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NIPT Information for Patients


Non-Invasive Prenatal Testing (NIPT) for Down Syndrome


What is NIPT?
NIPT (also called NIPS) is a screening test for common genetic conditions in the fetus.  In particular, it can be used to screen for Trisomy 21 (Down syndrome).  NIPT analyses fetal DNA (genetic material) found in the mother’s blood sample to predict if the fetus might be affected.  NIPT can be done as early as 10 weeks of pregnancy.  NIPT testing is done only by specialized laboratories, and is not part of routine screening in Nova Scotia. It is offered to patients who have pregnancies that are at higher risk for Down Syndrome.


What is the difference between a screening test and a diagnostic test?

screening test gives an assessment of risk (high risk or low risk) for a specific condition(s). Screening tests can give results that are falsely positive (a high risk result when the fetus is not affected) or falsely negative (a low risk result when the fetus is actually affected). 
diagnostic testperforms at a level of certainty that is so good that it is felt to give a definite answer (yes or no).
Diagnostic tests for a fetus require a sample from the pregnancy using an invasive procedure, such as chorionic villus sampling (CVS; biopsy sample of the placenta) or amniocentesis (sample of amniotic fluid). These procedures have a risk of pregnancy loss of about 1/200-1/400. 
Screening tests for a fetus are done using blood samples from the mother and ultrasound of the fetus. There is no risk of pregnancy loss by having screening tests for Down syndrome. 
NIPT is considered a screening test and does not perform at a diagnostic level.  NIPT is a blood test from the mother, and therefore has no risk of pregnancy loss. 


How is NIPT different from standard screening tests for Down Syndrome?
NIPT has a performance that is much better than any other screening tests, such as maternal serum testing (MST) and ultrasound tests.
NIPT will detect more than 99% of cases of Down Syndrome; standard screening will detect 75-85% of cases.
NIPT has a false positive rate of 0.3% (only one in 350 women will mistakenly have a high risk result); standard screening has a false positive rate of 3-5% (one in 20-35 women will mistakenly have a high risk result).


Who is offered the option for NIPT?
Patients who have a high risk for Down syndrome in the pregnancy after routine screening and ultrasound assessment will be counselled about this option. These patients will be seen by Medical Genetics or Maternal-Fetal Medicine specialists for counselling about all test options.  For patients who are at increased risk, NIPT will be offered as an alternative to diagnostic testing (CVS or amniocentesis). 


Can I have NIPT even if my pregnancy is not at high risk for Down syndrome?
Patients who are not at high risk for Down syndrome, but want to have NIPT, can pay to have the testing done privately. 
Your health care provider can help you understand your risk, and all options of screening or testing that are available to you.


Before paying for this test, you should understand the limitations:
1. NIPT tests only for the genetic conditions stated; it does not give information about any other genetic conditions in the fetus or family
2. NIPT is a screening test  -

  • a reassuring result does not completely eliminate the possibility of Down syndrome in the fetus
  • a high risk result is very likely to be true, but some of these may be found to be normal when a diagnostic test is done

3. NIPT has a small risk of test failure, and a second sample may be required
4. Performance of NIPT is not as good in twin pregnancies


Speak with your health provider about these limitations before getting NIPT