InSight: Fluorescence in situ Hybridization (FISH), Prenatal Aneuploid Evaluation, Amniotic Fluid With Reflex to Microarray or Chromosome Analysis
Also known as: aCHG, CGH, Chromosome Analysis, Prenatal FISH, Amniotic Fluid, CMA, FISH, Prenatal
Use
Rapid identification of common prenatal aneuploidy (specific for X, Y, 13, 18, 21). If abnormal, reflex to banded chromosomes to obtain fetal karyotype. This test allows prenatal detection of chromosomal rearrangements, aneuploidy, or mosaicism. Such groups include women who:
Special Instructions
Pertinent medical findings should accompany the request for FISH. A completed Informed Consent and Prenatal Chromosome SNP Microarray Questionnaire should accompany specimens. Call 800-345-4363 to request the form. In the case of a reflex to microarray, concurrent maternal contamination studies are recommended.
Limitations
FISH detects only the most common aneuploidies found in the second trimester. Abnormal results will reflex to banded chromosome analysis. The overall culture success rate is reported as >99%, but culture failure can occur due to lack of amniocytes or contamination. FISH does not detect balanced rearrangements and may not detect low-level mosaicism. The SNP assay does not detect balanced rearrangements, low-level mosaicism (under 10%), marker chromosomes with only heterochromatin, or tetraploidy. Extensive maternal cell contamination can limit assay sensitivity.
Methodology
Chromosomal / Cytogenetics (FISH)
Biomarkers
LOINC Codes
- 64095-3
- 64092-0
- 57317-0
- 55192-9
- 31208-2
- 48672-0
Result Turnaround Time
10-13 days
Related Documents
For more information, please review the documents below
Specimen
Amniotic Fluid
Volume
25 mL or greater
Minimum Volume
25 mL
Container
Sterile plastic conical tube
Collection Instructions
Discard first 2 mL of fluid aspirated to avoid maternal cell contamination. Specimen is collected in a 20 mL sterile syringe and transferred aseptically to sterile tubes for transport.
Patient Preparation
The patient should preferably have had an ultrasound study to verify fetal life, detect multiple gestations, confirm gestational age, and localize the fetus/placenta.
Storage Instructions
Maintain specimen at room temperature.
Causes for Rejection
Specimen not amniotic fluid; gross contamination with blood cells; frozen specimen; container with rubber stopper; insufficient quantity for analysis.