How does NIPT work?

NIPT (Non-Invasive Prenatal Testing) is a single blood test that uses a special genetic technology to screen pregnancies for the most common chromosome abnormalities.  It can also inform you of the gender of your baby if desired.  This new test can be completed as early as 10-weeks gestation, with no risk to the pregnancy. NIPT analyzes the DNA in your blood (your DNA as well as fetal DNA) to screen the pregnancy for the following chromosome abnormalities:

  • Trisomy 21 (Down syndrome)
  • Trisomy 18 (Edwards syndrome)
  • Trisomy 13 (Patau syndrome)
  • Sex Chromosome differences such as Monosomy X, Triple X (XXX), Klinefelter syndrome (XXY), and Jacob syndrome (XYY)

Our partnering NIPT labs, Integrated Genetics and Ariosa, provide the analysis called Harmony™.

What conditions can NIPT screen for?

NIPT can screen pregnancies  for Trisomy 13, Trisomy 18, Trisomy 21 and sex chromosome differences. While they are each caused by a missing or extra copy of a  chromosome, they have distinct features. Please contact one of our genetic counsellors if you would like to discuss these conditions further. Alternatively, Genetics Home Reference is a useful resource to learn more about these genetic conditions (https://ghr.nlm.nih.gov/ ). For example, more information about Down syndrome can be found here.

How Accurate is NIPT vs. AHCIP Insured Screening Tests?

 

Chromosome NIPT Detection Rate1 NIPT False Positive Rate1 Insured Screening Detection Rate- First Trimester Screening (FTS)2 Insured Screening Detection Rate- Integrated Prenatal Screening (IPS)2
 21 >99% <0.1% 82 – 87% 95%
18 97.4% <0.1% Not reported Not reported
13 93.8% <0.1% Not screened Not screened

1Norton et al. Am J Obstet Gynecol. 2012 Aug;207(2):137.e1-8; Nicolaides et al. Am J Obstet Gynecol. 2012 Nov;207(5):374.e1-6; Ashoor et al. Ultrasound Obstet Gynecol. 2013 Jan;41(1):21-5; Verweij et al. Prenat Diagn. 2013 Oct;33(10):996-1001; Ashoor et al. Am J Obstet Gynecol. 2012 Apr;206(4):322.e1-5; Sparks et al. Am J Obstet Gynecol. 2012 Apr;206(4):319.e1-9; Gil et al. Fetal Diagn Ther. 2014;35:204-11; Norton M, et al, N Engl J Med. 2015 Apr 23;372(17):1589-97; Harmony data on file; Juneau et al. Fetal Diagn Ther. 2014;36(4):282-6.

2https://myhealth.alberta.ca/health/tests-treatments/pages/conditions.aspx?Hwid=abo6088#abo6095

When are results reported for NIPT vs AHCIP Insured Screening Tests?

NIPT First Trimester Screening (FTS) Integrated Prenatal Screening (IPS)
As early as 10 weeks gestation ~12-15 weeks gestation ~16-21 weeks gestation

When will I receive my NIPT results?

NIPT results typically only take 5-7 days from the day of the blood draw at PCRM and therefore, can be available as soon as 10-11 weeks gestation. One of our genetic counsellors will call you to discuss the results as soon as they are available. We will provide you and your pregnancy care provider with a detailed copy of the report. If any concerns are identified, we will coordinate appropriate follow-up.

What types of results can I get?

  • A low probability result means that the chance of Down syndrome, Trisomy 18 or Trisomy 13 is low (less than 1/10,000 chance). Almost all pregnancies that are unaffected by these chromosome problems will receive a low probability result.
  • A high risk result means that the chance of a chromosome problem is increased. Greater than 99% of pregnancies with Down syndrome, 97% of pregnancies with Trisomy 18 and 94% of pregnancies with Trisomy 13 will be flagged as high risk. A high risk result does not mean that a pregnancy is actually affected. Only definitive testing with CVS or amniocentesis can determine the true presence of a chromosome problem.
  • A no result/re-draw request is uncommon but possible. The rate of no result/re-draw requests is about 2%. Of those who opt for a re-draw, approximately 70% will receive a result. In the rare case a result cannot be obtained for you, a refund will be initiated and appropriate follow-up recommendations will be discussed.

What are the next steps after NIPT?

NIPT is a very targeted screen. NIPT does not replace standard methods of screening including ultrasound evaluation at 18-20 weeks.

Have more questions?

We know that prenatal screening options today can be quite confusing and overwhelming. Our genetic counsellors are available to answer your questions and to discuss the benefits and limitations of NIPT, and insured screening options to determine the best choice for you.

Contact us today:

Email: PCRM-GeneticCounsellors@pacificfertility.ca

Toll Free:  1-866-481-7276