ARUP's Laboratory Test Directory

RhD Antigen (RhD) Genotyping : 0051368
[ image for: Patient History for Fetal Molecular Testing]
Patient History for Fetal Molecular Testing
  


Mnemonic: RHD

Methodology: Polymerase Chain Reaction/Fluorescence Monitoring
Performed: Mon, Thu
Reported: 2-7 days
Specimen Required: Collect: and Transport: Cultured cells: Two T-25 flasks at 80% confluent of cultured amniocytes. Fill flasks with culture media to ship at 20-25°C. Backup cultures must be retained at the client's institution until testing is complete. If the client is unable to culture amniocytes, this can be arranged by contacting ARUP Client Services at (800) 522-2787.
Maternal sample: One 3 mL whole blood, lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B) at 20-25°C.
Amniotic fluid: 10 mL unspun fluid at 20-25°C. (Min: 5 mL)

Storage/Transport Temperature:

Remarks: Fetal specimens are CRITICAL AMBIENT and must be received within 48 hours of shipment due to liability of cells. Maternal specimen is recommended for proper testing interpretation. Order Maternal Cell (MCC MAT) (0050608).
Patient History Form is available on the ARUP Web site or by contacting ARUP Client Services.

Stability (collection to initiation of testing): Fetal: Ambient: 2 days; Refrigerated: Unacceptable; Frozen: Unacceptable
Maternal: Ambient: 3 days; Refrigerated: 1 week; Frozen: Unacceptable
Reference Interval:
By report
Interpretive Data: Background Information for RhD Antigen (RhD) Genotyping:
Characteristics: Fetal or neonatal erythroblastosis and hydrops.
Incidence of Rhd negative genotype: 15% Caucasians, 5% African Americans, less than 1% Asians
Inheritance: Autosomal recessive
Cause: Maternal-fetal Rh D antigen incompatibility
Methods: Determine the presence of the RHD exons 5, 7, and a 37 base pair insertion in the intron 3/exon 4 boundary by PCR and fluorescence monitoring.
Allelic height ratios are used to determine the number of copies of RHD as compared to RHCE.
Limitations: Bloody amniotic fluid specimens may give false-negative results because of maternal cell contamination; specificity may be compromised by mutations in primer sites or those outside the RHD exons examined; fetuses predicted to be unaffected should continue to be monitored by noninvasive means.
Analytic Sensitivity and Specificity: Greater than 99%
Clinical Sensitivity: Greater than 98%

For quality assurance purposes, ARUP Laboratories will provide a confirmation of the above result at no charge. Following delivery, please collect a cord blood sample from the infant in a lavender (EDTA) or yellow (ACD Solution A or B) top tube and transport 1mL cord blood at 2-8 °C. Please specify on the test request form that this is a confirmatory study to be performed at no charge. Please provide the mother's name for specimen identification purposes.

This test is performed pursuant to an agreement with Roche Molecular Systems, Inc.



Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.

Please refer to Statement C in the Compliance Statements section in the front of the Laboratory Test Directory.
Note: For Amniotic Specimens: For the Delta OD 450 nm, refer to Amniotic Bilirubin Scan (0080276). Whole blood is acceptable for paternal specimens.
CPT Code(s): 83891 Isolation; 83898 x3 Amplification; 83896 x6 Nucleic acid probes; 83912 Interpretation and report Additional CPT code modifiers may be required for procedures performed to test for oncologic or inherited disorders.
Cross References: RHD Gene
 
 

 

 

 
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