FISH Study: Prenatal Chromosome Identification

Additional Information:

UFHPL Test #: 30265

CPT Code(s):

  • 88271
  • 88273
  • 88291

Collection Procedure:


Specimen Requirements:

  • Amniotic Fluid: Aseptically collect approximately 1 cc of per week of gestational age in two sterile 15 mL conical centrifuge tubes and sequentially label the tubes. The initial 1 - 2 cc should not be included for chromosome studies (but may be utilized for AFP testing).
  • Chorionic Villi: Collect 10 - 30 mg of utilizing aspiration medium containing sodium heparin.* After assessment of the appropriate amount and quality of villi, transfer to a sterile centrifuge tube with transportation medium.

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.

  • Unacceptable Conditions:
    • Frozen specimens
    • Specimens greater than 48 hours old*
  • Stability (collection to initiation of testing):
    • Ambient: 24 - 48 hours*
    • Frozen: Unacceptable

* 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.

Contact UF Health Pathology Laboratories prior to submission (approved by consultation).


This test is used further characterize chromosome abnormalities as previously identified by conventional G-banding techniques in prenatal studies (e.g., marker chromosome identification, derivative chromosome content, breakpoint analysis, etc.).


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


10 - 21 days

Reference Values:

By report; interpretive


Monday - Saturday

Interpretation Data: