus.
NIPD is done by taking a blood sample from the mother which is like a routine blood test and sent to laboratory for analysis. These blood tests are usually performed around 10 weeks with a repeat sample taken a week later.
The turnaround time for results depend on the test requested and will be informed to the couple after discussing with the lab. The results once available, will be informed to the couple with suggested management plan and follow up. A copy of the report with our recommendation and follow up shall also be sent to her doctor for review.
