Prenatal Testing
Genetic Screening & Interventions
At BWU, we understand that the journey of prenatal testing can feel overwhelming. Our team is here to provide the support, care, and expertise you need every step of the way. You don’t have to face this experience alone – we are committed to ensuring you feel informed and supported throughout the process.
We offer a comprehensive range of genetic screening options, including NIPT (Non-Invasive Prenatal Testing), Genetic Carrier Screening, CVS (Chorionic Villus Sampling), Amniocentesis, Pre-Eclampsia Risk Screening and FTCS (First Trimester Combined Screening). These advanced tests are designed to provide you with accurate insights into the health of you and your baby, enabling you to make confident, informed decisions. Let us guide you in choosing the best option for your pregnancy, with care and compassion every step of the way.
Screening Services
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NIPT is a screening test that analyzes small fragments of fetal DNA found in the maternal blood to assess the chance of certain genetic conditions in the developing baby. These conditions include (but not limited to):
Trisomy 21 (Down syndrome)
Trisomy 18 (Edwards Syndrome)
Trisomy 13 (Patau Syndrome)
Sex chromosome abnormalities – Such as Turner syndrome (only one X chromosome), Klinefelter syndrome (an extra X chromosome in males), and others.
Microdeletions – Small missing pieces of chromosomes that can lead to specific genetic disorders (like DiGeorge syndrome).
How NIPT Works:
The test is done by drawing a small sample of blood from the mother. Since some of the fetal DNA (called cell-free fetal DNA) circulates in the mother’s bloodstream, the test analyzes this DNA to identify potential chromosomal abnormalities.
The process is non-invasive, meaning it doesn't pose any risk to the fetus, unlike invasive tests like amniocentesis or chorionic villus sampling (CVS)
Advantages of NIPT:
Early detection: NIPT can be done as early as 10 weeks of pregnancy
Accuracy: NIPT is known for being highly accurate
Non-invasive: Unlike amniocentesis or CVS, NIPT carries no risk to the baby or mother.
Early peace of mind: may help parents understand their baby's carrier chances early, allowing them to make informed decisions about next steps.
Limitations:
Screening, not diagnostic: NIPT can only assess the chance of certain conditions, not provide a definitive diagnosis. If NIPT results show high probability, further diagnostic testing (like amniocentesis) may be recommended for confirmation.
Limited scope: While it screens for some common genetic disorders, it doesn’t test for all possible conditions, so it doesn’t replace other prenatal tests or screenings.
May be less accurate in the setting of twins and higher order multiples
In short, NIPT is a highly accurate, safe screening test that helps expectant parents understand the likelihood of genetic conditions in their baby.
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Genetic carrier screening is a type of medical test that identifies whether a person carries a gene mutation associated with certain inherited genetic disorders, even if they do not show any symptoms or have the condition themselves. These conditions are usually inherited in a recessive pattern, meaning a child would need to inherit two copies of the faulty gene—one from each parent—to be affected. If both partners are found to be carriers of the same condition, there is typically a 25% chance with each pregnancy that the child could inherit the disorder.
Genetic carrier screening is available to individuals and couples who are considering, or are, in early pregnancy. Screening allows individuals and couples to determine their chance of having children with an inherited genetic condition and aid in making informed decisions about their pregnancy management.
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First Trimester Combined Screening is a prenatal test that combines blood tests and ultrasound to assess the chance of certain chromosomal conditions, such as Trisomy 21 and Trisomy 18, in the developing fetus. It is used as an alternative to NIPT.
Blood tests are typically performed between 11 and 14 weeks of pregnancy, while the ultrasound is performed between 12-13w6d gestation.
Key Components:
Ultrasound:
Nuchal Translucency (NT) Measurement: During the ultrasound, the technician measures the fluid-filled space at the back of the baby’s neck, known as the nuchal translucency. An increased thickness in this area can indicate a higher risk of chromosomal abnormalities and structural abnormalities, particularly of the heart.
The ultrasound also helps assess the overall development of the fetus and can check for other early abnormalities, including structural issues and issues with the placenta etc.
Blood Test:
A blood sample is taken from the mother to measure levels of specific substances in the blood: pregnancy-associated plasma protein-A (PAPP-A) and free beta-hCG (human chorionic gonadotropin). These hormone levels can provide additional information about the risk of chromosomal conditions.
Abnormal levels of these substances can suggest a higher chance of conditions like Down syndrome or Trisomy 18.
How It Works:
The results of the ultrasound and blood test are combined to calculate the risk of the fetus having certain chromosomal abnormalities.
The combined result gives a 1 in X chance for a specific condition, helping to identify pregnancies that may need further diagnostic testing, such as chorionic villus sampling (CVS) or amniocentesis.
Benefits:
Non-invasive: Unlike diagnostic tests, which involve taking samples of amniotic fluid or placental tissue, combined screening is non-invasive and carries no risk of miscarriage.
Early Detection: The screening is done in the first trimester, offering an early look at potential risks.
Informative: This screening helps provide valuable information for expectant parents, allowing for informed decision-making regarding further testing and preparations for the pregnancy.
Limitations:
Screening, not diagnostic: First trimester combined screening cannot diagnose a condition. Instead, it estimates the risk. For instance, it may indicate whether the baby has a higher or lower chance of a chromosomal abnormality.
False positives and negatives: While the combined screening is fairly accurate, there’s still a chance of false positives (indicating a risk when there is none) or false negatives (failing to identify a problem when one exists). Therefore, abnormal results are often followed by further diagnostic tests.
NIPT has a much lower false positive rate than FTCS and is considered more reliable than combined screening.
Why You Might Need It:
Advanced maternal age: Women over the age of 35 are at an increased risk of having a baby with chromosomal abnormalities.
Family history: If there is a family history of genetic conditions, this test can provide helpful information about the risk.
Previous abnormal screening: If a previous screening or ultrasound raised concerns about the health of the baby, this test can give a more detailed risk assessment.
Overall, First Trimester Combined Screening is an important tool in early prenatal care, providing valuable information about the likelihood of certain chromosomal conditions and helping parents make informed decisions about their pregnancy.
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Pre-eclampsia (PET) screening is an essential part of prenatal care aimed at identifying women at risk for developing this potentially serious condition, which is characterised by high blood pressure and signs of organ damage, most often after 20 weeks of pregnancy.
BWU offers first trimester screening for PET, which includes taking a combination of maternal history, blood pressure measurements, blood tests, and ultrasound assessment of the blood flow to the placenta. Ultrasound plays a key role by evaluating placental blood flow through Doppler studies of the uterine arteries, helping to detect abnormalities that may indicate an increased risk for pre-eclampsia. These measurements are combined with maternal Placental Growth Factor (PlGF) (blood serum marker for pre-eclampsia) and blood pressure readings at time of scan to produce a personalised risk of PET development.
Early identification allows for closer monitoring and preventive interventions, such as low-dose aspirin therapy, to improve outcomes for both mother and baby.
Diagnostic Services
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Chorionic Villus Sampling (CVS) is a prenatal test used to diagnose certain genetic conditions in a developing fetus. It is typically done between 10 and 13 weeks of pregnancy and involves taking a small sample of tissue from the placenta (chorionic villi) for analysis. The placenta shares the same genetic material as the fetus, so this test can provide information about the fetus's chromosomes.
Here’s some important information about CVS in pregnancy:
Purpose:
Genetic testing: CVS can detect chromosomal abnormalities such as Down syndrome (Trisomy 21), cystic fibrosis, sickle cell anemia, and Tay-Sachs disease, among others.
Diagnostic test: Unlike some screening tests, CVS is diagnostic, meaning it can provide a definitive answer.
Procedure:
CVS testing is generally performed at 11-14wks gestation
An initial ultrasound is performed to determine position of baby and placenta and best method of approach
A needle is then inserted through the abdomen to reach the placenta where a small sample is collected for analysis.
The examination takes ~45 minutes, however the actual procedure usually lasts about 10-15 minutes.
CVS may be done under local anesthesia.
Risks:
Miscarriage: The risk of miscarriage after CVS is about 0.5% to 1%, though the exact risk can vary depending on factors such as the skill of the practitioner and the specific circumstances of the pregnancy.
Infection: As with any invasive procedure, there is a small risk of infection.
Injury to the fetus: There is a minimal risk that the needle or catheter could harm the fetus or placenta.
Results:
Timing: Results typically take about 1-2 weeks. In some cases, rapid results are available within a few days for certain conditions like Down syndrome.
Accuracy: CVS is highly accurate for detecting chromosomal abnormalities. However, it does not test for neural tube defects like spina bifida. An additional test, like an ultrasound or blood screening, may be needed for that purpose.
Considerations:
Who should consider CVS: It is typically offered to women who are at higher risk for having a baby with genetic conditions, including those over the age of 35, those with a family history of genetic disorders, or those who have had abnormal results from screening tests like the first trimester combined screening or maternal blood tests.
Counseling: Before undergoing CVS, genetic counseling is often recommended to discuss the potential risks, benefits, and implications of the results.
After the Test:
Recovery: Most women can return to their normal activities after the procedure. Some may experience cramping or spotting, but this usually resolves within a few days.
Follow-up: Your healthcare provider will review the results with you and discuss next steps, depending on whether any abnormalities were found.
CVS is a valuable tool for early diagnosis of certain genetic conditions, but it is important to weigh the risks and benefits with your healthcare provider.
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Amniocentesis is a prenatal diagnostic procedure where a small amount of amniotic fluid—the liquid surrounding the baby in the womb—is withdrawn and tested for genetic, chromosomal, or developmental conditions. It is usually performed later in pregnancy, after 15-weeks gestation.
Purpose:
Genetic testing: Amniocentesis can diagnose chromosomal abnormalities like Trisomy 21 (Down syndrome), Trisomy 18, and other genetic conditions such as cystic fibrosis etc.
Neural tube defects: Amniocentesis may also detect neural tube defects like spina bifida and anencephaly, however general 2D ultrasound has been proven to be accurate in the diagnosis of these conditions.
Fetal lung maturity: In some cases, amniocentesis may be performed later in pregnancy to assess fetal lung maturity if there’s a concern about early delivery.
Procedure:
How it’s done: Under ultrasound guidance, a thin needle is inserted through the mother's abdomen into the amniotic sac to collect a small sample of amniotic fluid, which contains fetal cells.
Duration: The procedure typically takes up to 45 minutes, but the actual fluid extraction only takes a few minutes.
Local anesthesia is used to numb the area where the needle will be inserted, though this is typically just to reduce discomfort.
Risks:
Miscarriage: The risk of miscarriage following amniocentesis is about 0.1% to 0.3%. This risk is lower compared to CVS but still exists because the procedure is invasive.
Infection: Though rare, there’s a risk of infection in the uterus, which could affect both the mother and baby.
Injury to the fetus: There is a very small risk of injury to the fetus, but this is extremely rare, especially with ultrasound guidance.
Preterm labor: In some cases, amniocentesis can trigger early labor, although this risk is very low.
Leaking of amniotic fluid: It’s possible for small amounts of amniotic fluid to leak after the procedure, though this is generally rare and often resolves on its own.
Results:
Timing: Results from amniocentesis typically take 1-2 weeks to come back. However, rapid testing is available for some conditions (like Down syndrome), which may give results within a few days.
Accuracy: Amniocentesis is considered highly accurate for diagnosing chromosomal abnormalities and genetic conditions. It has an accuracy rate of over 99% for detecting conditions like Down syndrome.
Amniocentesis is typically recommended for women who are at higher risk of having a baby with genetic conditions, such as in women:
Over the age of 35.
Who have had abnormal results from screening tests like blood tests or ultrasounds.
With a family history of genetic conditions.
Who have had a previous pregnancy with chromosomal or genetic conditions.
Genetic counseling is often offered before and after amniocentesis to help the parents understand the potential risks, benefits, and implications of the test results.
After the Test:
Recovery: Most women can return to their normal activities after the procedure, though they may experience mild cramping or spotting for a day or two. Resting after the procedure is often recommended.
Follow-up: Your healthcare provider will contact you with the results of the amniocentesis. If any abnormalities are found, further testing or consultation with a genetic counselor may be necessary to discuss options and next steps.
Amniocentesis is a valuable diagnostic tool that provides important information about the health of your baby, especially for detecting genetic conditions and birth defects. It is a highly accurate test, though it carries some risks due to its invasive nature. It is generally considered for women who are at higher risk or those who need definitive answers about their pregnancy. It’s important to have a thorough discussion with your healthcare provider about the risks and benefits before proceeding.
At BWU, we partner with Victorian Clinical Genetics Services (VCGS) for all our diagnostic and screening services. VCGS are Australian owned, leaders in genetic health. For more detailed information about their services, accuracy and result timeframe, please visit their website
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