Prenatal Aneuploidy Detection (3 probes - Trisomy 13, 18 and 21) Test
About Prenatal Aneuploidy Detection (3 probes - Trisomy 13, 18 and 21) Test
| Field | Value |
|---|---|
| Also Known As | Prenatal FISH aneuploidy test, Rapid aneuploidy screening, Trisomy 13/18/21 FISH test, Prenatal chromosomal aneuploidy detection |
| Sample Type | Amniotic fluid, Chorionic Villus Sampling (CVS), or cord blood |
| Fasting Required | No fasting required |
| Report Time | 3 days |
| Recommended For | Pregnant women with high-risk screening results, advanced maternal age (35 or older), or other clinical indications |
| Price | Starting at ₹10,300 |
What is a Prenatal Aneuploidy Detection (3 probes - Trisomy 13, 18 and 21) Test?
The prenatal aneuploidy detection test is a specialised diagnostic test that checks for extra copies of chromosomes 13, 18, and 21 in a developing foetus. It uses a laboratory technique called FISH (Fluorescence In Situ Hybridisation), which uses fluorescent probes to identify and count specific chromosomes in foetal cells. The test is also referred to as a Prenatal FISH Aneuploidy test or Trisomy 13/18/21 FISH test. A sample of amniotic fluid, chorionic villus tissue, or cord blood is collected by a trained specialist during the procedure.
What Does a Prenatal Aneuploidy Detection (3 probes - Trisomy 13, 18 and 21) Test Measure?
This test examines three specific chromosomes in foetal cells to check whether an extra copy is present. The table below summarises what each probe targets.
| Chromosome | Condition if Extra Copy Present | Normal Finding |
|---|---|---|
| Chromosome 13 | Trisomy 13 (Patau syndrome) | 2 copies (disomy) |
| Chromosome 18 | Trisomy 18 (Edwards syndrome) | 2 copies (disomy) |
| Chromosome 21 | Trisomy 21 (Down syndrome) | 2 copies (disomy) |
FISH probes bind directly to these chromosomes, making it possible to count them under a fluorescence microscope. The method is greater than 99% sensitive and specific.
Why is a Prenatal Aneuploidy Detection (3 probes - Trisomy 13, 18 and 21) Test Done?
This test is ordered when there is a clinical reason to check for chromosomal abnormalities in the foetus. Below are the common reasons a doctor may recommend it.
Common Symptoms That May Require This Test
The following findings during pregnancy often lead a doctor to recommend the prenatal aneuploidy detection test:
- High-risk result on first-trimester combined screening or a quadruple test
- Abnormal findings on a prenatal ultrasound scan
- Advanced maternal age (35 years or older)
- A previous pregnancy affected by a chromosomal abnormality
- A family history of genetic disorders
- A positive or high-risk result on NIPT (non-invasive prenatal testing)
Conditions This Test Can Help Detect
The test is designed to identify three specific chromosomal conditions:
- Trisomy 21 (Down syndrome): The most common viable chromosomal trisomy, associated with learning disability, congenital heart defects, and other multisystem involvement
- Trisomy 18 (Edwards syndrome): Associated with heart defects, craniofacial abnormalities, growth restriction, and significant developmental impairment
- Trisomy 13 (Patau syndrome): Associated with incomplete brain division, congenital heart disease, craniofacial abnormalities, and central nervous system malformations
Prenatal Aneuploidy Detection (3 probes - Trisomy 13, 18 and 21) Test During Pregnancy
Chromosomal abnormalities can affect any pregnancy, which is why screening is offered to all pregnant women. This prenatal aneuploidy detection test is a diagnostic (not a screening) test, meaning it provides definitive results rather than a risk estimate. It is typically performed after a high-risk screening result and gives rapid, reliable information about chromosomes 13, 18, and 21.
How to Prepare and What to Expect
The preparation steps depend on which sample collection procedure your doctor recommends. Here is a clear overview of what to expect before and during the test.
Do You Need to Fast?
No, fasting is not required before this test. You can eat and drink as normal before your appointment.
Practical Tips Before Your Test
A few simple steps will help your appointment go smoothly:
- Bring a detailed clinical history, including your symptoms, previous test results, and family history, as this is required for the test
- Attend a pre-test genetic counselling session if offered by your doctor or maternal-foetal medicine specialist
- Inform your doctor about all current medications, allergies, and your Rhesus blood type
- Come to the appointment with a comfortably full bladder, as this helps the doctor locate the baby and placenta on ultrasound
- Arrange for someone to accompany you and drive you home, as you may feel some discomfort after the procedure
Step-by-Step Procedure
The foetal sample is collected using one of the following methods, after which the FISH analysis is performed in the laboratory.
Amniocentesis (Amniotic Fluid Collection):
- Your doctor performs an ultrasound scan to locate the baby and placenta.
- A very fine needle is guided through the abdomen into the uterus under continuous ultrasound guidance.
- A small amount of amniotic fluid is withdrawn. This fluid contains foetal cells. This procedure is usually done between 15 and 20 weeks of pregnancy.
- The sample is sealed in a sterile container and sent to the laboratory under refrigerated conditions.
Chorionic Villus Sampling (CVS):
- The procedure is carried out between 11 and 13 weeks of pregnancy, under ultrasound guidance.
- The skin over the abdomen is cleaned, and a local anaesthetic is given to numb the area.
- A fine needle is passed through the abdominal wall into the chorionic tissue (the tissue surrounding the foetus), guided by ultrasound.
- A tiny piece of chorionic tissue (roughly the size of a few grains of rice) is collected and placed in a sterile container for dispatch to the laboratory.
FISH Laboratory Analysis:
- In the laboratory, fluorescent probes are applied to the foetal cells to highlight chromosomes 13, 18, and 21.
- Two trained technologists independently analyse the cells to confirm results.
- Your report is ready within 3 days.
Factors That Can Affect Accuracy
The following factors may influence the reliability of results:
- Quality and quantity of foetal cells collected in the sample
- Maternal cell contamination of the amniotic fluid sample (occurs in a small number of cases)
- Low-level mosaicism (a mix of normal and abnormal cells) may not always be detected
- Improper sample handling or transport
- Confined placental mosaicism in CVS samples, where placental cells carry abnormalities not present in the foetus
Understanding Your Prenatal Aneuploidy Detection (3 probes - Trisomy 13, 18 and 21) Test Results
Results from this test indicate the number of copies of chromosomes 13, 18, and 21 found in the foetal sample. Always review your results with your doctor or a genetic counsellor.
| Parameter | Normal Result | Abnormal Result |
|---|---|---|
| Chromosome 13 | 2 copies (disomy) | 3 copies (Trisomy 13 / Patau syndrome) |
| Chromosome 18 | 2 copies (disomy) | 3 copies (Trisomy 18 / Edwards syndrome) |
| Chromosome 21 | 2 copies (disomy) | 3 copies (Trisomy 21 / Down syndrome) |
A normal result means the foetus shows no extra copies of these three chromosomes. An abnormal result means an extra chromosome was detected and requires further discussion with your doctor.
These ranges are general guidelines. Your doctor will interpret your results based on your age, health history, and other factors. Always consult a qualified healthcare professional for personalised medical advice.
Results During Special Conditions
Certain situations may affect how results are interpreted:
- Low-level mosaicism involving chromosomes 13, 18, or 21 may not be detected by this test. A follow-up karyotype analysis may be recommended.
- Confined placental mosaicism in CVS samples can occasionally produce results that do not reflect the foetus's chromosomal status accurately.
- A normal FISH result does not rule out chromosomal issues beyond these three chromosomes. Your doctor may order additional tests if clinically indicated.
How to Maintain Healthy Levels
While no specific chromosomal outcome can be influenced by lifestyle, these general steps support a healthy pregnancy:
- Attend all scheduled prenatal appointments and follow your doctor's guidance
- Maintain a balanced diet, stay well hydrated, and take prescribed prenatal vitamins, including folic acid
- Avoid alcohol, tobacco, and recreational drugs throughout pregnancy
Lupin Diagnostics Prenatal Aneuploidy Detection (3 probes - Trisomy 13, 18 and 21) Test Price
The prenatal aneuploidy detection test cost starts at ₹10,300 at Lupin Diagnostics. This test requires a visit to a Lupin Diagnostics centre; home collection is not available for this test. Indicative city-wise prices are listed below.
| City | Approximate Price (₹) |
|---|---|
| BHOPAL | 10300 |
| CHENNAI | 10300 |
| HYDERABAD | 10300 |
| KOLKATA | 10300 |
| NAVI MUMBAI | 10300 |
Disclaimer: Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
Follow these steps to book your prenatal aneuploidy detection test online:
- Select the test on the Lupin Diagnostics website.
- Choose your city and preferred centre location.
- Visit the centre at your scheduled time for sample collection by a trained specialist.
- Receive your report via email or WhatsApp within 3 days.
Frequently Asked Questions
NIPT (non-invasive prenatal testing) is a screening test that estimates the risk of chromosomal abnormalities using maternal blood. The prenatal aneuploidy detection test using FISH is a diagnostic test that analyses foetal cells directly and provides a definitive result. A positive NIPT result is often followed by FISH on an amniocentesis or CVS sample for confirmation.
The sample collection procedure itself (amniocentesis or CVS) typically takes around 15 to 30 minutes, including the preparatory ultrasound scan. The laboratory analysis takes up to 3 days, and your report will be shared via email or WhatsApp once ready.
Most women describe the procedure as uncomfortable rather than painful. Some liken the sensation to mild period cramps. A local anaesthetic is applied during CVS to reduce discomfort. Your specialist will keep you informed throughout.
Both procedures carry a small risk of pregnancy loss. Current estimates put this at approximately 1 in 769 for amniocentesis and 1 in 455 for CVS. These procedures are performed by trained specialists under continuous ultrasound guidance to minimise risk. Discuss the risks and benefits with your doctor before proceeding.
No. This test checks only for extra copies of chromosomes 13, 18, and 21. It does not detect other chromosomal or structural abnormalities. Your doctor may recommend a chromosomal microarray or full karyotype analysis alongside this test for a broader assessment.
Standard karyotyping requires foetal cells to be cultured in a laboratory, which can take 5 to 9 days. The prenatal aneuploidy detection test using FISH delivers results within 3 days, providing important information much sooner and helping to reduce parental anxiety while karyotyping is still in progress.
An abnormal result should be discussed with your doctor and a qualified genetic counsellor as soon as possible. They will explain what the finding means, review it in the context of your ultrasound results and overall clinical picture, and help you understand the next steps available to you.
Prenatal Aneuploidy Detection (3 probes - Trisomy 13, 18 and 21) Test
