Non-Invasive Prenatal Test (NIPT)
Illumina VeriSeq NIPT
Scan + Blood test
Option of additional consultation with Dr. Bamfo, Fetal Medicine Specialist
10-14 weeks £550
14+weeks £650
The IILumina NIPT Test for:
Down’s syndrome (T21)
Edwards syndrome (T18)
Patau syndrome (T13)
Fetal sexing
Sex chromosome conditions (optional)
Non-invasive prenatal testing (NIPT) screens for the presence of specific chromosome disorders in the developing fetus. The test analyses fragments of DNA in maternal plasma that have been released from both maternal and placental cells.
NIPT requires a single blood draw, which poses no threat to the fetus, and can be done as early as 10 weeks’ gestation. By analysing the proportions of DNA fragments derived from different chromosomes or chromosome regions, NIPT can screen for the presence or absence of specific chromosome disorders.
NIPT is more accurate than first trimester maternal serum screening and ultrasound in identifying pregnancies with or without these disorders.
SOPHISTICATED, ACCURATE, RELIABLE
The appointment is around 40 minute appointment. You will get a full report and a photo. Results can be from 5 working days but can take up to 2 weeks.
The test is processed by The Doctors Laboratory
More about NIPT - Illumina NIPT
DNA from the fetus circulates in the mother’s blood. Cell-free DNA (cfDNA) results from the natural breakdown of fetal cells (presumed to be mostly placental) and clears from the maternal system within hours of giving birth.
During a pregnancy, cfDNA can be tested to give the most accurate screening approach in estimating the risk of a fetus having a common chromosome condition sometimes called a trisomy. This occurs when there are three copies of a particular chromosome instead of the expected two. The test looks to detect the following conditions:
Trisomy 21 is the most common trisomy at the time of birth. Also called Down syndrome, it is associated with moderate to severe intellectual disabilities and may also lead to digestive disease, congenital heart defects and other malformations.
Trisomy 18 (Edwards syndrome) and Trisomy 13 (Patau syndrome) are associated with a high rate of miscarriage. These babies are born with severe brain abnormalities and often have congenital heart defects as well as other birth defects. Most affected individuals die before or soon after birth, and very few survive beyond the first year of life.
Sex chromosome conditions occur when there is a missing, extra, or incomplete copy of the X or Y chromosomes. The NIPT test with sex chromosome aneuploidy panel option can assess risk for XXX, XYY, XXY (Klinefelter syndrome), and a missing X chromosome in a girl (Turner syndrome).
In addition, NIPT can assess fetal sex. This is optional (no additional cost).
NIPT does not screen for non-chromosome disorders, familial mutations, malformations, fetal growth or fetal viability.
CLICK ON QUESTIONS BELOW FOR MORE INFORMATION
The testing is non-invasive: it involves taking a blood sample from the mother. The pregnancy is not put at risk of miscarriage, or from other adverse outcomes that are associated with invasive testing procedures such as amniocentesis.
NIPT provides fewer false-positive and false-negative results than combined first trimester screening for trisomy 21, 18 and 13.
It is important to note that NIPT is a screening test and does not provide a definitive genetic diagnosis, as NIPT cannot differentiate potential chromosome differences between the placenta and fetus. A definitive genetic diagnosis of the fetus requires cytogenetic analysis of either amniotic fluid or chorionic villus sampling (CVS).
|
Accuracy Accuracy (T21, T18, T13) |
Sensitivity* |
False-positive rate# |
|
Combined first trimester screening |
82% |
1 in 82 |
|
NIPT |
>99% |
<1 in 1,000 |
* Proportion fetuses with trisomy correctly identified by the test as high probability of disorder.
# Proportion of normal fetuses incorrectly identified by the test as high probability of disorder.
NIPT Performance data in a general screening population
|
|
Sensitivity* |
False-positive rate# |
|
Trisomy 21 |
>99.9% (95% CI:97.1%) |
>99.90% (95% CI:99.63%) |
|
Trisomy 18 |
>99.9% (95% CI:91.4%) |
>99.90% (99.64% CI:97.1%) |
|
Trisomy 13 |
>99.9% (95% CI:87.1%) |
>99.90% (95% CI:99.64%) |
The VeriSeq NIPT Solution v2 is not validated for use in pregnancies with more than two fetuses, fetal demise, mosaicism, partial chromosome aneuploidy, triploidy, translocations, maternal aneuploidy, transplant or malignancy. VeriSeq NIPT Solution v2 does not detect neural tube defects. Certain rare biological conditions may also affect the accuracy of the test.
For twin pregnancies, HIGH PROBABILITY test results apply to at least one fetus; male test results apply to one or both fetuses; female test results apply to both fetuses. Due to the limitations of the test, inaccurate results are possible.
A LOW PROBABILITY result does not guarantee that a fetus is unaffected by a chromosomal or genetic condition. Some non-aneuploid fetuses may have HIGH PROBABILITY results. In cases of HIGH PROBABILITY results and/or other clinical indications of a chromosomal condition, confirmatory testing is necessary for diagnosis.
Results will be ready in approximately 2–4 days. Women still can have their 12-week scan for a detailed examination of the fetal anatomy, including measurement of nuchal translucency, nasal bone and other important factors. In this visit, patients can discuss the DNA and ultrasound results with their obstetricians.
On the basis of the NIPT result and the ultrasound findings, a patient can decide whether or not she wants to have an invasive procedure (for example, CVS or amniocentesis).
The report then summarises the screening assessment for each disorder specified by the requesting doctor (see example below).
Example NIPT report
Chromosome Result Recommendation
Trisomy 21 High probability Genetic counselling and additional testing
Trisomy 18 Low probability Review result with patient
Trisomy 13 Low probability Review result with patient
Sex chromosome aneuploidy. Not requested –
Fetal sex Male Review result with patient
A high probability NIPT result should always be confirmed by amniocentesis or CVS before making any decision regarding subsequent management of the pregnancy.
There needs to be enough fetal DNA in the maternal blood to be able to provide a result. If there is insufficient fetal DNA in the sample (which occurs in 2% of cases), another blood sample from the mother may be required. This will be processed in the laboratory at no extra charge.
On rare occasions, NIPT is unable to provide an assessment of the probability of specific chromosome disorders. This usually reflects the complex biology of genetics and pregnancy, and is not due to a failing in the laboratory.
If NIPT cannot provide a specific assessment, it is not worth repeating the NIPT (unless advised by the laboratory). A decision about other tests (maternal serum screening, detailed ultrasound, amniocentesis or CVS) should be based on the doctor’s assessment of all risk factors identified, and may require specialist consultation
Once the mother has taken an independent personal decision that she wants to have the NIPT performed, she will be asked to sign a consent form and her blood sample can be taken from a vein in her arm.
The mother's sample and completed request form need to be sent to TDL Genetics, where the test is performed on the DNA extracted from her blood sample.
NIPT does not provide information on mosaicism, partial trisomies or translocations, or other rare chromosomal abnormalities. If the ultrasound scan shows a high nuchal translucency or other major physical defects such as brain abnormalities, heart abnormalities, the risk for some rare chromosomal defects may be high. In such cases, the mother may choose to have a CVS or an amniocentesis.
The non-invasive prenatal test does not provide information on other physical defects such as spina bifida, or information on fetal growth. It is therefore advisable that the mother has all the usual ultrasound scans during her pregnancy.
Samples must be taken in special tubes provided by the laboratory. These samples must not be refrigerated, but stored at ambient temperature.
TDL Genetics NIPT provides a specific test for the following common chromosome disorders: trisomies of chromosomes 21, 18 and 13 (standard test)
abnormal numbers of X and Y chromosomes (singleton pregnancies only)
These chromosome disorders account for approximately 80% of all chromosome disorders identified at birth. This means that the remaining 20% of the chromosome disorders are not detected by TDL’s NIPT. These other disorders could potentially be identified by invasive genetic testing (amniocentesis or CVS), and this carries a small risk of a miscarriage.
The chromosome disorders that would not be detected by TDL’s NIPT are often associated with abnormal ultrasound features in the fetus. For this reason, NIPT is not recommended as the primary test if there are structural abnormalities noted on ultrasound; invasive genetic testing is the more appropriate investigation.
Combined first trimester screening (maternal serum screening with fetal ultrasound) and NIPT provide complementary information about the fetus. There is overlap in the range of conditions that they detect, and each screening method can identify abnormalities that will be missed by the other. For this reason, some clinicians recommend combined first trimester screening and, subject to the result, NIPT. Others recommend detailed ultrasound and NIPT for all patients.
Yes.
The accuracy of NIPT is dependent on knowing the accurate gestational age and the number of fetuses. In early pregnancy, this is best determined by ultrasound. An early ultrasound can also provide clinically significant information that may require assessment before committing to NIPT e.g. the detection of major malformations or fetal demise. We recommend that a dating/viability scan be performed just prior to sample collection for NIPT.
Useful information can also be gained from the 11-13 week ultrasound (e.g. major structural malformations), even if it is not used to screen for chromosomal abnormalities. The 18-20 week detailed structural scan is still indicated, even when NIPT gives a low risk result.
Yes. NIPT can be used in:
IVF pregnancies using egg or sperm from the couple or donor IVF pregnancies where a surrogate is used.
Please provide details on the request form as this information is important for the test algorithm.
The chromosome disorders detected by NIPT are usually new genetic errors that do not run in families, and have occurred as new events in the developing fetus. NIPT does not provide information about the inheritance of single-gene disorders, such as cystic fibrosis, fragile X syndrome and other familial disorders.
If either partner has a personal or family history of a specific genetic disorder, this should be evaluated in its own right as NIPT is unlikely to be a suitable screening test for that disorder.
If you are pregnant and wish to have screening or it has not been possible to do the standard NHS test or missed your combined or quadruple test then the NIPT would be available if you wish.
It can also provide more information whilst deciding on an option of an invasive test.
It is important to note that NIPT Test does not replace diagnostic tests such as amniocentesis and chorionic villus sample as those tests are 100% detection. You would still have to consider these to exclude a chromosomal condition. If you chose the Harmony test in this situation your obstetrician/fetal medicine doctor or midwife should be aware and have discussed this with you. The NIPT test does not exclude structural conditions and has limitations if the fetus has a structural anomaly.
Before booking an appointment, please ensure that you have discussed the NIPT Test with your doctor or midwife and understood all the implications of the test. This is important as your Healthcare professional would have to interpret and manage any results in the context of your medical and family history. They are also aware of your medical history so if there are any concerns or you are taking medications that may interfere with blood tests, they would be able to inform you. You must be at least 18 years old. You will be contacted by telephone when the results are available. The results will be emailed to you.
We will refer you to your local hospital if the result shows a high probability result.
NIPT may be done at any time after the 10th completed week of pregnancy. However, the usefulness of information obtained after 20 weeks may be limited by other factors, such as the interventions available at later gestations.
NIPT has not been validated at gestational ages less than 10 completed weeks. There may be insufficient fetal DNA present in the maternal plasma to provide a reliable result, and samples under 10 weeks will not be accepted for testing.
What will the results show?
The result may show a low probability or high probability result. A low probability risk means it is unlikely that the baby has Downs syndrome, Edwards Syndrome or Patau’s syndrome.
Any screening has a risk of a ‘false negative’ or being told the risk is low when it is high. However the risk of this happening with the Harmony Prenatal Test is much lower than with conventional Down screening.
If the Harmony test result is high probability, you will need to be referred to your local Fetal Medicine Unit for further counselling and possible diagnostic test (CVS or amniocentesis). We will refer you to your local Fetal Medicine Unit.
We advise you give your result to your obstetrician/healthcare provider or midwife - this is important so that the report will be interpreted by them as they will have full knowledge of your clinical history and family history and arrange appropriate fetal medicine referral if required
FAQ's
Can NIPT be used if the fetus has major malformations?
NIPT is not recommended if the fetus is known to have major congenital malformations.
Malformations could be caused by a variety of chromosome disorders or be non-chromosomal in origin. NIPT provides an assessment for selected chromosome disorders, and in this setting the underlying disorder may be missed by NIPT. The more appropriate genetic investigation may be invasive testing by CVS or amniocentesis with fetal chromosome studies by microarray.
Can the mother’s weight affect NIPT?
There is an inverse relationship between maternal body weight and the concentration of fetal DNA (fetal fraction) in maternal plasma. With increasing body weight, there is an increasing probability that there will be insufficient fetal DNA to provide a reliable result. There is no maternal weight threshold at which we do not recommend NIPT. A woman who weighs 140 kg will, on average, have a fetal fraction that is approximately half that of a woman weighing 70 kg.
This relationship between maternal weight and fetal DNA does not compromise the accuracy of NIPT as we confirm that there is sufficient fetal DNA to produce a reliable result in every maternal blood sample tested. However, this relationship does increase the possibility that we cannot provide a result because there is insufficient fetal DNA.
Can NIPT diagnose cancer in a pregnant woman?
There have been reports of some women having strikingly abnormal NIPT results that seem to be incorrect, i.e. the fetal chromosomes are normal when checked. Some of these women have subsequently been found to have cancer. The abnormal NIPT result reflected abnormal DNA from the cancer in the mother’s circulation rather than abnormal DNA from the fetus.
These are rare events (a handful of instances among millions of women tested). The reliability of NIPT in detecting cancer during pregnancy is not known. We do not recommend NIPT as a method of screening for cancer.
Why do some NIPT reports not provide an assessment for a chromosome disorder or fetal sex?
The NIPT assays used by TDL are designed to provide a very clear indication regarding the probability of the developing fetus having, or not having, a specific chromosome disorder. In more than 99% of women tested, we are able to provide a very clear indication either way.
However, in a small number of instances, we may be unable to provide an assessment for all conditions considered in the test, or for only some conditions.
There are various reasons why NIPT cannot provide a clear answer for one or more of the questions being asked by the requesting doctor:
There may be insufficient fetal DNA present for an assessment about a specific disorder. Some conditions may be harder to resolve than others.
There may be uncommon harmless variations in the DNA from either mother or fetus that interfere with the assessment for a given disorder.
The placenta may have a mixture of normal and abnormal DNA that differs from that of the fetus, making it impossible to provide a confident answer regarding a specific disorder.
Does NIPT detect DNA from previous pregnancies?
No.
NIPT examines DNA fragments from the fetus and placenta that are circulating in the mother’s blood. These DNA fragments last only an hour or so, and are replaced continuously from the placenta throughout the pregnancy. Once the baby has been born, the remaining fragments of the baby’s DNA disappear from the mother’s circulation within a couple of hours. As a result, there are no remaining DNA fragments from the baby that might interfere with NIPT in a subsequent pregnancy.
Do I need to have any other tests?
The Harmony Prenatal Test does not provide information on other rare chromosomal abnormalities. If structural abnormalities are found at a later stage of pregnancy the risk for chromosomal abnormality will need to be reviewed as it may be higher. We always recommend having an ultrasound scans at 11-13 weeks and at 20-22 weeks to examine the fetal anatomy.
By having the harmony test at The Aster Clinic, it is understood that you have been fully informed prior to attending the clinic.
Please note that if an ultrasound scan is performed but we do not proceed to the NIPT or there is no result for the NIPT, the fee for the viability scan will remain.
FAQ's
Does NIPT detect fetal demise?
No.
If the event of fetal demise, fetal DNA can continue to be detected in the maternal circulation for weeks or even months while the placenta remains in situ. NIPT cannot determine whether the fetal DNA has come from a viable or non-viable fetus.
In the event of a demised twin (or “vanishing twin”), the fetal DNA from that twin may compromise the accuracy of NIPT of the surviving twin. Our NIPT has not been validated in the presence of a demised twin, and NIPT is not able to be performed if there is known to be a demised twin at the time of sample collection.
If a woman has different estimated dates for delivery, which one should be used?
The decision about which date is more likely to be correct must be resolved by the doctor responsible for managing the pregnancy. NIPT does not provide any information regarding gestation.
It may be preferable to defer collecting a blood sample for NIPT until a gestation of 10 completed weeks as determined by the later date. In other words, it is usually preferable to err on the side of taking a sample for NIPT later rather than earlier in the pregnancy.
Can the mother’s health interfere with the NIPT result?
The NIPT assay assumes that the mother has normal chromosomes and normal amounts of DNA in her blood. The accuracy of NIPT could be compromised by any maternal condition which fails to meet these assumptions e.g. triple X syndrome, mosaic chromosome disorder, cancer, recent blood transfusion, and bone marrow or organ transplantation. NIPT is not able to be performed in such settings.
Can NIPT diagnose cancer in a pregnant woman?
There have been reports of some women having strikingly abnormal NIPT results that seem to be incorrect, i.e. the fetal chromosomes are normal when checked. Some of these women have subsequently been found to have cancer. The abnormal NIPT result reflected abnormal DNA from the cancer in the mother’s circulation rather than abnormal DNA from the fetus.
These are rare events (a handful of instances among millions of women tested). The reliability of NIPT in detecting cancer during pregnancy is not known. We do not recommend NIPT as a method of screening for cancer.
Why do some NIPT reports not provide an assessment for a chromosome disorder or fetal sex?
The NIPT assays used by TDL are designed to provide a very clear indication regarding the probability of the developing fetus having, or not having, a specific chromosome disorder. In more than 99% of women tested, we are able to provide a very clear indication either way.
However, in a small number of instances, we may be unable to provide an assessment for all conditions considered in the test, or for only some conditions.
There are various reasons why NIPT cannot provide a clear answer for one or more of the questions being asked by the requesting doctor:
There may be insufficient fetal DNA present for an assessment about a specific disorder. Some conditions may be harder to resolve than others.
There may be uncommon harmless variations in the DNA from either mother or fetus that interfere with the assessment for a given disorder.
The placenta may have a mixture of normal and abnormal DNA that differs from that of the fetus, making it impossible to provide a confident answer regarding a specific disorder.
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