Prenatal Chromosomal Microarray Analysis (CMA) with Abbreviated Chromosome Analysis — Amniotic Fluid and Chorionic Villus Sampling

CPT Code(s):  81229, 88235, 88261, 81265

Service Code (IU Health): 53024030, 53101267, 53100566, 53025615

Ordering Recommendation: Genetic imbalances such as chromosomal deletions and duplications are known to be a significant cause of intellectual disability, birth defects, developmental disorders, and pregnancy loss. Traditional prenatal G-banded chromosome testing yields low resolution structural and numerical analysis of the chromosomes, while prenatal Chromosomal Microarray (CMA) provides high-definition copy number analysis. An abbreviated chromosome analysis (5 cells) will accompany the CMA report. Companion fluorescence in-situ hybridization (FISH) testing for prenatal aneuploidy screening (13, 18, 21, X, Y) may also be performed. No additional specimen is required.

Synonyms: CMA, Chromosomal Microarray, CGH, SNP, Microarray, Karyotype, G-bands, CVS, prenatal diagnosis, prenatal chromosomes.

Methodology: Cytogenomic SNP microarray. Tissue culture, microscopic analysis of G-banded chromosomes. If ordered, fluorescence in-situ hybridization (FISH) of interphase cells.

Performed: Monday through Friday

Reported: 7-10 days

Collect:

Amniotic Fluid:

• 20-25 ml amniotic fluid at 16 weeks of gestation or greater (30 ml fluid if additional studies are ordered).
• Discard first 2 ml to avoid maternal cell contamination. Transfer the remaining specimen to sterile 15 ml conical centrifuge tubes in 3-4 sterile aliquots, labeled 1st, 2nd, etc., and transport to the laboratory within 24 hours.
  • If the DNA yield from direct fluid is not adequate or the submitted sample is too small or suboptimal, analysis will be performed on cultured cells, which may require additional time for cell growth. Suboptimal specimens likely to cause longer turnaround times include bloody samples (fluid or cell pellet), low volume samples, gestational age < 16 weeks. In sterile, screw-top container filled with sterile transport medium (provided upon request).

CVS:

• 20-30 mg branched, clean fetal villi (50 mg if FISH/Chromosome testing also requested).
• Place in CVS transport media and transfer at room temperature to the laboratory within 24 hours.
  • If the DNA yield on uncultured cells is not adequate or the submitted sample is too small or suboptimal, analysis will be performed on cultured cells, which may require additional time for cell growth.

Parental Samples:

• 3 ml whole blood in lavender top (EDTA) tube OR one buccal swab (if needed, please call laboratory).
  • Please note: MATERNAL samples are REQUIRED to accompany the fetal sample. It is also recommended to send a paternal blood sample to determine the parental inheritance of CMA findings of uncertain clinical significance.
• Maternal cell contamination (MCC) studies will be performed in all cases.
  • When interpretation requires parental studies, these will be performed automatically to help clarify the significance of the fetal results.

Specimen Volume:

Amniotic Fluid: 20-25 ml amniotic fluid at 16 weeks of gestation or greater (30 ml fluid if additional studies are ordered).

CVS: 20-30 mg branched, clean fetal villi (50 mg if FISH/Chromosome testing also requested).

Parental Samples: 3 ml whole blood in lavender top (EDTA) tube OR one buccal swab (if needed, please call laboratory).

Storage/Transport: All specimens should be received with 24 hours. Keep amniotic fluid and CVS specimens refrigerated until transport. Parental bloods should remain at room temperature.

Unacceptable Conditions: Frozen. Formalin-fixed.

Stability: Ambient: 24 hours; Refrigerated: 48 hours; Frozen: Unacceptable