FISH Study: Chromosome Identification (for Constitutional Congenital Studies)

CPT Code(s):

  • 88271
  • 88273
  • 88291


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)


Monday - Saturday


10 - 21 days


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.).

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.

Collection Procedure:


Reference Values:

By report; interpretive

Interpretation Data:



UFHPL Test #: 30070

Reported Notes: