PRENATAL ANEUPLOIDY SCREEN BY FISH

Mnemonic

MISC

Synonym

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

Includes

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

Guidelines

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

Collect

Amniotic Fluid, obtained using sterile technique

Handling

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 three 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. Bloody amniotic fluid samples are not appropriate for FISH testing due to the possiblity of maternal cell contamination. 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. This should be noted on the tube. Keep specimen at ambient temperature and transport within 24 hours. Maintain sterility, do not split specimen or open tubes.

Transport

Room temperature within 24 hours of collection

Stability

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

Testing Information

Note

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.

Performed

Mon - Fri

Method

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

Referral Lab

Legacy Laboratory Services

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.

Last Updated: Thursday, January 5, 2017 03:42:25 AM