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23216 Chromosome Analysis, Amniotic F (CHRAF)

Chromosome Analysis, Amniotic F (CHRAF)
Test Code: AFCASO
Synonyms/Keywords
​Ref Lab Code: 8426, Chromosome Analysis, Amniotic Fluid, Down Syndrome, Karyotype, Amniotic Fluid, Prenatal Diagnosis, Trisomy 21,
Amniotic Fluid, Chromosome Analysis, Prenatal Chromosomes, Amniotic Fluid
Useful For
Prenatal diagnosis of chromosome abnormalities (trisomies, deletions, translocations, etc)
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
Amniotic Fluid​ Centrifuge Tube​ ​20-25 mL 10 mL​
​Fetal body fluid ​Sterile Tube ​Entire Specimen ​N/A
Collection Processing Instructions

​Amniotic Fluid:

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.
Additional Information:
1. Place the tube in a Styrofoam container (Supply T329). Fill remaining space with packing material.
2. Unavoidably, about 1% to 2% of mailed-in specimens are not viable. If the specimen does not grow in culture, you will be notified within 7 days of receipt.
3. Bloody specimens are undesirable.
 
Fetal body fluid:
1. Place the tube in a Styrofoam container (Supply T329). Fill remaining space with packing material.
2. If the specimen does not grow in culture, you will be notified within 7 days of receipt.
3. Clearly indicate on tube and paperwork that specimen is fetal body fluid.
Specimen Stability Information
Specimen Type Temperature
​Amniotic Fluid ​ ​Refrigerated (preferred)
​Ambient
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation

Mayo Medical Laboratories​

Monday through Friday; 6am-9pm
 
Saturday, Sunday; 6am-4pm​
10 days​
Includes 2 banded karyograms, analysis of 15 or more metaphases, and other techniques when required. Results are usually confirmed in 15 or more colonies from 3 or more primary cultures. ​
Reference Lab
Test 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.
 
Portions of the specimen may be used for other tests such as measuring markers for neural tube defects (eg, AFPA/9950 Alpha-Fetoprotein, Amniotic Fluid), molecular genetic testing, biochemical testing, and FISH testing (including PAD/81424 Prenatal Aneuploidy Detection, FISH). If additional molecular genetic or biochemical genetic testing is needed, order AFC/80334 Amniotic Fluid Culture for Genetic Testing so that amniocyte cultures may be set up specifically for the use in these tests.
 
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. Amniotic fluid can be safely collected after 12 weeks of gestation, although for optimal cell growth, collection from 14 to 18 weeks of gestation is preferred. This method permits diagnosis of chromosome abnormalities during the second trimester of pregnancy or later.
 
The most common reasons for cytogenetic studies for prenatal diagnosis include advanced maternal age, abnormal maternal serum screen, a previous child with a chromosome abnormality, abnormal fetal ultrasound, or a family history of a chromosome abnormality.
Reference Range Information
46,XX or 46,XY. No apparent chromosome abnormality.
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.
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​88291

​1

​Interpretation and report
​88235 ​2 ​Culture 03
​88267 ​1 ​Metaphases, <15 ​If needed
​88267 ​1 ​Metaphases, 15 ​If needed
​88267 ​2 ​Metaphases, >15 ​If needed
​88285 ​1 ​Metaphases, >15 ​If needed
​88269 ​1 ​Colonies, 1-5 ​If needed
​88269 ​1 ​Colonies, 6+ ​If needed
​88283 ​1 ​Ag-Nor/CBL Stain ​If needed
​88280 ​1 ​Karyotypes, >1 ​If needed
Synonyms/Keywords
​Ref Lab Code: 8426, Chromosome Analysis, Amniotic Fluid, Down Syndrome, Karyotype, Amniotic Fluid, Prenatal Diagnosis, Trisomy 21,
Amniotic Fluid, Chromosome Analysis, Prenatal Chromosomes, Amniotic Fluid
Ordering Applications
Ordering Application Description
​Centricity ​Amnio Chromosome Analysis
​Cerner ​Chromosome Analysis, Amniotic Fluid (AF)
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
Amniotic Fluid​ Centrifuge Tube​ ​20-25 mL 10 mL​
​Fetal body fluid ​Sterile Tube ​Entire Specimen ​N/A
Collection Processing

​Amniotic Fluid:

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.
Additional Information:
1. Place the tube in a Styrofoam container (Supply T329). Fill remaining space with packing material.
2. Unavoidably, about 1% to 2% of mailed-in specimens are not viable. If the specimen does not grow in culture, you will be notified within 7 days of receipt.
3. Bloody specimens are undesirable.
 
Fetal body fluid:
1. Place the tube in a Styrofoam container (Supply T329). Fill remaining space with packing material.
2. If the specimen does not grow in culture, you will be notified within 7 days of receipt.
3. Clearly indicate on tube and paperwork that specimen is fetal body fluid.
Specimen Stability Information
Specimen Type Temperature
​Amniotic Fluid ​ ​Refrigerated (preferred)
​Ambient
Useful For
Prenatal diagnosis of chromosome abnormalities (trisomies, deletions, translocations, etc)
Reference Range Information
46,XX or 46,XY. No apparent chromosome abnormality.
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.
For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation

Mayo Medical Laboratories​

Monday through Friday; 6am-9pm
 
Saturday, Sunday; 6am-4pm​
10 days​
Includes 2 banded karyograms, analysis of 15 or more metaphases, and other techniques when required. Results are usually confirmed in 15 or more colonies from 3 or more primary cultures. ​
Reference Lab
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​88291

​1

​Interpretation and report
​88235 ​2 ​Culture 03
​88267 ​1 ​Metaphases, <15 ​If needed
​88267 ​1 ​Metaphases, 15 ​If needed
​88267 ​2 ​Metaphases, >15 ​If needed
​88285 ​1 ​Metaphases, >15 ​If needed
​88269 ​1 ​Colonies, 1-5 ​If needed
​88269 ​1 ​Colonies, 6+ ​If needed
​88283 ​1 ​Ag-Nor/CBL Stain ​If needed
​88280 ​1 ​Karyotypes, >1 ​If needed
For most current information refer to the Marshfield Laboratory online reference manual.