Standard karyotype for amnio/chorionic villi1
Test #:
201
Turnaround Time:
8-14 days
Specimen Requirements:
Specimens should be shipped at room temperature in a leak-proof, rigid container with overnight delivery. To discuss minimum acceptable specimens for prenatal patients or for sample types not listed, please contact Allele Diagnostics.
- Amniotic fluid: 15-20 mL whole fluid
- Chorionic villus sampling (CVS): 5-10 mg tissue in sterile media or saline
- Cultured Cells: 2 x T-25 flasks (70% confluent)
CPT Codes:
88235 x1, 88267 x1 (CVS), 88269 x1 (Amniotic Fluid), 88280 x1, 88291 x1
Ordering Requirements:
Clinical Utility:
- Abnormal cell-free fetal DNA test.
- Abnormal fetal ultrasound findings consistent with a trisomy phenotype.2
- Abnormal maternal serum screen.
- Any patient undergoing invasive prenatal testing.
- Parental concern/anxiety.
- Patients with a known or suspected family history of a chromosome abnormality detectable by karyotype.
- Previous pregnancy with aneuploidy.
Test Description:
Chromosome analysis by karyotype.
Karyotype can identify numeric chromosomal abnormalities, large unbalanced and balanced structural abnormalities. Abnormalities larger than approximately 5-10 Mb can be visualized. Karyotype is useful in conjunction with microarray to identify balanced abnormalities, such as translocations and inversions, that microarray is not designed to detect. Standard blood karyotype study involves counting 20 cells, analyzing 5 cells, and karyotyping 3 cells. Additional cells are evaluated as indicated if mosaicism is suspected.
References:
- American College of Obstetricians and Gynecologists Committee on Genetics. Committee Opinion No. 581: The use of chromosomal microarray analysis in prenatal diagnosis. Obstet Gynecol, 122(6):1374-1377 (2013). PubMed: 24264715
- American College of Obstetricians and Gynecologists. Practice Bulletin No. 162 Summary: Prenatal Diagnostics Testing for Genetic Disorders. Obstet Gynecol, 127(5):976-978 (2016). PubMed: 27101119