Frequently asked questions
Who can request NIPT?
We accept NIPT requests from the following healthcare practitioners:
• A medical practitioner who is accountable for the care provided to a pregnant woman
• A midwife or other allied health professional working as part of a team in which a nominated medical practitioner is accountable for the care provided to an individual patient.
We do not accept test requests from patients themselves, or from clinicians who are not responsible for the woman’s care.
The Australian regulatory authorities stipulate that a genetic test for medical purposes can only be requested as part of a medical consultation. This requirement prevents us from accepting NIPT requests from non-medical healthcare professionals who are working independently, such as independent practising midwives and allied health professionals.
Which patients should be offered NIPT?
NIPT represents a choice that an informed woman may select to provide her with additional information regarding her pregnancy. There are four ways in which NIPT can be included in the management of pregnancy:
- NIPT can be reserved for women with a relatively high chance of having an aneuploid fetus on the basis of conventional first trimester screening. For chromosome abnormalities covered by the NIPT, it is a safe alternative to invasive chromosome testing by amniocentesis or CVS. This approach provides efficient use of NIPT (not all women will have the test), but it is limited by the overall accuracy of first trimester screening. In other words, this strategy will fail to identify some abnormal pregnancies because of the limitations of first trimester screening.
- A second strategy is to offer NIPT to all pregnant women in conjunction with the 12-week scan. The combination of tests has a very high accuracy for detecting fetal aneuploidy and provides a general overview of fetal structure. This strategy is more expensive overall as NIPT is offered to all pregnant women, without prior triaging.
- A third strategy is to offer all pregnant women both conventional first trimester screening and NIPT. The combination of tests has a very high accuracy for detecting fetal aneuploidy, as well as providing a more general screen of fetal structure and biochemical function. This approach is more expensive overall as a woman is being offered NIPT irrespective of the result of conventional first trimester screening.
- The fourth strategy is described as “contingent screening”, and is hybrid of the first two strategies. The principle is that a woman has conventional first-trimester screening. If she is at high risk of fetal aneuploidy, she is offered invasive genetic testing by amniocentesis. If she is at moderate risk of fetal aneuploidy, she is offered NIPT. If she is at low risk of fetal aneuploidy, further testing is not medically warranted. The definitions of what constitutes high, moderate, and low risk of aneuploidy remain matters of debate and analysis. These parameters are not dictated by Sonic Genetics.
We recommend that general practitioners align their NIPT practice with that of the obstetric referral services they use.
When should NIPT be done?
We recommend that NIPT be done between 10 and 14 completed weeks gestation.
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.
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.
Does NIPT require a special request form?
We require a special request form to ensure that we obtain the required information to interpret the analytical result correctly. We will not process a request for NIPT unless the special request form is received and signed by both the referring clinician and the patient.
How much does NIPT cost?
There is no Medicare rebate for NIPT.
Private health insurance does not cover the cost of NIPT.
We charge a private fee for NIPT.
The price is $425 for the standard screen for trisomies 21, 18 and 13.
On request, we can assess the sample for fetal sex or sex chromosome abnormalities (or both) at no additional charge. These options must be requested prior to sample collection.
On request, we can also assess the sample with genome-wide NIPT i.e. for duplication/deletions and for rare monosomies and trisomies. This incurs an additional fee of $70. These options must be requested prior to sample collection.
There is no additional charge for the trisomy screen or any of the options in a twin or IVF pregnancy. However, please note that screening for sex chromosome abnormalities is not available in twin pregnancies.
Payment is required from the patient prior to collection of the NIPT blood sample unless there is a corporate agreement in place with Sonic Pathology Australia. Please click here if you would like to discuss a corporate arrangement.
How long does it take to get a result?
The turnaround time for our NIPT is approximately 3–8 business days from receipt of specimen into the laboratory.
On rare occasions, further analysis of the sample may be required before a result can be issued; in some of these instances, a repeat blood collection and analysis (at no additional charge) may be recommended.
What chromosome disorders are detected by Sonic’s NIPT?
Sonic’s 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 (option)
- duplications or deletions of chromosome segments larger than seven million base pairs, and monosomies and trisomies of chromosomes other than 21, 18, 13 X and Y (option).
Further information about these options are available here.
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 Sonic’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 Sonic’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.
Can NIPT be incorrect?
In approximately 1:2,000 pregnancies, the cells of the outer placenta (the cytotrophoblast) have an abnormal number of chromosomes compared to the developing fetus. This can potentially cause a false positive i.e. NIPT identifies a chromosome abnormality in the placental DNA circulating in the mother’s plasma but the baby turns out to be fine. For this reason, a NIPT result that indicates a high probability of a chromosome disorder must be confirmed by invasive genetic testing before making any major decision about the pregnancy.
Conversely, in up to 1% of fetuses with a major chromosome disorder, the placental chromosomes may be normal. NIPT may report that there is no evidence of a chromosome disorder while the developing fetus actually has a chromosome disorder i.e. a false negative result. For this reason, a “low risk” NIPT result that is at variance with firm evidence of a fetal problem e.g. malformation evident on ultrasound, must be reviewed and invasive genetic testing considered.
These false positive and false negative results are due to the biological complexity of pregnancy. They do not reflect a technical limitation of NIPT and will occur with any NIPT assay.
Does NIPT test for familial disorders?
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.
Should conventional first trimester screening still be done?
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.
The choice and sequence of screening tests used in early pregnancy is a matter of clinical judgement. Sonic Genetics recommends that non-specialist practitioners align their antenatal screening practice with that of their preferred specialist obstetric service.
Should an ultrasound be done before NIPT?
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.
Does NIPT detect DNA from previous pregnancies?
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.
Does the NIPT sample collection require special preparation or booking?
There is no need for the patient to fast, avoid specific medications or avoid intercourse.
However, there are suggestions that exercise may increase the level of maternal DNA fragments in a blood sample, thereby suppressing the proportion of DNA fragments from the placenta; we recommend that the patient be physically rested prior to the blood draw.
The sample collection for NIPT does need to be booked in advance. When the patient has a completed test request form, she can either:
- arrange payment and booking online through the Sonic Genetics payment portal (www.sonicgenetics.com.au/patient), or
- call Sonic Genetics on 1800 010 447 to nominate a convenient collection centre, arrange a time for collection and to pay for the test.
A directory of collection centres available to collect NIPT samples is available on our website.
Sonic has many collection centres in every State and Territory, but not all of these are suitable to collect this test and will not carry the special tubes required. For this reason, we ask that each patient identify the most convenient collection centre that collects NIPT and book a date for collection.
Can NIPT be used for twins and triplets?
NIPT can be used in twin pregnancies provided both fetuses are viable. Please indicate the presence of twins on the request form.
The performance of NIPT for detecting the three common trisomies in twin pregnancies is very good, but not as good as it is in singleton pregnancies. Please note that we cannot offer assessment for sex chromosome abnormalities for twins, and that assessment of fetal sex is limited to “no male twin identified” or “at least one male twin identified”. There is limited experience of genome-wide NIPT in twin pregnancies.
Our NIPT has not been validated in:
- a twin pregnancy with a demised fetus or “vanishing twin”.
- a pregnancy with three or more fetuses.
Can NIPT be used in IVF pregnancies?
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.
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.
Does NIPT detect fetal demise?
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 we do not recommend NIPT 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. We do not recommend NIPT in such settings.
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.
Is genetic counselling recommended?
Sonic Genetics recommends that clinicians refer patients for genetic counselling before or after NIPT according to the patient’s needs and the clinician’s confidence in providing information and support.
If the NIPT result indicates a high probability for a chromosome abnormality, Sonic Genetics offers genetic counselling at no additional cost to the patient. The report will include instructions on how the patient can be referred for this service.
This offer is limited to Australian-based patients who have prepaid Sonic Genetics for their NIPT and to corporate clients (by prior arrangement). Genetic counselling is provided by accredited genetic counsellors. This counselling service is primarily designed to address the information needs of the patient, and does not include further management of genetic testing or the pregnancy. Referrals for the free genetic counselling for NIPT screening must be received within two months of the latest Sonic Genetics report being issued. To access genetic counselling outside this period, or for genetic counselling for other purposes, patients can be directly referred to a genetic counselling provider; a list of potential providers can be found here.
The genetic pathologists at Sonic Genetics are available for discussions with requesting doctors. Our genetic pathologists cannot provide clinical consultations for patients.
Why do some NIPT reports not provide an assessment for a chromosome disorder or fetal sex?
The NIPT assays used by Sonic 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, it may not be possible to provide a very clear answer.
Rather than provide a vague probability of there being a chromosome disorder, we do not report a probability for that disorder. We prefer to not provide an assessment rather than provide an uncertain one. 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.
Is there a refund if the NIPT cannot report on the probability of a specific disorder?
If NIPT is unable to provide an assessment for the trisomies 21, 18 and 13, after the first collection (or after a second collection, if recommended by the laboratory), Sonic Genetics will refund the cost of the test upon request. This refund is limited to patients who have paid Sonic directly and can only be made to the credit card holder. Such patients should contact us on 1800 010 447 to request a refund and advise us of their credit card details that they used to book the test.
We do not provide a refund if the NIPT provides a result for the three trisomies but is unable to provide a result for any of the free NIPT options i.e. fetal sex or sex chromosome abnormality. The primary purpose of Sonic’s NIPT is to detect the three common trisomies. The provision of results for fetal sex or sex chromosome aneuploidies are optional extras for which there is no additional fee.
Can a patient or doctor cancel an NIPT?
Tests can be cancelled by phoning us on 1800 010 447. If the test has not been completed, the test process will be ceased and no result issued.
If the test has been completed, we are obliged to issue the report to the requesting clinician, who is then responsible for the further management of the report.
Depending on the stage at which the test is cancelled, the payment for NIPT may be refunded in part or in full; this is at the discretion of the laboratory, as costs may have already been incurred.
Why are there different types of NIPT?
Over 20 years ago, it was recognised that DNA fragments in the maternal plasma came from both the mother and fetus. Since then, numerous technical strategies have been developed to analyse the DNA and provide information regarding the genetic status of the fetus. Not all types of NIPT are available in Australia, or are provided by an accredited laboratory in Australia. We recommend that doctors request NIPT only from an accredited provider who can provide documentation of the clinical accuracy of the test.
Does Sonic Genetics test for the 22q11.2 microdeletion?
Sonic Genetics ceased offering this option in late 2021.