Test Id : CHRAF
Chromosome Analysis, Amniotic Fluid
Useful For
Suggests clinical disorders or settings where the test may be helpful
Prenatal diagnosis of chromosome abnormalities, including aneuploidy (ie, trisomy or monosomy) and balanced rearrangements
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Cultures from this specimen will be discarded 10 days after all cytogenetic test results have been reported. If additional testing is desired, call the laboratory at 800-533-1710.
Reflex Tests
Lists tests that may or may not be performed, at an additional charge, depending on the result and interpretation of the initial 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
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
This test is not appropriate as a first-tier test for detecting gains or losses of chromosomal material in pregnancies with 1 or more major structural abnormalities.
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.
Method Name
A short description of the method used to perform the test
Cell Culture followed by Chromosome Analysis
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
Amniotic Fluid, Chromosome Analysis
Chromosome Analysis, Amniotic Fluid
Karyotype, Amniotic Fluid
Prenatal Chromosomes, Amniotic Fluid
Fetal Aneuploidy
Fetal Chromosome Analysis
DNA Screening for Fetal Aneuploidy
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
This test is not appropriate as a first-tier test for detecting gains or losses of chromosomal material in pregnancies with 1 or more major structural abnormalities.
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.
Specimen Type
Describes the specimen type validated for testing
Amniotic Fld
Ordering Guidance
This test should be performed for prenatal diagnostic purposes only. 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.
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 fluorescence in situ hybridization testing (including PADF / Prenatal Aneuploidy Detection, FISH). If additional molecular genetic or biochemical genetic testing is needed, order CULAF / Culture for Genetic Testing, Amniotic Fluid so 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.
ORDER QUESTIONS AND ANSWERS
| Question ID | Description | Answers |
|---|---|---|
| CG765 | Reason for Referral | |
| CG766 | Specimen |
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Specimen Type: Amniotic fluid
Submission Container/Tube: Centrifuge tube
Specimen Volume: 20 to 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. If ordering with PADF / Prenatal Aneuploidy Detection, FISH, submit a minimum of 14 mL.
4. If ordering with CMAP / Chromosomal Microarray, Prenatal, Amniotic Fluid/Chorionic Villus Sampling, submit a minimum of 24 mL.
5. If ordering with both PADF and CMAP, then submit a minimum of 26 mL.
Additional Information:
1. Unavoidably, about 1% to 2% of mailed-in specimens are not viable.
2. If the specimen does not grow in culture, the client will be notified within 7 days of receipt.
3. Bloody specimens are undesirable.
Specimen Type: Fetal body fluid
Container/Tube: Sterile tube
Specimen Volume: Entire specimen
Additional Information:
1. If the specimen does not grow in culture, the client will be notified within 7 days of receipt.
2. Clearly indicate on tube and paperwork that specimen is fetal body fluid.
Special Instructions
Library of PDFs including pertinent information and forms related to the test
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:
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
The following are the minimum volumes when only this test is ordered:
Amniotic fluid: 12 mL
Fetal body fluid: See Specimen Required
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Amniotic Fld | Refrigerated (preferred) | ||
| Ambient | |||
Useful For
Suggests clinical disorders or settings where the test may be helpful
Prenatal diagnosis of chromosome abnormalities, including aneuploidy (ie, trisomy or monosomy) and balanced rearrangements
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Cultures from this specimen will be discarded 10 days after all cytogenetic test results have been reported. If additional testing is desired, call the laboratory at 800-533-1710.
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
This test is not appropriate as a first-tier test for detecting gains or losses of chromosomal material in pregnancies with 1 or more major structural abnormalities.
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.
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Chromosome analysis for prenatal diagnosis is appropriate in pregnancies with abnormal maternal screening or advanced maternal age and with clinical 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 one 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
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
An interpretative report will be provided.
Interpretation
Provides information to assist in interpretation of the test results
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/duplications usually can be detected only with the use of targeted fluorescence in situ hybridization testing or chromosomal microarray.
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, pathogenic molecular variants, 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.
Limitations:
-Abnormal results from amniotic fluid analysis may not represent fetal karyotype in all tissues.
-Only large abnormalities visible by manual inspection are detectable; subtle structural chromosome abnormalities may be missed
-Artifacts of cell culture may very rarely be misinterpreted as mosaicism in the sample.
It is recommended that a qualified professional in Medical Genetics communicate all results to the patient.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Interfering factors:
-Improper syringes or transport vessels may be unsuitable for amniotic cells. Amniotic fluid should not be exposed to the syringe plunger tip for longer than a few seconds, and fluid should be transferred to a transport (centrifuge) tube as soon as possible following collection.
-Transport time should not exceed 2 days.
-A bloody specimen may interfere with attempts to culture cells and contamination by maternal cells may cause interpretive problems.
-Inadequate amount of fluid may not permit adequate analysis.
-Improper packaging may result in broken, leaky, and contaminated specimen during transport.
-Exposure of the specimen to temperature extremes (freezing or >30 degrees C) may kill cells and severely interferes with attempts to culture cells.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
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(6):1374-1377
2. Society for Maternal-Fetal Medicine (SMFM). The use of chromosomal microarray for prenatal diagnosis. Am J Obstet Gynecol. 2016;215(4):B2-B9
3. Committee Opinion, 640. Cell-free DNA screening for fetal aneuploidy. Obstet Gynecol. 2015;126(3):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(1):4-15
Method Description
Describes how the test is performed and provides a method-specific reference
The specimen is centrifuged, and the cell pellet mixed with culture media, then split into up to 8 primary culture dishes using the In Situ Culture and Analysis (ISCA) method to establish cultures. Cells are harvested after 5 to 7 days. In the harvest process, the cells are exposed to ethidium bromide, colcemid, and hypotonic solution and fixed with glacial acetic acid and methanol. Metaphase preparations are routinely stained by G-banding, but other staining methods may be employed as needed. Fifteen metaphases from 15 colonies and 3 or more primary cultures usually are examined. In cases where true mosaicism is suspected, up to 30 colonies and up to 6 primary cultures may be analyzed. Minimal evidence for the presence of an abnormality is defined as 2 or more metaphases with the same structural abnormality, chromosome gain (trisomy), or 3 or more metaphases lacking the same chromosome. Five or more digitized images of metaphases are stored in computer-based imaging systems, and karyograms are prepared from 2 or more representative metaphases.( Arsham, Marilyn S., et al. editors. The AGT Cytogenetics Laboratory Manual. 4th ed. Wiley-Blackwell; 2017; Spurbeck JL, Carlson RO, Allen JE, Dewald GW. Culturing and robotic harvesting of bone marrow, lymph nodes, peripheral blood, fibroblasts, and solid tumors with in situ techniques. Cancer Genet Cytogenet. 1988;32(1):59-66)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Monday through Friday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Fees :
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
- Authorized users can sign in to Test Prices for detailed fee information.
- Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
- Prospective clients should contact their account representative. For assistance, contact Customer Service.
Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
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® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| CHRAF | Chromosomes, Amniotic Fluid | 62351-2 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| 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 | 85069-3 |
| 52301 | Banding Method | 62359-5 |
| 54640 | Additional Information | 48767-8 |
| 52303 | Released By | 18771-6 |