Test Details
Methodology
In situ cell culturing of amniocytes to investigate numerical and/or structural chromosome abnormalities. A normal chromosome analysis will reflex to SNP microarray analysis using the Cytoscan® HD platform, which uses more than 743,000 SNP probes and 1,953,000 NPCN probes with a median spacing of 0.88 kb.
Result Turnaround Time
7 - 11 days
Use
The chromosome analysis determines fetal karyotype. A normal chromosome analysis will reflex to a high-resolution SNP microarray analysis targeting 2.695 million copy-number and allele-specific genome sites. The SNP assay will detect chromosomal imbalances that could be associated with developmental delay/congenital anomalies. It provides possible detection of uniparental disomy of any chromosome, the percent and location of homozygosity, including the degree of identity by descent.
Special Instructions
Pertinent medical findings must accompany request.
If prior NIPT studies have been performed, include copy of the report.
Specimen Requirements
Limitations
Although the overall culture success rate is reported as >99%, culture failure can result. Reasons include (but are not limited to) lack of amniocytes in the fluid and contamination of the fluid with bacteria or yeast. For the SNP assay, it does not detect balanced rearrangements, low-level mosaicism (<10%), marker chromosomes that only contain heterochromatin or tetraploidy.
This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration.
Custom Additional Information
Additional biochemical or molecular tests may be performed on the cultured amniocytes.
Fetal loss rate is considered to be 0.5% at 14 to 18 week sampling and 2% to 3% at 10 to 13 weeks.1 Chorionic villus sampling (CVS) may be safer than early amniocentesis for early prenatal diagnosis of cytogenetic abnormalities.2,3
The risk of miscarriage with CVS is 1% to 1.5%, but the risk of maternal infection appears to be higher with CVS than with amniocentesis.4 Cytogenetic analyses using such samples allow for early gestational testing based on a 10- to 11-week placental biopsy and a five-day cytogenetic study. Most failures are due to an inappropriate biopsy containing only maternal decidua. Chromosomal aberrations were found in 4.6% of fetuses in women older than 38 to 40 years. Trisomy 21 was the most common abnormality (62%). Klinefelter syndrome (11%), Edwards syndrome, and trisomy 18 (11%) were the next most frequent in the cases of advanced maternal age.
Prenatal diagnosis is possible for more than 1000 inherited diseases. Most are inherited in an autosomal recessive manner. Antenatal diagnosis using gene probes has become available for cystic fibrosis, muscular dystrophy, sickle cell anemia, hemophilia, and many other genetic abnormalities. This can be done from either cultured amniotic fluid cells or chorionic villus sampling.5
Specimen
Amniotic fluid, fetal urine, or cystic hygroma fluid
Volume
20 to 30 mL (15 to 20 mL for early amniocentesis)
Minimum Volume
5 mL (Minimum volume may delay results due to fewer cells available for culture.)
Container
Sterile plastic conical tube
Storage Instructions
Maintain specimen at room temperature. Do not refrigerate or freeze.
Causes for Rejection
Specimen found not to be amniotic fluid; gross contamination with blood cells; frozen specimen; containers with rubber stoppers (rubber is toxic to amniocytes)
Collection Instructions
Discard first 2 mL of fluid aspirated to avoid maternal cell contamination. Specimen is collected in a 20-mL sterile syringe and transferred aseptically to sterile tubes to be transported to LabCorp. Test request form is completed and accompanies specimen and miscellaneous slip to the laboratory.
Footnotes
LOINC® Map
Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
---|---|---|---|---|---|---|
052104 | Chromosome Amnio RFX CMA | 052138 | Cells Counted | 64095-3 | ||
052104 | Chromosome Amnio RFX CMA | 052139 | Colonies | 64096-1 | ||
052104 | Chromosome Amnio RFX CMA | 052140 | Cells Analyzed | 64092-0 | ||
052104 | Chromosome Amnio RFX CMA | 052141 | Cells Karyotyped | 64091-2 | ||
052104 | Chromosome Amnio RFX CMA | 052143 | GTG Band Resolution Achieved | 64093-8 | ||
052104 | Chromosome Amnio RFX CMA | 052144 | Cytogenetic Diagnosis | 62356-1 | ||
052104 | Chromosome Amnio RFX CMA | 052016 | Cytogenetic Interpretation | 64094-6 | ||
052104 | Chromosome Amnio RFX CMA | 052146 | Specimen Type | 48002-0 | ||
052104 | Chromosome Amnio RFX CMA | 052017 | Director Review: | 48672-0 | ||
052104 | Chromosome Amnio RFX CMA | 052320 | Reflex | N/A | ||
052104 | Chromosome Amnio RFX CMA | 512123 | 11502-2 | |||
Order Code | 052104 | |||||
Order Code Name | Chromosome Amnio RFX CMA | |||||
Order Loinc | ||||||
Result Code | 052138 | |||||
Result Code Name | Cells Counted | |||||
UofM | ||||||
Result LOINC | 64095-3 | |||||
Order Code | 052104 | |||||
Order Code Name | Chromosome Amnio RFX CMA | |||||
Order Loinc | ||||||
Result Code | 052139 | |||||
Result Code Name | Colonies | |||||
UofM | ||||||
Result LOINC | 64096-1 | |||||
Order Code | 052104 | |||||
Order Code Name | Chromosome Amnio RFX CMA | |||||
Order Loinc | ||||||
Result Code | 052140 | |||||
Result Code Name | Cells Analyzed | |||||
UofM | ||||||
Result LOINC | 64092-0 | |||||
Order Code | 052104 | |||||
Order Code Name | Chromosome Amnio RFX CMA | |||||
Order Loinc | ||||||
Result Code | 052141 | |||||
Result Code Name | Cells Karyotyped | |||||
UofM | ||||||
Result LOINC | 64091-2 | |||||
Order Code | 052104 | |||||
Order Code Name | Chromosome Amnio RFX CMA | |||||
Order Loinc | ||||||
Result Code | 052143 | |||||
Result Code Name | GTG Band Resolution Achieved | |||||
UofM | ||||||
Result LOINC | 64093-8 | |||||
Order Code | 052104 | |||||
Order Code Name | Chromosome Amnio RFX CMA | |||||
Order Loinc | ||||||
Result Code | 052144 | |||||
Result Code Name | Cytogenetic Diagnosis | |||||
UofM | ||||||
Result LOINC | 62356-1 | |||||
Order Code | 052104 | |||||
Order Code Name | Chromosome Amnio RFX CMA | |||||
Order Loinc | ||||||
Result Code | 052016 | |||||
Result Code Name | Cytogenetic Interpretation | |||||
UofM | ||||||
Result LOINC | 64094-6 | |||||
Order Code | 052104 | |||||
Order Code Name | Chromosome Amnio RFX CMA | |||||
Order Loinc | ||||||
Result Code | 052146 | |||||
Result Code Name | Specimen Type | |||||
UofM | ||||||
Result LOINC | 48002-0 | |||||
Order Code | 052104 | |||||
Order Code Name | Chromosome Amnio RFX CMA | |||||
Order Loinc | ||||||
Result Code | 052017 | |||||
Result Code Name | Director Review: | |||||
UofM | ||||||
Result LOINC | 48672-0 | |||||
Order Code | 052104 | |||||
Order Code Name | Chromosome Amnio RFX CMA | |||||
Order Loinc | ||||||
Result Code | 052320 | |||||
Result Code Name | Reflex | |||||
UofM | ||||||
Result LOINC | N/A | |||||
Order Code | 052104 | |||||
Order Code Name | Chromosome Amnio RFX CMA | |||||
Order Loinc | ||||||
Result Code | 512123 | |||||
Result Code Name | ||||||
UofM | ||||||
Result LOINC | 11502-2 |
Order Code | Order Name | Result Code | Result Name | UofM | Result LOINC | |
---|---|---|---|---|---|---|
Reflex 1 | 510098 | Chromosome Microarray | 510216 | Chromosome Microarray | N/A | |
Reflex 1 | ||||||
Order Code | 510098 | |||||
Order Name | Chromosome Microarray | |||||
Result Code | 510216 | |||||
Result Name | Chromosome Microarray | |||||
UofM | ||||||
Result LOINC | N/A |
Order Code | Order Name | Result Code | Result Name | UofM | Result LOINC | |
---|---|---|---|---|---|---|
Reflex 1 | 510098 | Chromosome Microarray | 510043 | Specimen Type | 31208-2 | |
Reflex 1 | ||||||
Order Code | 510098 | |||||
Order Name | Chromosome Microarray | |||||
Result Code | 510043 | |||||
Result Name | Specimen Type | |||||
UofM | ||||||
Result LOINC | 31208-2 |
Order Code | Order Name | Result Code | Result Name | UofM | Result LOINC | |
---|---|---|---|---|---|---|
Reflex 1 | 510098 | Chromosome Microarray | 510044 | # of Genotyping Targets | N/A | |
Reflex 1 | ||||||
Order Code | 510098 | |||||
Order Name | Chromosome Microarray | |||||
Result Code | 510044 | |||||
Result Name | # of Genotyping Targets | |||||
UofM | ||||||
Result LOINC | N/A |
Order Code | Order Name | Result Code | Result Name | UofM | Result LOINC | |
---|---|---|---|---|---|---|
Reflex 1 | 510098 | Chromosome Microarray | 510045 | Array Type | N/A | |
Reflex 1 | ||||||
Order Code | 510098 | |||||
Order Name | Chromosome Microarray | |||||
Result Code | 510045 | |||||
Result Name | Array Type | |||||
UofM | ||||||
Result LOINC | N/A |
Order Code | Order Name | Result Code | Result Name | UofM | Result LOINC | |
---|---|---|---|---|---|---|
Reflex 1 | 510098 | Chromosome Microarray | 510048 | Diagnosis | 48000-4 | |
Reflex 1 | ||||||
Order Code | 510098 | |||||
Order Name | Chromosome Microarray | |||||
Result Code | 510048 | |||||
Result Name | Diagnosis | |||||
UofM | ||||||
Result LOINC | 48000-4 |
Order Code | Order Name | Result Code | Result Name | UofM | Result LOINC | |
---|---|---|---|---|---|---|
Reflex 1 | 510098 | Chromosome Microarray | 510049 | Interpretation | 50398-7 | |
Reflex 1 | ||||||
Order Code | 510098 | |||||
Order Name | Chromosome Microarray | |||||
Result Code | 510049 | |||||
Result Name | Interpretation | |||||
UofM | ||||||
Result LOINC | 50398-7 |
Order Code | Order Name | Result Code | Result Name | UofM | Result LOINC | |
---|---|---|---|---|---|---|
Reflex 1 | 510098 | Chromosome Microarray | 510061 | Director Review | 48672-0 | |
Reflex 1 | ||||||
Order Code | 510098 | |||||
Order Name | Chromosome Microarray | |||||
Result Code | 510061 | |||||
Result Name | Director Review | |||||
UofM | ||||||
Result LOINC | 48672-0 |
Order Code | Order Name | Result Code | Result Name | UofM | Result LOINC | |
---|---|---|---|---|---|---|
Reflex 1 | 510098 | Chromosome Microarray | 512123 | 11502-2 | ||
Reflex 1 | ||||||
Order Code | 510098 | |||||
Order Name | Chromosome Microarray | |||||
Result Code | 512123 | |||||
Result Name | ||||||
UofM | ||||||
Result LOINC | 11502-2 |