Prenatal chromosomal microarray analysis | CMA
| Test Details | Affymetrix CytoScan HD assay with genomic DNA extraction to detect small gains and losses across the entire genome. A genomic imbalance is ALWAYS REPORTED when deletions are greater than 200 kb and duplications are greater than 500 kb, unless they represent a region clearly associated with benign copy number polymorphism in multiple independent studies. Regions of LCSH are reported when they are greater than 10 Mb. Deletions smaller than 200 kb and duplications smaller than 500 kb are NOT REPORTED, unless they involve regions of the genome with clear clinical significance. Chromosome analysis will detect large balanced rearrangements. |
| Methodology | Chromosomal microarray analysis |
| Performed | Monday – Friday |
| Turnaround | 21 – 28 days |
| Specimen Requirements | Amniotic fluid (AF), chorionic villi sampling (CVS), percutaneous umbilical blood sampling (PUBS) |
| Sample Collection | AF: Discard first 2mL of amniotic fluid. Collect 15-25mL in a sterile syringe. Use sterile technique to transfer to 15mL sterile screw-top plastic conical tubes for transport. Do not centrifuge. CVS: Collect 15-40mg of budding villi in 50mL screw-top plastic conical tubes in sterile transport media (provided by cytogenetics lab). Do not centrifuge. PUBS: Collect 1-3mL in sterile, 15mL sodium heparin (green-top) Vacutainer tube. Collect under ultrasound guidance. Invert tube immediately upon completion of blood collection to prevent formation of clots. |
| Storage/Transport Conditions | Room temperature |
| Unacceptable Conditions | Will not be accepted after three days |
| Special Instructions | Refrigerate if sample cannot be delivered within 24 hours; Uniquely identify twins/multiples |
| CPT Code(s) | 81229 x 1, 88235 x 1, 88291 x 1, 88280 x 1, 88261 x 1 |