Fluorescence in situ Hybridization (FISH), Paraffin Block

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Test Details


  • Cytogenetics Fluorescence in situ Hybridization on Paraffin-embedded Tissue


For specific FISH probe analysis of tissue specimens


Samples in formaldehyde greater than 12 hours may reduce hybridization efficiency.

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA). The FDA has determined that such clearance or approval is not necessary.


Fluorescence in situ hybridization (FISH) from formalin-fixed tissue-embedded paraffin (4-micron to 5-micron sections); H&E for pathology review.

Specimen Requirements


Formalin/bone marrow-fixed (not decalcified); paraffin-embedded tissue or six 4-micron to 5-micron thick section slides


One paraffin block or six 4-micron to 5-micron thick section slides

Minimum Volume

Partial paraffin block to make several slides/probe


Paraffin block transport pouch


Specimen should be fixed in 10% neutral-buffered formalin or formaldehyde.

Storage Instructions

Maintain specimen at room temperature.

Causes for Rejection

Improperly embedded prep; poor fixation <6 hours and >72 hours; decalcified bone or bone core; broken or dirty slides; absence of tumor or quantity not sufficient for analysis

Clinical Information

Special Instructions

This test number is used for tracking FISH paraffin samples to the testing facility. Billing will occur after testing is completed.

Pertinent medical findings and probe desired must accompany request for FISH. If prior chromosome analysis has been performed, include a copy of the report. Please direct questions to genetics customer service at 800-345-4363.

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