Non-Invasive Prenatal Testing (NIPT)
Here you will find information about a screening test available in pregnancy called Non-Invasive Prenatal Testing (NIPT). It is used to screen for genetic conditions in your baby.
Most infants are born healthy and have normal development. However a small number will have genetic conditions which may cause disability and have serious consequences. Using ultrasound and maternal blood testing many of these conditions may be detected early in the pregnancy, by the use of non-invasive screening tests.
What is non-invasive prenatal testing?
During pregnancy, some of the baby’s genetic information (fetal DNA) leaks into the mother’s blood. NIPT can detect and analyse fetal DNA circulating in the maternal blood to identify the presence of chromosomal abnormalities and genetic diseases in the fetus. By examining the baby’s genetic material, NIPT can determine if the developing baby has certain chromosomal conditions which can affect health and development. NIPT is performed on the mother’s blood from 9 to 10 weeks of pregnancy and poses no risk to the baby.
What does NIPT test for?
NIPT tests for fetal chromosomal abnormalities. Chromosomes are the packages which contain the body’s genetic material (DNA). Developmental problems occur when there is too little or too much genetic material, or when the genetic material is altered. NIPT tests for condition in the baby where an entire extra copy of a chromosome is present or missing. The most common abnormality screened for by NIPT is Down Syndrome (also called Trisomy 21) which is caused by having an extra chromosome number 21 in each cell of the body. Other less common abnormalities which are screened for are Edward Syndrome (Trisomy 18) and Pataus syndrome (Trisomy 13). NIPT may also be used to screen for sex chromosome variations such as Turners Syndrome (XO), which occurs when there is a missing chromosome in a girl. This test may be done on request and has an additional cost.
Trisomy 21, the most common trisomy, is associated with moderate to severe intellectual disability and may also lead to heart defects and bowel complications in the baby. Trisomy 18 and 13 are associated with higher rates of miscarriage and severe abnormalities, and most affected babies die before or shortly following birth. NIPT will identify over 99% of babies with Trisomy 21, 97% of those with Trisomy 18 and 92% of those with Trisomy 13.
Common reasons for opting for NIPT
NIPT is useful when:
A mother has had a previous pregnancy affected by a chromosomal condition
A mother is aged 35 years or over and at increased risk of having a baby with a chromosomal abnormality
A mother would like more reassurance about her baby’s health without putting the pregnancy at risk by doing invasive testing
An ultrasound indicates a concern with the baby’s growth and/or development. Note that in this case your doctor may recommend an invasive prenatal test be preferable.
How accurate is NIPT?
NIPT is the most accurate screening test currently available and is highly accurate for the chromosome conditions that it tests for. However, the accuracy of the test is not 100% and depends on the maternal age and the chromosomal condition tested for. For example, the result for Down Syndrome may be more accurate than for the other chromosome conditions tested for. There is also the possibility that in a minority of cases, following testing, no results are given. This may be because there is not enough fetal DNA in the mother’s blood, or there is difficulty finding fetal DNA in the mother’s blood. In some instances the sample cannot be processed due to technical reasons. In both instances another blood sample will be taken and tested.
What does a positive test mean?
The test will be reported in one of three ways – Low Risk, High Risk or Not Reported. A low risk result is very reassuring and is highly accurate. With a Low Risk result it is extremely unlikely that the baby has any of the conditions tested for.
If there is not enough fetal DNA detected in the mother’s blood then the test cannot be completed and is not reported (3-8% of cases).
A High Risk result suggest that it is likely that the baby has the genetic condition tested for. However it is important to be aware that this result is not conclusive and that a confirmatory diagnostic test is advised. Diagnostic testing with chorionic villus sampling (CVS) or amniocentesis is recommended in this situation. These are invasive prenatal tests which directly sample the placenta or amniotic fluid cells. They carry a small risk of miscarriage ( 1% for CVS and 0.2% for amniocentesis).
Does a ‘normal’ (low risk) NIPT mean that the baby is healthy?
No test can guarantee that a baby will be healthy at birth. NIPT looks for a number of chromosome conditions including Down Syndrome. NIPT does not provide information on other rare chromosomal abnormalities or structural defects such as heart or spinal cord or brain abnormalities. It is therefore recommended that all pregnancies have an anatomy scan at 20 to 22 weeks’ in the pregnancy to provide further information on fetal structures.
How early in pregnancy can NIPT be used?
Depending on the testing method pregnancies can be screened from as early as 9 (PanoramaÒ) to 10 (PrenatalsafeÒ) weeks of pregnancy.
What if the result of the NIPT shows that the baby might have a condition?
If the NIPT result shows that the baby is at high risk of having a chromosomal condition, the mother will be contacted for a follow up meeting with a Fetal Medicine Specialist. Following this consultation an invasive diagnostic procedures such as chorionic villus sampling (CVS) or amniocentesis will usually be advised, to confirm the diagnosis.
Can NIPT cause harm to mother or baby?
The test uses a sample of the mother’s blood. The mother may experience some discomfort when undergoing a blood test and there is no risk to the baby.
NIPT at The Coombe Hospital
At the Coombe Hospital we provide a weekly NIPT clinic which is available to all women after 9 weeks of pregnancy. We provide both PanoramaÒ and PrenatalsafeÒ tests which are similar but one may be preferable in certain clinical situations. For example PrenatalsafeÒ is used in cases of donor egg, while PanoramaÒ is used where a condition known as triploidy is suspected. In addition the PanoramaÒ test can be performed from 9 weeks of pregnancy while PrenatalsafeÒ can be used after 10 weeks. Neither are suitable in the case of a ‘vanishing twin’.
At the clinic a midwife explains the test, answers any questions and takes consent. The blood test is taken by our phlebotomist and then an ultrasound is performed by a fetal medicine consultant. The ultrasound scan is performed to confirm that the dates are accurate, that the fetus is healthy and to confirm or check for multiple pregnancy.
The test results are available within 10 working days and the midwives or consultant will contact the mother with the result. Follow up is scheduled if required. In some cases a result will not be possible due to a smaller amount of fetal DNA in the sample. This is more common in early pregnancy or where there is increased maternal weight. In this event a repeat blood test will be performed at no extra cost. For most patients, this repeat sample will provide a result. However, in 1% of cases overall a result will not be possible.
Booking details for the NIPT clinic are provided at the end of this information leaflet. Clinics are held on Tuesday evenings from 4pm to 6 pm. Please note that appointments are scheduled on a next available basis and book up quickly.
Fees
There is a fee for the test and ultrasound which is €460 (subject to change; there is no fee for a re-draw), payable in advance. If for any reason a test cannot be performed, the fee will be refunded in full.
Booking Information
Should you wish to book in for an NIPT please provide the following details by email to
Name
Date of Birth
Hospital Number (if known in this pregnancy or from a previous Coombe pregnancy)
Date of your last menstrual period (LMP, first day)
Mobile number (and or landline)
Please note that all correspondence for this screening service is through this email address.