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Prenatal Aneuploidy Screen by FISH


FISH testing for Anueploidy - AneuVysion® - Prenatal FISH - Fluorescence In Situ Hybridization - Cytogenetics


Classical chromosome analysis; AF-AFP testing for gestational ages 14.0-22.9 weeks; Prenatal FISH probes for X, Y, 13, 18, and 21.


This is a FISH test used to detect aneuploidy of chromosomes X, Y, 13, 18, and 21, and is offered in conjunction with routine cytogenetic analysis. It is not intended to be a stand-alone test. The American College of Medical Genetics recommends that irreversible therapeutic action should not be taken on the basis of FISH results alone.

Specimen Collection Requirements


Amniotic Fluid, obtained using sterile technique


This is not a stand-alone test, the volume must be sufficient to include classical chromosome analysis. The first 1.0-2.0 mL should be expressed into a separate tube to clear the specimen of possible maternal cells. Distribute the rest of the specimen between 3 screw-top sterile polystyrene or polypropylene tubes. For cytogenetics testing, all drawn amniotic fluid should be sent, properly labeled, to the Cytogenetics laboratory. Do not refrigerate, freeze, or expose to extreme temperatures. Keep specimen at ambient temperature and transport within 24 hours. Maintain sterility do not split specimen or open tube.

Bloody amniotic fluid samples are not appropriate for FISH testing due to the possibility of maternal cell contamination. However, to insure the completion of the classical cytogenetics testing, if gross blood is present, add 0.25 mL of sodium heparin (1,000 units/mL) aseptically to each tube immediately after the tap. Addition of heparin should be noted on the tube.


Room temperature within 24 hours of collection

Rejection Criteria

Rejection is only at the discretion of the Cytogenetics Laboratory.


Ambient: 24 hours; Refrigerated: Suboptimal, call Cytogenetics at (503) 413-4613

Testing Information


Clinical information including the indication for study must accompany the specimen. This includes the gestational age, ultrasound findings, prenatal screening results, previous reproductive history and any known family history of birth defects. Requisitions for cytogenetics studies are available upon request.


Mon - Fri


FISH: 24-71 hours Cliassical Cytogenetics: 8-12 days


Fluorescent In Situ Hybridization (FISH) is performed on fetal cells obtained from amniotic fluid. An FDA approved assay called AneuVysion is used.

Reference Values

Reference Values

FISH testing will be reported as a preliminary report. The final report will also include the results and interpretation of the classical cytogenetic analysis. A computer generated karyotype is also provided with each study.
Normal range:
46,XX, apparently normal female
46,XY, apparently normal male
If Genetic Counseling is needed, call (503) 413-5214.


Call Client Services for assitance with specimen transportation or to obtain supplies.  For questions regarding the report, please call (503) 413-4613.

Last Updated: Wednesday, December 4, 2019 08:14:28 PM

Client Services: 503-413-1234