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HelpTest ID: CHRAF Chromosome Analysis, Amniotic Fluid
Useful For
Prenatal diagnosis of chromosome abnormalities, including aneuploidy (ie, trisomy or monosomy) and balanced rearrangements
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| _ML15 | Metaphases, <15 | No, (Bill Only) | No |
| _M15 | Metaphases, 15 | No, (Bill Only) | No |
| _MG14 | Metaphases, >15 | No, (Bill Only) | No |
| _COL1 | Colonies, 1-5 | No, (Bill Only) | No |
| _COL6 | Colonies, 6+ | No, (Bill Only) | No |
| _KTG1 | Karyotypes, >1 | No, (Bill Only) | No |
| _STAC | Ag-Nor/CBL Stain | No, (Bill Only) | No |
Testing Algorithm
This test includes a charge for cell culture of fresh specimens and professional interpretation of results. Analysis charges will be incurred for total work performed, and generally include 2 banded karyograms and the analysis of 20 metaphase cells. If no metaphase cells are available for analysis, no analysis charges will be incurred. If additional analysis work is required, additional charges may be incurred.
The following algorithms are available in Special Instructions:
-Prenatal Aneuploidy Screening and Diagnostic Testing Options
-High-Risk Pregnancy Based on Abnormal Fetal Malformations: Laboratory Testing Algorithm
Special Instructions
Method Name
Cell Culture Followed by Chromosome Analysis
Reporting Name
Chromosomes, Amniotic FluidSpecimen Type
Amniotic FldAdvisory Information
Portions of the specimen may be used for other tests such as measuring markers for neural tube defects (eg, AFPA / Alpha-Fetoprotein, Amniotic Fluid), molecular genetic testing, biochemical testing, and FISH testing (including PADF / Prenatal Aneuploidy Detection, FISH). If additional molecular genetic or biochemical genetic testing is needed, order CULAF / Amniotic Fluid Culture/Genetic Testing so that amniocyte cultures may be set up specifically for the use in these tests.
Shipping Instructions
Advise Express Mail or equivalent if not on courier service.
Necessary Information
Provide a reason for referral and gestational age with each specimen, and verify the specimen source. The laboratory will not reject testing if this information is not provided, but appropriate testing and interpretation may be compromised or delayed.
Specimen Required
Supplies: Refrigerate/Ambient Mailer, 5 lb (T329)
Specimen Type: Amniotic fluid
Submission Container/Tube: Centrifuge tube
Specimen Volume: 20-25 mL
Collection Instructions:
1. Optimal timing for specimen collection is during 14 to 18 weeks of gestation, but specimens collected at other weeks of gestation are also accepted.
2. Discard the first 2 mL of amniotic fluid.
3. Place the tubes in a Refrigerate/Ambient Mailer, 5 lb (T329).
4. Fill remaining space with packing material.
Additional Information:
1. Unavoidably, about 1% to 2% of mailed-in specimens are not viable.
2. If the specimen does not grow in culture, you will be notified within 7 days of receipt.
3. Bloody specimens are undesirable.
Supplies: Refrigerate/Ambient Mailer, 5 lb (T329)
Specimen Type: Fetal body fluid
Container/Tube: Sterile tube
Specimen Volume: Entire specimen
Collection Instructions:
1. Place the tubes in a Refrigerate/Ambient Mailer, 5 lb (T329).
2. Fill remaining space with packing material.
Additional Information:
1. If the specimen does not grow in culture, you will be notified within 7 days of receipt.
2. Clearly indicate on tube and paperwork that specimen is fetal body fluid.
Specimen Minimum Volume
Amniotic Fluid: 12 mL; Fetal Body Fluid: NA; If ordering in conjunction with other testing: If ordered with PADF: 14 mL, with CMAP: 24 mL, with PADF and CMAP: 26 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Amniotic Fld | Refrigerated (preferred) | |
| Ambient | ||
Clinical Information
Chromosome analysis for prenatal diagnosis is appropriate in pregnancies with abnormal maternal screening, advanced maternal age, and features suggestive of or concerns for aneuploidy syndromes, including Down syndrome, Turner syndrome, Klinefelter syndrome, trisomy 13 syndrome, and trisomy 18 syndrome.
Chromosomal abnormalities are the cause of a wide range of disorders associated with birth defects and congenital diseases. Many of these disorders can be diagnosed prenatally by analysis of amniocytes. This method permits diagnosis of chromosome abnormalities during the second trimester of pregnancy or later.
A chromosomal microarray (CMAP / Chromosomal Microarray, Prenatal, Amniotic Fluid/Chorionic Villus Sampling) is recommended, rather than chromosomal analysis, to detect clinically relevant gains or losses of chromosomal material in pregnancies with 1 or more major structural abnormalities. Chromosomal microarray can also be considered, rather than chromosome analysis, for patients undergoing invasive prenatal diagnostic testing with a structurally normal fetus.
Reference Values
An interpretative report will be provided.
Interpretation
Cytogenetic studies on amniotic fluid are considered nearly 100% accurate for the detection of large fetal chromosome abnormalities. However, subtle or cryptic abnormalities involving microdeletions usually can be detected only with the use of targeted FISH testing.
Approximately 3% of amniotic fluid specimens analyzed are found to have chromosome abnormalities. Some of these chromosome abnormalities are balanced and may not be associated with birth defects.
A normal karyotype does not rule out the possibility of birth defects, such as those caused by submicroscopic cytogenetic abnormalities, molecular mutations, and other environmental factors (ie, teratogen exposure). For these reasons, clinicians should inform their patients of the technical limitations of chromosome analysis prior to performing the amniocentesis.
It is recommended that a qualified professional in Medical Genetics communicate all results to the patient.
Clinical Reference
1. American College of Obstetricians and Gynecologists Committee on Genetics: Committee Opinion No. 581: the use of chromosomal microarray analysis in prenatal diagnosis. Obstet Gynecol 2013;122:1374-1377
2. Society for Maternal-Fetal Medicine (SMFM): The use of chromosomal microarray for prenatal diagnosis. Am J Obstet Gynecol. 2016;215:B2-B9
3. Committee Opinion, 640: Cell-free DNA screening for fetal aneuploidy. American College of Obstetricians and Gynecologists Committee on Genetics. Obstet Gynecol 2015;123:e31-e37
4. Wilson KL, Czerwinski JL, Hoskovec JM, et al: NSGC practice guideline: prenatal screening and diagnostic testing options for chromosome aneuploidy. J Genet Couns 2013;22:4-15
Day(s) and Time(s) Performed
Samples processed Monday through Sunday. Results reported Monday through Friday; 8 a.m.-5 p.m., CST.
Analytic Time
10 daysTest Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.CPT Code Information
88235, 88291-Tissue culture for amniotic fluid or chorionic villus cells, Interpretation and report
88269 w/modifier 52-Chromosome analysis, in situ for amniotic fluid cells, <6 colonies, 1 karyotype with banding (if appropriate)
88269-Chromosome analysis, in situ for amniotic fluid cells, 6 or greater colonies, 1 karyotype with banding (if appropriate)
88267, 88285–Chromosome analysis, amniotic fluid or chorionic villus, greater than 15 cells, 1 karyotype with banding (if appropriate)
88267 w/modifier 52-Chromosome analysis, amniotic fluid or chorionic villus, <15 cells, 1 karyotype with banding (if appropriate)
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CHRAF | Chromosomes, Amniotic Fluid | 62351-2 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 52297 | Result Summary | 50397-9 |
| 52299 | Interpretation | 69965-2 |
| 52298 | Result | 82939-0 |
| CG765 | Reason for Referral | 42349-1 |
| CG766 | Specimen | 31208-2 |
| 52300 | Source | 31208-2 |
| 52302 | Method | 49549-9 |
| 52301 | Banding Method | 62359-5 |
| 54640 | Additional Information | 48767-8 |
| 52303 | Released By | 18771-6 |
Forms
New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available in Special Instructions:
-Informed Consent for Genetic Testing (T576)
-Informed Consent for Genetic Testing-Spanish (T826)
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