Aneuploidy Detection in Peripheral Blood or Cord Blood Specimens — FISH Analysis

CPT Code(s): 88230, 88275 (x per analysis), 88271 (x per probe)

Service Code (IU Health): 53100293, 53100707, 53100640

Ordering Recommendation: FISH on peripheral or cord blood is useful for the detection of aneuploidy for chromosomes 13, 18, 21, X and Y. Most often this analysis will involve rapid testing of newborns to confirm suspected aneuploidy, based on either a clinical suspicion or an abnormal prenatal test result. A concurrent G-banded chromosome study is suggested. No additional specimen required.

Synonyms: FISH, aneuploidy, trisomy, monosomy

Methodology: Fluorescence in situ hybridization (FISH) analysis

Performed: Monday-Friday

Reported: Within 24-72 hours depending on time received in the laboratory and overlap with weekends and holidays. Final reports on most cases released within 24 hours if received in the laboratory by 2:00 p.m. EST Monday-Thursday.

Collect: Non-diluted blood in sodium heparin (dark green top) tube.

Specimen Volume: Preferred: 2 mL blood; 1 mL (minimum)

Storage/Transport: Room temperature. Do not freeze or expose to extreme temperatures.

Unacceptable Conditions: Frozen.

Stability: Ambient: 24 hours; Refrigerated: 48 hours

Characteristics: When the percent of cells with an abnormality exceeds the normal reference range for any given probe, it is considered an abnormal result. Absence of an abnormal result does not rule out the possibility of an aneuploidy. A report detailing interpretation of results will be provided.

Limitations: The probes in this FISH assay detect only their intended targets. Chromosomal alterations present outside the regions targeted by the probes will not be detected. This analysis does not eliminate the possibility of low frequency mosaicism or small structural abnormalities. Due to the limitations of interphase FISH, results are suggested to be correlated with a concurrent G-banded karyotype analysis.