FISH Study: Chromosome Identification (for Constitutional Congenital Studies)

Additional Information:

UFHPL Test #: 30070

CPT Code(s):

  • 88271
  • 88273
  • 88291

Collection Procedure:


Specimen Requirements:

  • Peripheral Blood: Peripheral blood must be collected aseptically in sodium heparin tubes (usually green-top tubes) and immediately rotated thoroughly to prevent clotting. For infants, obtain approximately 2 cc and for children and adults obtain 5 - 7 cc.
  • Skin Biopsy or Other Tissues: In an aseptic manner, obtain approximately 2 mm x 2 mm, which is deep enough to ensure that the dermal layer is included. Deposit the specimen in a sterile container containing tissue culture medium with antibiotics (RPMI), which has been brought to room temperature prior to collection.* Alternate solid tissue samples include autopsy specimens (i.e., lung, cartilage, etc.).

Note: A separate blood sample is required if a concurrent CGH microarray study is desired. Do not freeze or fix samples in any manner contrary to the maintenance of cell viability. Maintain sample sterility; keep all specimens at room temperature; and deliver samples to the laboratory within 24 - 48 hours. Ship specimens at room temperature for overnight delivery.

* Cell viability of specimens requiring cell culture may be compromised in specimens more than 48 hours old upon receipt. Refrigeration at 2° - 8° C may assist when a delay is not preventable. Do not freeze or place specimens directly on ice.


This test is used to further characterize chromosome abnormalities, as previously identified by conventional karyotyping techniques (i.e., marker chromosome identification, derivative chromosome content, breakpoint analysis, etc.).


Metaphase fluorescence in-situ hybridization (FISH) analysis for characterization of de novo chromosomal findings; requires concurrent classic cytogenetic analysis; not for standalone use (prior chromosome study required)


10 - 21 days

Reference Values:

By report; interpretive


Monday - Saturday

Interpretation Data: