Also Known As
cffDNA
Formal Name
Cell-Free Foetal DNA Testing for Foetal Chromosomal Abnormalities
This article was last reviewed on
This article waslast modified on 30 October 2017.
At a Glance
Why Get Tested?

To assess the risk of a pregnant woman's developing baby (foetus) having certain chromosome disorders, such as Down’s Syndrome. Following a large, multicentre study in the UK (RAPID study) demonstrating the benefits of the test the UK National Screening Committee (NSC) have recommended NIPT be introduced as an additional test into the existing NHS Fetal Anomaly Screening Programme as part of an ongoing evaluation.

Please see the Antenatal Results and Choices website for more information on accessing the test privately.

When To Get Tested?

Organisations such the American College of Obstetrics and Gynaecology and the International Society for Prenatal Diagnosis currently recommend the test but only in women who are categorised as high risk for having a baby with a chromosome disorder.

The test is most accurate during or after the 10th week of pregnancy.

Sample Required?

A blood sample taken from a vein in the mother's arm. The test is termed “Non-invasive” because obtaining the sample carries very little risk to the mother or baby, unlike procedures such as Amniocentesis and Chorionic Villus Sampling (CVS).

Test Preparation Needed?

None

On average it takes 7 working days for the blood test results to come back from the hospital, depending on the exact tests requested. Some specialist test results may take longer, if samples have to be sent to a reference (specialist) laboratory. The X-ray & scan results may take longer. If you are registered to use the online services of your local practice, you will be able to access your results online.

If the doctor wants to see you about the result(s), you will be offered an appointment. If you are concerned about your test results, you will need to arrange an appointment with your doctor so that all relevant information including age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.), can be considered.

Lab Tests Online-UK is an educational website designed to provide patients and carers with information on laboratory tests used in medical care. We are not a laboratory and are unable to comment on an individual's health and treatment.

Reference ranges are dependent on many factors, including patient age, gender, sample population, and test method, and numeric test results can have different meanings in different laboratories.

For these reasons, you will not find reference ranges for the majority of tests described on this web site. The lab report containing your test results should include the relevant reference range for your test(s). Please consult your doctor or the laboratory that performed the test(s) to obtain the reference range if you do not have the lab report.

For more information on reference ranges, please read Reference Ranges and What They Mean.

What is being tested?

Non-Invasive Prenatal Testing involves looking at cell-free foetal DNA (cffDNA) in the mothers blood. This is genetic material that is released by the placenta and circulates in a woman's blood during pregnancy. CffDNA generally reflects the genetic makeup of the developing baby (foetus). The technology employed in this test detects abnormalities in foetal DNA after it is purified from the pregnant woman's blood.

CffDNA is detectable in a pregnant woman's blood in very small quantities from the later stages of the first trimester. Levels then increase as the pregnancy progresses. .

The test can accurately identify chromosome disorders in a developing foetus, including the presence of extra chromosomes (trisomies) such as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Patau syndrome (trisomy 13). The extra genetic material present in these conditions affects the development of the foetus and causes characteristic signs, symptoms, and complications in later life.

Down syndrome is the most common of the three trisomies detected by NIPT and is a condition that can vary significantly in severity from person to person. Edwards syndrome and Patau syndrome are more rare and more severe, with most affected babies dying within weeks or months of birth. This test may be used to identify other rare conditions resulting from an extra chromosome or missing piece of chromosome (microdeletion).

Non-Invasive Prenatal Testing may also detect an extra sex chromosome if this abnormality is present. One example is Klinefelter syndrome, resulting from two X chromosomes and one Y chromosome. For more on this and other rare chromosome disorders, see the Related Pages tab.

Current routine prenatal testing in the UK includes the first trimester combined screen and the second trimester maternal serum screen. These achieve a detection rate of between 80-90% for Down’s syndrome. Studies have shown that NIPT for cffDNA can be more specific and sensitive than current routine tests in high-risk women, possibly achieving detection rates as high as 99%. It also generates far fewer false positive results.

cffDNA analysis can also be used to identify the blood group of a foetus. This is used to help manage pregnancies where the mother has a particular Rhesus blood type called RhD-negative.

It is important to keep in mind that NIPT is a screening test, not a diagnostic test. If there are abnormal findings in routine prenatal testing or NIPT then more invasive testing, such as chorionic villus sampling (CVS) between 10 and 15 weeks of pregnancy or an amniocentesis procedure between 15 and 20 weeks of gestation, may be required to confirm the diagnosis.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the mother's arm.

The test is often termed “Non-Invasive” because obtaining the sample carries very little risk to the mother or baby, unlike procedures such as Amniocentesis and Chorionic Villus Sampling (CVS).

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

Accordion Title
Common Questions
  • How is it used?

    Non-Invasive Prenatal Testing (NIPT) is a relatively new test that may be used to assess the risk of a pregnant woman's developing baby (foetus) having a chromosome disorder, such as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), or Patau syndrome (trisomy 13). It may be used to identify other rare conditions caused by the presence of an extra chromosome or a missing piece of a chromosome (microdeletion).

    The test involves looking at cell-free foetal DNA (cffDNA), which is genetic material released by the placenta that circulates in a woman's blood during pregnancy. It is detectable in a pregnant woman's blood in very small quantities from the later stages of the first trimester. CffDNA generally reflects the genetic makeup of the developing baby.

    Organisations such the American College of Obstetrics and Gynaecology and the International Society for Prenatal Diagnosis currently recommend NIPT but only in women who are categorised as having a higher risk of having a baby with a chromosome disorder.

    Following a large, multicentre study in the UK (RAPID study) demonstrating the benefits of the test the UK National Screening Committee (NSC) have recommended NIPT be introduced as an additional test into the existing NHS Fetal Anomaly Screening Programme as part of an ongoing evaluation. Plans are also underway to begin offering the test to NHS patients in Wales, Scotland and Northern Ireland.

    NIPT can only be used as a screening test, not a diagnostic test. If there are abnormal findings from routine prenatal testing or NIPT, then more invasive confirmatory testing using procedures such as chorionic villus sampling (CVS) or amniocentesis may be required to confirm the diagnosis.

  • When is it requested?

    Non-Invasive Prenatal Testing is generally only suitable:

  • What does the test result mean?

    A negative NIPT result for trisomy 13, 18 or 21 means that it is very unlikely that the baby has any of these conditions, but other abnormalities may still be present. If the test is positive there is a very high risk that the baby is affected by the identified abnormality but the test is not good enough to say for certain and further invasive testing is required for confirmation i.e. Chorionic villus sampling (CVS) between 10 and 15 weeks of pregnancy or amniocentesis between 15 and 20 weeks of pregnancy.

  • Is there anything else I should know?

    The full range of applications of cffDNA analysis has yet to be established. As research progresses, use of the test may be expanded to many other abnormalities.

    If a woman is tested prior to the tenth week of pregnancy, it is possible to get a false-negative result because of insufficient cffDNA circulating in the mother's blood e.g. low concentration of foetal DNA in the mother’s blood.

    Obesity can lower the concentration of cffDNA in a mother's blood and can mean there is insufficient amounts for accurate testing. Some women may therefore find that they cannot be given a result.

    Rarely, more than one set of genetic information (cell lines) may be present in the placenta, so a trisomy could potentially be present in some cells but not others. This is known as "confined placental mosaicism" and it could affect NIPT results.

     

  • Can I have the Non-Invasive Prenatal Testing in the UK?

    The test is currently only available privately in the UK but research is underway that may lead to routine implementation in the near future. More information about access from within the UK can be found on the Antenatal Results and Choices website

  • Will this test tell me the sex of my baby?

    Yes, this test can reveal the sex of your baby and your healthcare professional may provide you with this information if you request it. However, if you don't want to know the sex of your baby, you can usually request that this information be removed from the test report.

  • Is the test suitable for routine “low risk” screening?

    The RAPID study demonstrated that NIPT is beneficial and cost effective but only when introduced in addition to standard screening i.e. testing after an initial high risk result from existing first or second trimester screening. Whilst the test is highly sensitive and specific it is not currently cost effective for use as ‘first line’ screening test for low risk women. Existing first trimester screening also provides additional information that can be useful in assessing the health of a pregnancy.

  • What else could cell-free DNA testing be used for?

    Cell free DNA originating from many different sources has been identified. Detecting foetal DNA in a mother’s blood is just one application of the technology. Another major area of interest is around the detection and management of some cancers. Research is currently being carried out on the measurement of circulating cell-free DNA (ccfDNA) released into the blood by cancer cells (sometimes called a "liquid biopsy"). Cancer cells and their genetic material are different from normal cells. Most cancers are currently diagnosed by taking a biopsy of tumour tissue and evaluating it under the microscope for characteristic cellular differences. The clinical utility of ccfDNA testing has yet to be fully determined, but it has the potential to help diagnose cancers early using a blood sample to obtain ccfDNA, helping to distinguish between benign and malignant tumors, determine a likely prognosis, and to monitor the effectiveness of treatment.