FISH-Prenatal Aneuploidy Detection (5 Probes- Trisomy 13,18,21,X,Y)
About FISH-Prenatal Aneuploidy Detection (5 Probes- Trisomy 13,18,21,X,Y)
| Field | Value |
|---|---|
| Also Known As | FISH Prenatal Aneuploidy Test, Rapid Aneuploidy Screening (RAS), Prenatal FISH 5-Probe Panel, Interphase FISH for Aneuploidy |
| Sample Type | Chorionic Villus Sample (CVS) |
| Fasting Required | No fasting required |
| Report Time | 3 Days |
| Recommended For | Pregnant women at elevated risk for foetal chromosomal abnormalities |
| Price | Starting at ₹10,300 |
What is a FISH-Prenatal Aneuploidy Detection (5 Probes- Trisomy 13,18,21,X,Y) Test?
The FISH-prenatal aneuploidy detection (5 probes- trisomy 13,18,21,X,Y) test is a specialised genetic test performed during pregnancy to check for certain chromosomal abnormalities in the developing baby. FISH stands for Fluorescence In Situ Hybridisation, a technique that uses fluorescent probes to identify and count specific chromosomes in a cell sample. A chorionic villus sample (CVS) is used for this test. It is also known as the FISH prenatal aneuploidy test or Rapid Aneuploidy Screening (RAS).
What Does a FISH-Prenatal Aneuploidy Detection (5 Probes- Trisomy 13,18,21,X,Y) Test Measure?
The FISH-prenatal aneuploidy detection test examines five specific chromosomes using fluorescent probes. Each probe attaches to a target chromosome in the sample, allowing the laboratory to count how many copies are present. The five chromosomes examined are listed below.
| Chromosome | Abnormality Detected | Associated Condition |
|---|---|---|
| Chromosome 13 | Extra copy (3 signals) | Patau syndrome: severe physical and intellectual abnormalities |
| Chromosome 18 | Extra copy (3 signals) | Edwards syndrome: severe developmental problems |
| Chromosome 21 | Extra copy (3 signals) | Down syndrome: most common chromosomal cause of intellectual disability |
| Chromosome X | Reduced or extra copies | Turner syndrome (missing X in females): short stature and infertility |
| Chromosome Y | Abnormal copy number | Klinefelter syndrome (extra X in males, 47,XXY) and other sex chromosome abnormalities |
Why is a FISH-Prenatal Aneuploidy Detection (5 Probes- Trisomy 13,18,21,X,Y) Test Done?
This test is requested when a pregnant woman has a higher-than-average risk of carrying a baby with a chromosomal condition. The FISH-prenatal aneuploidy detection test procedure gives results quickly, which can be important for clinical decision-making.
Common Symptoms That May Require This Test
Doctors typically recommend this test based on specific risk factors rather than symptoms. The following factors commonly lead to a referral.
- Maternal age of 35 years or older at the time of delivery
- Abnormal findings on a foetal ultrasound scan
- Abnormal results from serum screening tests (e.g., high or low levels of certain pregnancy hormones)
- A family history of chromosomal abnormalities
- A previous pregnancy or child affected by a chromosomal condition
- A history of recurrent miscarriages
- High-risk findings from non-invasive prenatal testing (NIPT)
Conditions This Test Can Help Detect
The test is designed to identify five of the most clinically significant chromosomal conditions. Together, these account for the large majority of chromosomal abnormalities diagnosed during pregnancy.
- Trisomy 21 (Down syndrome)
- Trisomy 18 (Edwards syndrome)
- Trisomy 13 (Patau syndrome)
- Turner syndrome (45,X)
- Klinefelter syndrome (47,XXY)
- Other sex chromosome aneuploidies, such as Triple X syndrome (47,XXX)
FISH-Prenatal Aneuploidy Detection During Pregnancy
This test is specifically a prenatal diagnostic procedure performed during pregnancy. CVS samples are typically collected between 11 and 13 weeks of gestation. The test provides rapid information on five key chromosomes, enabling the clinical team and family to make informed decisions about further testing and care. Results are usually available within three days of sample receipt at the laboratory.
How to Prepare and What to Expect
The FISH-prenatal aneuploidy detection test procedure requires a CVS sample, which is collected at a clinical centre under ultrasound guidance. Here is what you need to know before your appointment.
Do You Need to Fast?
No fasting is required for this test. You may eat and drink normally on the day of the procedure.
Practical Tips Before Your Test
Preparation for this procedure involves a few important steps. Please follow these guidelines before attending your appointment.
- Bring a detailed clinical history including your symptoms, previous test results, and family history, as this is required for the test.
- Bring your completed PNDT (Pre-conception and Pre-natal Diagnostic Techniques) Consent Form and Form-G, as these are mandatory legal documents required before the test can proceed.
- Inform your doctor about all medications you are taking, any known allergies, and any bleeding disorders.
- Tell your doctor if your blood type is Rh negative, as this is relevant for managing any potential mixing of maternal and foetal blood.
- Wear loose, comfortable clothing to your appointment.
Step-by-Step Procedure
The CVS procedure is performed by a trained specialist under the supervision of an obstetrician at a clinical centre. The following steps describe what to expect.
- You will lie on your back on an examination table. A gel is applied to your abdomen, and an ultrasound scan is performed to check the position of the baby and placenta.
- The skin on your abdomen is cleaned with an antiseptic solution.
- A thin needle is inserted through the abdomen into the placenta under continuous ultrasound guidance. A small tissue sample (approximately 30 mg of chorionic villus tissue) is collected.
- The needle is removed. The sample is placed in a sterile container and stored at 2 to 8 degrees Celsius for transport.
- The sample is sent to the laboratory, where fluorescent probes are applied to the chromosomes in the cells.
- A specialist analyses the fluorescent signals under a microscope and compiles the report, which is delivered within three days.
Factors That Can Affect Accuracy
Some factors may influence the reliability of the test result. Being aware of these helps set appropriate expectations.
- Blood-contaminated samples may reduce accuracy
- Low-level mosaicism (a mix of normal and abnormal cells) may not be detected
- Confined placental mosaicism in CVS samples, where placental cells differ from foetal cells
- Maternal cell contamination of the sample
- The quality and expertise of the laboratory performing the analysis
Understanding Your FISH-Prenatal Aneuploidy Detection (5 Probes- Trisomy 13,18,21,X,Y) Results
Results from this test indicate the number of copies of each of the five targeted chromosomes found in the sample. A brief guide to interpreting signals is provided below. Always review your results with your doctor or a qualified genetic counsellor.
| Chromosome | Normal Signal Count | Abnormal Signal Count | Possible Indication |
|---|---|---|---|
| Chromosome 13 | 2 signals | 3 signals | Trisomy 13 (Patau syndrome) |
| Chromosome 18 | 2 signals | 3 signals | Trisomy 18 (Edwards syndrome) |
| Chromosome 21 | 2 signals | 3 signals | Trisomy 21 (Down syndrome) |
| Chromosome X | 2 signals (female) or 1 signal (male) | 1 signal in female | Monosomy X (Turner syndrome) |
| Chromosome Y | 0 signals (female) or 1 signal (male) | Abnormal pattern | Sex chromosome aneuploidy |
These ranges are general guidelines. Your doctor will interpret your results based on your specific clinical situation, gestational age, and other factors. Always consult a qualified healthcare professional for personalised medical advice.
Results During Special Conditions
Certain conditions may affect how results are interpreted. Your genetic counsellor will take these into account.
- Mosaicism: When a pregnancy contains a mixture of normal and chromosomally abnormal cells, low-level mosaicism may not be detected by this test.
- Confined placental mosaicism: In CVS samples, the placenta may occasionally show chromosomal changes not present in the foetus, complicating interpretation.
- Maternal cell contamination: Blood-stained samples may contain maternal cells, which can affect the accuracy of results. The American College of Medical Genetics advises that irreversible clinical decisions should not be based on FISH results alone.
How to Maintain General Wellness
For prenatal genetic testing, maintaining overall pregnancy health is the most relevant form of support. However, it is important to note that the genetic make-up cannot be altered. Consider the following general wellness steps.
- Attend all scheduled prenatal check-ups and follow your obstetrician's guidance throughout your pregnancy.
- Discuss all results with a genetic counsellor or maternal-foetal medicine specialist, who can explain findings in context and advise on any further steps.
- Consider complementary testing such as full karyotyping or chromosomal microarray for a more complete assessment of foetal chromosomes, as this test covers only five specific chromosomes.
Lupin Diagnostics FISH-Prenatal Aneuploidy Detection (5 Probes- Trisomy 13,18,21,X,Y) Price
The FISH-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.
| City | Approximate Price (₹) |
|---|---|
| BHOPAL | 10300 |
| CHENNAI | 10300 |
| HYDERABAD | 10300 |
| KOLKATA | 10300 |
| NAVI MUMBAI | 10300 |
| PUNE | 10300 |
Disclaimer: Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
You can book the FISH- prenatal aneuploidy detection test online booking through the following steps.
- 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.
- Receive your report via email or WhatsApp within the stipulated turnaround time.
Frequently Asked Questions
The FISH-prenatal aneuploidy detection test provides rapid results, typically within a few days, by examining only five specific chromosomes (13, 18, 21, X, and Y). Full karyotyping analyses all 46 chromosomes but requires cell culture and takes five to nine days. FISH is often performed first, with karyotyping used alongside it for a complete picture.
CVS and amniocentesis both carry a very small risk of miscarriage (less than 1%). The FISH analysis performed on the collected sample carries no risk in itself. Your doctor will discuss the risks and benefits of the procedure with you before you give consent.
CVS samples are typically collected between 11 and 13 weeks of gestation. Your obstetrician or maternal-foetal medicine specialist will advise on the best timing based on your individual circumstances and clinical findings.
A normal FISH-prenatal aneuploidy detection result means that no abnormalities were detected in the five targeted chromosomes. It does not rule out birth defects caused by other chromosomal abnormalities, structural changes, or genetic variants not covered by this test. Complementary testing may be recommended for a fuller assessment.
Studies have shown greater than 98% analytical sensitivity for detecting aneuploidy across the five targeted chromosomes, with concordance exceeding 99.5% in informative samples when compared with karyotype results. However, low-level mosaicism and other specific conditions may not always be detected.
The FISH-prenatal aneuploidy detection (5 probes- trisomy 13,18,21,X,Y) panel covers only five chromosomes and cannot identify structural chromosomal rearrangements or abnormalities in other chromosomes. Full karyotyping or chromosomal microarray testing is therefore recommended alongside FISH to provide a more complete assessment of the foetal genome.
An abnormal result will be explained in detail by your doctor or genetic counsellor. They will typically recommend confirmatory testing, such as full karyotyping or chromosomal microarray, before any clinical decisions are made. Genetic counselling is available to help you understand the findings and consider the next steps.
FISH-Prenatal Aneuploidy Detection (5 Probes- Trisomy 13,18,21,X,Y)
