Test ID: PAD
Prenatal Aneuploidy Detection, FISH
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Ruling out aneuploidy of chromosomes 13, 18, 21, X, and Y in a rapid, cost-efficient manner
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
Fluorescence In Situ Hybridization (FISH)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Chromosome Analysis Consultation,PAD
Down Syndrome
Edward's Syndrome
FISH (Fluorescent In Situ Hybridization)
FISH 13,18,21,X,Y
FISH Amniotic Fluid
FISH for Ambiguous Genitalia
FISH for PAD
FISH for Prenatal Aneuploidy
FISH for Prenatal Aneusomy
FISH, Prenatal Aneuploidy Detection
FISH, Rule Out Down Syndrome
FISH, Rule Out Edwards Syndrome
FISH, Rule Out Klinefelter Syndrome
FISH, Rule Out Patau Syndrome
FISH, Rule Out Trisomy 13/ Trisomy 18/ or Trisomy 21
FISH, Rule Out XXY, XXX, or XYY
FISH, Turner Syndrome
Klinefelter Syndrome
Patau Syndrome
Prenatal Aneuploidy Detection (PAD)
Prenatal Aneuploidy Detection, FISH
Prenatal Aneusomy Detection (PAD)
Turner Syndrome
XXY, XXX, OR XYY
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
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.
Forms:
1. 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 (Supply T576) is available in Special Instructions.
2. If not ordering electronically, submit a Cytogenetics/AFP Congenital Disorders Request Form (Supply T238) with the specimen.
Advise Express Mail or equivalent if not on courier service.
Submit only 1 of the following specimens:
Preferred:
Specimen Type: Amniotic fluid
Container/Tube: Amniotic fluid container
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. Provide gestational age at the time of amniocentesis.
2. Discard the first 2 mL of amniotic fluid.
Additional Information:
1. Place the tubes in a Styrofoam container (Supply T329).
2. Fill remaining space with packing material.
3. Unavoidably, about 1% to 2% of mailed-in specimens are not viable.
4. Bloody specimens are undesirable.
5. If the specimen does not grow in culture, you will be notified within 7 days of receipt.
6. Results will be reported and also telephoned or faxed, if requested.
Acceptable:
Specimen Type: Chorionic villi
Container/Tube: 15-mL tube containing 15 mL of transport media
Specimen Volume: 20-30 mg
Collection Instructions:
1. Collect specimen by the transabdominal or transcervical method.
2. Transfer chorionic villi to a Petri dish containing transport medium.
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 Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Refrigerated (preferred) | |
| Ambient | ||
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Approximately 1/2 of clinically recognizable spontaneous abortions have a major chromosomal anomaly.
Up to 95% of chromosomal abnormalities diagnosed prenatally involve aneuploidy (gain or loss of whole chromosome) of chromosomes 13, 18, 21, X, and Y.
In liveborn infants, about 8/1,000 have a major chromosome anomaly, of which 6.5/1,000 involve aneuploidy of these 5 chromosomes. Therefore, aneuploidy of chromosomes 13, 18, 21, X, and Y accounts for 81% to 95% of major chromosome anomalies in liveborn infants.
Techniques to detect aneuploidy include standard chromosome analysis and FISH. Standard chromosome analysis from amniotic fluid cells or chorionic villi requires 5 to 9 days for culture, harvest, and analysis. FISH, which uses DNA probes and can be performed on cultured and uncultured cells, can rapidly detect aneuploidy of 13, 18, 21, X, and Y in uncultured amniotic fluid cells or chorionic villi. FISH-based analysis may be helpful in medically urgent evaluations of newborn infants suspected to have aneuploidy of 1 of these chromosomes.
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 interpretive report will be provided.
Interpretation Provides information to assist in interpretation of the test results
An interpretive report is provided.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test does not detect aneuploidy of chromosomes other than 13, 18, 21, X, or Y. This test does not detect other chromosomal or structural anomalies.
Low levels of mosaicism involving chromosomes 13, 18, 21, X, or Y may not be detected by this procedure.
There may be interpretation problems in cases of maternal cell contamination.
The use of these probes has been approved by the FDA as a stand-alone test. However, we would strongly recommend that a complete chromosome analysis or a detailed ultrasound be performed in conjunction with this diagnostic procedure. In cases where the FISH analysis is normal, a chromosome analysis allows identification of more complex abnormalities and the less common numeric abnormalities of other chromosomes. In cases where the FISH study is abnormal, chromosome analysis can determine whether the abnormality is due to aneuploidy or a complex structural abnormality. Conventional chromosome analysis allows calculation of a more accurate recurrence risk for the family.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Maeda T, Ohno M, Matsunobu A, et al: A cytogenetic survey of 14,835 consecutive liveborns. Jap J Hum Genet 1991;36:117-129
2. Whiteman DAH, Klinger K: Efficiency of rapid in situ hybridization methods for prenatal diagnosis of chromosome abnormalities causing birth defects. Am J Hum Genet 1991;49:A1279
3. Ward BE, Gersen SL, Carelli MP, et al: Rapid prenatal diagnosis of chromosomal aneuploidies by fluorescence in situ hybridization: Clinical experience with 4,500 specimens. Am J Hum Genet 1993;52:854-865
Method Description Describes how the test is performed and provides a method-specific reference
The FISH test is based on commercially available, directly-labeled, multicolored fluorescent DNA probes that are centromere-specific for chromosome 18, X, and Y, and locus-specific for 13q14 and 21q22.13-q22.2. These 5 probes are used for detection of aneuploidy for 13, 18, 21, X, or Y from 2.0 mL to 4.0 mL of uncultured amniotic fluid cells or from 1.0 mg to 3.0 mg of chorionic villi. A total of 200 cells are analyzed by 2 technologists for each probe. This FISH test can be performed on any tissue, but uncultured amniotic fluid cells or chorionic villi are preferred. Specimens with 2 signals for probes on chromosomes 13, 18, and 21, and either 1 X and 1 Y signal (male) or 2 X signals (female) are considered normal. Specimens with signal patterns other than 2 signals for 13, 18, and 21, and XX or XY are consistent with loss or gain of the locus in question. (Jalal SM, Law ME, Carlson RO, et al: Prenatal detection of aneuploidy by direct labeled multicolored probes and interphase fluorescence in situ hybridization. Mayo Clin Proc 1998;73:132-137)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Samples processed Monday through Sunday. Results reported Monday through Friday, 8 a.m.-5 p.m. CST.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
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 The location of the laboratory that performs the test
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's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
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 Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
88271 x 5-DNA probe, each
88275-Interphase in situ hybridization
88291-Interpretation and report
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 16302 | Specimen | 31208-2 |
| 16351 | Specimen ID | N/A |
| CG331 | Source | N/A |
| 16303 | Order Date | N/A |
| CG334 | Reason For Referral | 42349-1 |
| 16304 | Method | In Process |
| 16306 | Results | In Process |
| 16307 | Interpretation | 69965-2 |
| 16308 | Amendment | N/A |
| 16309 | Consultant | N/A |
| 16310 | Report Date | N/A |
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