FISH - Opposite Sex BMT (XX / XY) Test
Short Name: FISH BMT XX/XY
Also known as: FISH BMT Chimerism Test, XX XY FISH Analysis, Bone Marrow Transplant Engraftment FISH, FISH Sex Chromosome Chimerism Test, Opposite Sex BMT FISH Test
FISH - Opposite Sex BMT (XX / XY) Test test available at DNA Labs India for ₹6,000. Uses FISH (Fluorescence In Situ Hybridization) on Whole Blood or Bone Marrow samples. Results in Sample accepted daily by 4:00 PM. Report available in 4 working 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 the FISH Opposite Sex BMT (XX/XY) test is to determine the percentage of donor (XX) and recipient (XY) cells, or vice versa, in a patient's blood or bone marrow following an allogeneic bone marrow transplant between opposite-sex individuals. This quantification provides a direct indication of the success of engraftment in conditions such as Chronic Myeloid Leukemia (CML) and Aplastic Anemia. By tracking changes in chimerism over time, clinicians can detect early signs of graft rejection, graft-versus-host disease, or disease relapse, allowing for prompt therapeutic adjustments.
- Test Code
- 601
- CPT Code
- 88271
- ICD Code
- Z94.84
- Price
- ₹6,000
- Sample Type
- Whole Blood or Bone Marrow
- Result Time
- Sample accepted daily by 4:00 PM. Report available in 4 working days.
- Fasting Required
- No
- Method
- FISH (Fluorescence In Situ Hybridization)
Sample Collection
No special preparation such as fasting is required. Ensure the duly filled Chromosome & FISH Analysis Requisition Form (Form 17) is completed and accompanies the sample. Inform the collection centre of any recent blood transfusions, as these may affect chimerism results.
Method: Venipuncture (blood) or Bone Marrow Aspiration
Laboratory Analysis
A qualified phlebotomist or haematologist will collect 5 mL (minimum 3 mL) of whole blood via venipuncture or 4 mL (minimum 2 mL) of bone marrow via aspiration. Both sample types must be collected in Green Top (Sodium Heparin) tubes. The sample must be shipped at 18–22°C. DO NOT FREEZE.
Report Delivery
No special post-collection care is required. Apply gentle pressure to the puncture site with a cotton ball or gauze for 3–5 minutes to prevent bruising. Mild soreness at the collection site is normal and resolves within a day.
Timeline: Sample accepted daily by 4:00 PM. Report available in 4 working days.
Patient Instructions
About This Test
Who Should Get This Test
The primary purpose of the FISH Opposite Sex BMT (XX/XY) test is to determine the percentage of donor (XX) and recipient (XY) cells, or vice versa, in a patient's blood or bone marrow following an allogeneic bone marrow transplant between opposite-sex individuals. This quantification provides a direct indication of the success of engraftment in conditions such as Chronic Myeloid Leukemia (CML) and Aplastic Anemia. By tracking changes in chimerism over time, clinicians can detect early signs of graft rejection, graft-versus-host disease, or disease relapse, allowing for prompt therapeutic adjustments.
How to Prepare
- Collect sample in Green Top (Sodium Heparin) tubes only
- Blood volume: 5 mL (minimum 3 mL); Bone marrow volume: 4 mL (minimum 2 mL)
- Ship at 18–22°C. DO NOT FREEZE the sample
- Duly filled Chromosome & FISH Analysis Requisition Form (Form 17) is mandatory
- Label the tube clearly with patient name, date of birth, and sample date
- Deliver the sample to the laboratory by 4:00 PM daily for same-day processing
- Avoid collecting the sample from the same arm used for IV infusions
Doctor's Notes
Reviewed by Dr SHAILAJA RAGHUNATH MURDESHWAR — MBBS, MD (General Medicine) · Reg. No. 8052
"As a haematologist managing bone marrow transplant patients, I rely on the FISH Opposite Sex BMT (XX/XY) test to objectively quantify donor versus recipient chimerism. When a male recipient receives marrow from a female donor or vice versa, sex chromosome FISH provides a rapid, reliable and visual method to track engraftment. A declining proportion of donor cells can signal impending graft rejection or disease relapse, enabling timely clinical intervention. This test is especially valuable in monitoring patients with CML and aplastic anemia in the post-transplant period."
Last medically reviewed: September 7, 2026
Test Parameters & Specifications
Sample Stability
- Sample collected in an incorrect tube (non-heparin anticoagulant)
- Clotted sample
- Severely haemolysed sample
- Insufficient sample volume (less than 3 mL blood or 2 mL bone marrow)
- Unlabelled or mislabelled sample
- Missing or incomplete Chromosome & FISH Analysis Requisition Form (Form 17)
- Sample received frozen or at temperatures outside 18–22°C
- Sample received more than 48 hours after collection
Understanding Your Results
Complete Chimerism (≥95% donor cells)
Indicates successful engraftment. The transplanted bone marrow has effectively replaced the recipient's haematopoietic system. Patient is responding well to the transplant.
Action: Continue routine post-transplant monitoring as advised by your transplant team.
Mixed Chimerism (5–94% donor cells)
Suggests coexistence of both donor and recipient haematopoietic cells. This may indicate incomplete engraftment, impending graft rejection, or early disease relapse. The clinical significance depends on the trend over serial measurements.
Action: Consult your haematologist immediately. Closer monitoring and possible therapeutic intervention such as donor lymphocyte infusion (DLI) or immunosuppression adjustment may be required.
Graft Rejection (<5% donor cells)
Indicates that the recipient's immune system has rejected the transplanted marrow. The patient's own haematopoietic cells have reconstituted, and the transplant has largely failed.
Action: Urgent consultation with the transplant specialist is necessary. Re-transplantation or alternative treatment strategies may need to be considered.
Consult your haematologist or bone marrow transplant specialist if your FISH BMT test shows mixed chimerism with a declining donor cell percentage, or if you experience symptoms such as persistent fatigue, recurrent infections, unexplained fever, easy bruising, abnormal bleeding, or significant weight loss following a bone marrow transplant. A rising trend of recipient cells on serial testing warrants immediate clinical evaluation to rule out graft rejection or disease relapse.
Limitations
- ⚠This test is applicable only when the bone marrow transplant involves a donor and recipient of opposite sexes
- ⚠FISH analysis is performed on interphase nuclei; very low-level mixed chimerism (<2%) may not be reliably detected
- ⚠The test does not distinguish between different cell lineages (e.g., myeloid vs lymphoid chimerism)
- ⚠Results should always be correlated with clinical findings, complete blood counts, and other relevant investigations
- ⚠Polymorphic variations in sex chromosomes may rarely affect probe hybridization efficiency
Risks & Considerations
- ●Minor bruising or discomfort at the blood draw or bone marrow aspiration site
- ●Slight risk of infection at the needle insertion site (standard aseptic precautions are followed)
- ●Bone marrow aspiration may cause temporary localized pain, which typically resolves within 24–48 hours
Interfering Factors
- ●Sample contamination or mix-up with another patient's sample
- ●Excessive hemolysis in the blood sample may affect cell viability
- ●Clotted sample may reduce the number of analysable interphase nuclei
- ●Use of an incorrect anticoagulant (non-heparin tubes) can compromise FISH signal quality
- ●Prolonged storage beyond 48 hours at room temperature may degrade nuclei integrity
- ●Recent transfusion of blood products may temporarily alter chimerism proportions
Compare With Similar Tests
| Test | FISH - Opposite Sex BMT (XX / XY) Test | |||||
|---|---|---|---|---|---|---|
| Comparison | FISH - Opposite Sex BMT (XX / XY) Test |
Frequently Asked Questions
What is the FISH Opposite Sex BMT (XX/XY) test?
Why is this test performed after a bone marrow transplant?
What sample is required for the FISH BMT test?
Is fasting required before this test?
How long does it take to get the results?
What does complete chimerism mean?
What does mixed chimerism indicate?
What are the signs of graft rejection after a bone marrow transplant?
Can this test be used for same-sex bone marrow transplants?
What is the cost of the FISH Opposite Sex BMT (XX/XY) test at DNA Labs India?
Does DNA Labs India offer home sample collection for this test?
How should I prepare for the FISH BMT test?
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