NIPT – Non Invasive Prenatal Test

NIPT – Non Invasive Prenatal Test

NIPT is a Non-Invasive Prenatal Test (NIPT) performed on maternal blood to screen pregnancies for the most common fetal chromosome anomalies: trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), trisomy 13 (Patau syndrome) and sex chromosome abnormalities. It can also screen for some common microdeletions syndromes and triploidy.

Who should consider having NIPT?

1.    NIPT can be performed in all pregnancies without specific indication as it has a higher sensitivity than combined screening done by fetal NT scan and biochemical double marker test.

2.    Early gender detection for medical reasons or according to the request of the parents.

3.    Intermediate risk detected by first trimester combined screening.

4.    High risk detected by first trimester combined screening if the couple decline invasive test. However, invasive test is the most appropriate test to be done in such condition.

5.    Advanced maternal age above 35 years old as we require more sensitive test with increased risk for chromosomal anomalies caused by advanced maternal age

6.    Some soft tissue marker anomalies detected in the morphology scan.

7.    In case of high risk screening detected by triple or quadruple marker test in the second trimester.

8.    Anxious mother or parents.

9.    Twin pregnancy to detect the zygosity and risk for major common chromosomal anomalies or common microdeletions syndromes concerning this pregnancy as well as fetal gender(s).

1. History of previous pregnancy with accidental (de novo) chromosomal anomaly.

What is the detection rate for NIPT?

Most NIPT tests have a >99% detection rate for Down syndrome and a false positive rate below 1%. Its sensitivity for other common chromosomal anomalies or common microdeletions range from 95-99%

How early in my pregnancy can I have NIPT?

Most NIPT companies provide the test from 9-10 weeks gestation. An ultrasound scan must confirm the gestation prior to the test.

How long until I get a result?

NIPT takes around 10 working days from sample collection to receiving the report.

Does NIPT replace the need for my nuchal translucency (NT) scan at 12 weeks or morphology scan at 21 weeks?

Definitely not. The NT scan is important for assessing physical anomalies as well as providing a screening assessment for trisomy 13, 18 & 21. The morphology scan is a detailed organ scan which is mandatory at 21 weeks.

What does NIPT involve?

A blood sample from the mother and a brief consultation with our genetic counselor who can answer all your questions.

Can I have NIPT with an IVF or twin pregnancy?

At least one of the NIPT companies can offer this test for twins and IVF pregnancies.

When is NIPT not advised?

When there are fetal major anomalies on the ultrasound or when there are known genetic conditions that cannot be diagnosed by NIPT. Invasive prenatal test is the recommended test in this condition.

In case of vanishing twin or empty gestational sac as NIPT will have a higher rate of false positive results.

Will I find out the sex of my baby with NIPT?

NIPT will report on the gender of your baby if you request this service. There is no extra cost.

Follow up procedure after NIPT

1.    Normal NIPT result – no specific follow up is necessary however if an ultrasound examination of the fetus reveals anomalies then further testing might be recommended.

2.    In case of a test failure – in a small number of pregnancies (<4%) not enough fetal DNA can be extracted from the maternal blood, and NIPT cannot be performed. A repeat sample may be requested at no extra cost.

3.    Abnormal NIPT result – A consultation with our genetic counselor is recommended to discuss the implications of the chromosomal abnormality with the patient. Due to the possibility of a false positive result we recommend confirming a positive result with invasive testing (CVS or amniocentesis).

Dr. Azza Abd El Moneim Attia Mohamed

French Board

Consultant Clinical Genetics