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Test 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

Method Name

Cell Culture Followed by Chromosome Analysis

Reporting Name

Chromosomes, Amniotic Fluid

Specimen Type

Amniotic Fld


Advisory 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 days

Test 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 In Process

 

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 No LOINC Needed

Forms

New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (T576) is available in Special Instructions.

Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

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