FISH for Pre or Postnatal Diagnosis Chromosome 18, X Y Test
Short Name: FISH Chr 18, X, Y
Also known as: FISH for Chromosome 18, X, Y, Prenatal FISH Aneuploidy, Postnatal FISH Sex Chromosomes
FISH for Pre or Postnatal Diagnosis Chromosome 18, X Y Test test available at DNA Labs India for ₹7,000. Uses Fluorescence In Situ Hybridization (FISH) on Amniotic fluid, Chorionic villi, Peripheral blood, Bone marrow samples. Results in Preliminary results may be available within 48-72 hours, but the final report is issued in 10-12 days.. Free home collection in 300+ cities across India.
🩺 Medically Reviewed By
Dr SHAILAJA RAGHUNATH MURDESHWAR
Consultant Physician · Reg: 8052
Last reviewed: September 7, 2026
Overview
The primary purpose of this FISH test is to detect numerical abnormalities (aneuploidy) of chromosomes 18, X, and Y. It is used as an adjunct to traditional karyotyping to provide rapid results, often within 24-48 hours, although the full report is provided in 10-12 days. This test helps in diagnosing conditions like Trisomy 18, Turner syndrome, Klinefelter syndrome, and other sex chromosome aneuploidies, enabling timely medical intervention and genetic counseling.
- Test Code
- 6284
- CPT Code
- 88271, 88275
- ICD Code
- Z36.8, Q99.8
- Price
- ₹7,000
- Sample Type
- Amniotic fluid, Chorionic villi, Peripheral blood, Bone marrow
- Result Time
- Preliminary results may be available within 48-72 hours, but the final report is issued in 10-12 days.
- Fasting Required
- No
- Method
- Fluorescence In Situ Hybridization (FISH)
Sample Collection
No special preparation is required. For prenatal testing, the procedure (amniocentesis or CVS) will be performed by a qualified obstetrician. Inform your doctor about any medications or supplements you are taking.
Method: Venipuncture or Amniocentesis/CVS
Laboratory Analysis
For blood sample: A standard venipuncture will be performed. For prenatal samples: The procedure may cause mild discomfort; you will be monitored by the healthcare provider.
Report Delivery
For blood sample: No specific aftercare needed. For prenatal procedures: Rest for a short period and avoid strenuous activity for 24 hours. Contact your doctor if you experience fever, bleeding, or unusual pain.
Timeline: Preliminary results may be available within 48-72 hours, but the final report is issued in 10-12 days.
Patient Instructions
About This Test
Who Should Get This Test
The primary purpose of this FISH test is to detect numerical abnormalities (aneuploidy) of chromosomes 18, X, and Y. It is used as an adjunct to traditional karyotyping to provide rapid results, often within 24-48 hours, although the full report is provided in 10-12 days. This test helps in diagnosing conditions like Trisomy 18, Turner syndrome, Klinefelter syndrome, and other sex chromosome aneuploidies, enabling timely medical intervention and genetic counseling.
How to Prepare
- Peripheral blood: Collect in a sodium heparin tube, mix gently, and transport at room temperature within 48 hours.
- Amniotic fluid: Collect in sterile container, transport at room temperature, avoid freezing.
- Chorionic villi: Collect in sterile container with transport medium, keep at room temperature.
Doctor's Notes
Reviewed by Dr SHAILAJA RAGHUNATH MURDESHWAR — MBBS, MD (General Medicine) · Reg. No. 8052
"FISH testing is crucial for rapid aneuploidy detection, especially in high-risk pregnancies. Early diagnosis allows informed decision-making and appropriate management."
Last medically reviewed: September 7, 2026
Test Parameters & Specifications
Sample Stability
- Clotted blood sample
- Hemolyzed sample
- Insufficient sample volume
- Sample received after 48 hours at room temperature
- Frozen or refrigerated prenatal samples
Understanding Your Results
3 signals for chromosome 18
Indicates Edwards syndrome, associated with severe developmental delay and multiple congenital anomalies
1 signal for X, 0 for Y
Indicates monosomy X, associated with short stature, ovarian dysgenesis, and cardiac anomalies
2 signals for X, 1 for Y
Indicates extra X chromosome in males, associated with infertility, gynecomastia, and learning difficulties
3 signals for X, 0 for Y
Indicates extra X chromosome in females, often mild phenotype
1 signal for X, 2 for Y
Indicates extra Y chromosome in males, usually tall stature, normal fertility
Consult your doctor if you have any concerns about your pregnancy or your child's development. Genetic counseling is recommended for all patients undergoing this test to understand the implications of the results.
Limitations
- ⚠FISH only detects specific aneuploidies for the tested chromosomes; it does not detect structural abnormalities or other chromosomal imbalances
- ⚠Low-level mosaicism may not be detected
- ⚠Results should be confirmed by conventional karyotyping or chromosomal microarray
- ⚠Not a substitute for comprehensive genetic analysis
Risks & Considerations
- ●For prenatal procedures: small risk of miscarriage (0.1-0.3%)
- ●Bleeding or infection at the puncture site
- ●Maternal cell contamination leading to false results
- ●Emotional distress due to abnormal results
Interfering Factors
- ●Maternal cell contamination in prenatal samples
- ●Inadequate sample volume or poor DNA quality
- ●Recent blood transfusion (for postnatal blood samples)
- ●Mosaic low-level aneuploidy may be missed
- ●Technical issues with probe hybridization
Compare With Similar Tests
| Test | FISH for Pre or Postnatal Diagnosis Chromosome 18, X Y | Karyotyping | Chromosomal Microarray (CMA) | NIPT (Non-Invasive Prenatal Testing) |
|---|---|---|---|---|
| Comparison | FISH for Pre or Postnatal Diagnosis Chromosome 18, X Y |
Frequently Asked Questions
What is FISH for Chromosome 18, X, Y?
How is the FISH test performed?
What is the cost of the FISH test at DNA Labs India?
Is fasting required before the test?
How long does it take to get the results?
What is the difference between FISH and karyotyping?
Can this test be done during pregnancy?
What conditions can this test detect?
Is home sample collection available?
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₹7,371Reference Laboratory Services
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