Fluorescence in situ Hybridization (FISH), Prenatal Aneuploid Evaluation, Chorionic Villus Sampling With Reflex to Microarray or Chromosome Analysis
Also known as: aCGH, CGH, Chromosome Analysis, CMA, CVS FISH
Use
FISH allows for rapid identification of common prenatal aneuploidy (specific for X, Y, 13, 18, 21). An abnormal result reflexes to karyotyping (G-band chromosome analysis). A normal FISH result reflexes to the SNP assay, which will detect chromosomal imbalances that could be associated with developmental delay/congenital anomalies. It provides detection of possible uniparental disomy of any chromosome, the percent and location of homozygosity, including the degree of identity by descent.
Special Instructions
Pertinent medical history and test request form must accompany each request for chromosome analysis. If an abnormal FISH result is obtained, it will reflex to chromosome karyotyping, and if the FISH result is normal, it will reflex to microarray testing. A completed Informed Consent and Prenatal Chromosome SNP Microarray Questionnaire form should accompany specimens. For assistance or to request forms, call 800-345-4363. Concurrent maternal contamination studies (MCC) are recommended.
Limitations
The test detects only the most common prenatal aneusomies and requires cytogenetic confirmation for all abnormal FISH results. It will not detect balanced rearrangements or low-level mosaicism. Extensive maternal cell contamination can limit the assay's sensitivity, and the SNP assay will not detect balanced rearrangements, low-level mosaicism (<10%), marker chromosomes containing only heterochromatin, or tetraploidy.
Methodology
Chromosomal / Cytogenetics (FISH)
Biomarkers
LOINC Codes
- 64089-6
- 64086-2
- 57318-8
- 62365-2
- 31208-2
- 72486-4
Result Turnaround Time
10-13 days
Related Documents
For more information, please review the documents below
Specimen
Tissue (Fresh)
Volume
20-30 mg
Minimum Volume
20 mg
Container
CVS transport tube (sterile specimen container with transport medium)
Collection Instructions
Specimen is collected in a syringe (transabdominal) or catheter (transcervical) and transferred by flushing with the media from the sterile container back into it. After collection, wash with sterile saline solution (NaCl 0.95%) containing sodium heparin (two to three drops of sodium heparin in 10 mL of saline). Transfer the specimen into the CVS transport tube using a sterile Pasteur pipette or fine needle forceps. Ensure transport tubes are filled completely with media. For multiple pregnancies, label and place samples in separate containers with separate request forms.
Storage Instructions
Maintain specimen at room temperature and transport to the laboratory immediately. Refrigerate if sterility is questioned or if not shipped within 24 hours. Do not freeze.
Causes for Rejection
No villi submitted or low volume in specimen; improper labeling; frozen or contaminated villi; specimen placed in fixative; wrong specimen or maternal decidua received
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