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Test ID: CHRCV Chromosome Analysis, Chorionic Villus Sampling

Useful For

Prenatal diagnosis of chromosome abnormalities, including aneuploidy (ie, trisomy or monosomy) and balanced rearrangements

 

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.

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
_KTG1 Karyotypes, >1 No, (Bill Only) No
_STAC Ag-Nor/CBL Stain No, (Bill Only) No

Testing Algorithm

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.

 

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, Chorionic Villus Samp

Specimen Type

Tissue


Advisory Information


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.

 

This test should be performed for prenatal diagnostic purposes only. Chromosome analysis on chorionic villus specimen (CVS) collected from products of conception (ie, stillbirth or miscarriage tissue) should be ordered as CHRPC / Chromosome Analysis, Autopsy, Products of Conception, or Stillbirth.



Shipping Instructions


Advise Express Mail or equivalent if not on courier service.



Necessary Information


Provide a reason for referral with each specimen. 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: CVS Media (RPMI) and Small Dish (T095)

Source: Chorionic villi

Container/Tube: 15-mL tube containing 15 mL of transport media

Specimen Volume: 20-30 mg

Collection Instructions:

1. Collect chorionic villus specimen (CVS) by the transabdominal or transcervical method.

2. Transfer the CVS to a Petri dish containing transport medium (Such as CVS Media (RPMI) and Small Dish [T095]).

3. Using a stereomicroscope and sterile forceps, assess the quality and quantity of the villi and remove any blood clots and maternal decidua.


Specimen Minimum Volume

12 mg; If ordering in conjunction with other testing: If ordered with PADF: 14 mg; with CMAP: 24 mg; with PADF and CMAP: 26 mg

Specimen Stability Information

Specimen Type Temperature Time
Tissue Refrigerated (preferred)
  Ambient 

Clinical Information

Although not used as widely as amniocentesis, the use of chorionic villus sampling (CVS) for chromosome analysis is an important procedure for the prenatal diagnosis of chromosome abnormalities. CVS can be collected by either transcervical or transabdominal techniques. The medical indications for performing chromosome studies on CVS are similar to amniocentesis, and may include advanced maternal age, abnormal first-trimester screen, and family history of a chromosome abnormality.

 

A chromosomal microarray (CMAP / Chromosomal Microarray, Prenatal) 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

An interpretive report will be provided.

Interpretation

Cytogenetic studies on chorionic villus specimen (CVS) are considered more than 99% reliable for the detection of most 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 CSVs 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 environmental factors (ie, teratogen exposure). For these reasons, clinicians should inform their patients of the technical limitations of chromosome analysis before the procedure is performed, so that patients may make an informed decision about pursuing the procedure.

 

Limitations:

-False-chromosome mosaicism may occur due to artifact of culture

-True mosaicism may be missed due to statistical sampling error

-Presence of chromosome abnormalities in placental cells that do not occur in the cells of the fetus (confined placental mosaicism)

-Subtle structural chromosome abnormalities can occasionally be missed

 

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

9 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

88267 w/modifier 52-Chromosome analysis, amniotic fluid or chorionic villus, <15 cells, 1 karyotype with banding (if appropriate)

88267-Chromosome analysis, amniotic fluid or chorionic villus, 15 cells, 1 karyotype with banding (if appropriate)

88267, 88285-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
CHRCV Chromosomes, Chorionic Villus Samp In Process

 

Result ID Test Result Name Result LOINC Value
52319 Result Summary 50397-9
52321 Interpretation 69047-9
52320 Result 82939-0
CG769 Reason for Referral 42349-1
52322 Specimen 31208-2
52323 Source 31208-2
52325 Method 49549-9
52324 Banding Method 62359-5
54624 Additional Information 48767-8
52326 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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