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| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
RHD Gene Detection, Fetal
Test Code16592
Preferred Specimen
**This test is not available for New York patient
testing.**
Reject Criteria:
Clotted; Streck tubes; Pregnancy before 10 weeks
PREFERRED
10 mL whole blood (L, lavender-top tube, EDTA), room
temperature
Minimum: 5 mL
RT: 6 days
Refrigerated (cold packs): Unacceptable
Frozen: Unacceptable
testing.**
Reject Criteria:
Clotted; Streck tubes; Pregnancy before 10 weeks
PREFERRED
10 mL whole blood (L, lavender-top tube, EDTA), room
temperature
Minimum: 5 mL
RT: 6 days
Refrigerated (cold packs): Unacceptable
Frozen: Unacceptable
Minimum Volume
5 mL
Transport Container
Lavender Top EDTA Tube
Transport Temperature
Room Temperature
Specimen Stability
Room Temperature: 6 days
Refrigerated: Unacceptable
Frozen: Unacceptable
Refrigerated: Unacceptable
Frozen: Unacceptable
Methodology
Real-Time RT-PCR
Setup Schedule
Monday-Sunday Morning
Report available: 6 Days
Report available: 6 Days
Reference Range
See Laboratory Report
Clinical Significance
This test offers molecular detection by real-time PCR of
the RHD gene in fetal cell-free DNA (cfDNA) isolated from
maternal plasma. In RhD-negative pregnant persons, this
test can help determine the fetal RhD status to assess
risk for RhD alloimmunization-associated hemolytic
disease of the fetus and newborn (HDFN). As this is a
screening test, it is not intended to be used for
diagnostic purposes.
If cfDNA testing results suggest an RhD-negative fetus,
Rh immune globulin (RhIG) may not need to be routinely
administered, but such determination should be based on
clinical judgement and current peer reviewed guidelines
[1].
Although rare, false positive or false negative results
may occur. A fetus with a positive RhD result may present
with an RhD-negative phenotype due to a variant in the
RHD gene undetected by this screening assay. Detection of
a weak fetal RHD genotype may generate a false positive
RhD result in a fetus that may present with an RhD
negative phenotype at birth.
This test cannot distinguish between a positive RHD
genotype and a negative RhD phenotype in the presence of
RHD pseudogene interference. All results should be
interpreted in the context of pertinent clinical
findings, relevant obstetric history and laboratory data
based on a clear understanding of the value and
limitations of the test data.
References
1. ACOG Clinical Practice Update: Paternal and Fetal
Genotyping in the Management of Alloimmunization in
Pregnancy. Obstetrics & Gynecology. 2024; 144(2): p
e47-e49.
the RHD gene in fetal cell-free DNA (cfDNA) isolated from
maternal plasma. In RhD-negative pregnant persons, this
test can help determine the fetal RhD status to assess
risk for RhD alloimmunization-associated hemolytic
disease of the fetus and newborn (HDFN). As this is a
screening test, it is not intended to be used for
diagnostic purposes.
If cfDNA testing results suggest an RhD-negative fetus,
Rh immune globulin (RhIG) may not need to be routinely
administered, but such determination should be based on
clinical judgement and current peer reviewed guidelines
[1].
Although rare, false positive or false negative results
may occur. A fetus with a positive RhD result may present
with an RhD-negative phenotype due to a variant in the
RHD gene undetected by this screening assay. Detection of
a weak fetal RHD genotype may generate a false positive
RhD result in a fetus that may present with an RhD
negative phenotype at birth.
This test cannot distinguish between a positive RHD
genotype and a negative RhD phenotype in the presence of
RHD pseudogene interference. All results should be
interpreted in the context of pertinent clinical
findings, relevant obstetric history and laboratory data
based on a clear understanding of the value and
limitations of the test data.
References
1. ACOG Clinical Practice Update: Paternal and Fetal
Genotyping in the Management of Alloimmunization in
Pregnancy. Obstetrics & Gynecology. 2024; 144(2): p
e47-e49.
