Fetal RHD screen

Clinical Background:

D negative women who carry a D positive fetus may produce antibodies to the fetal D antigens after a fetomaternal haemorrhage or birth. Such antibodies may cross the placenta in future pregnancies and can cause haemolytic disease if the fetus is D positive. Traditionally, routine antenatal prophylaxis has been offered to all D negative women to reduce the incidence of haemolytic disease, and additionally women are offered anti-D if they have any sensitising events. Approximately 40% of D negative mothers will carry a D negative baby and hence are not a risk of alloimmunisation and HDFN caused by anti-D antibodies. These women do not require RAADP and as such are exposed to a product of human origin unnecessarily. NHSBT IBGRL have developed a non-invasive molecular technique, which uses a maternal sample to detect free fetal DNA (FFDNA) in maternal plasma. Testing is possible from 11 weeks gestation. D negative women who accept the offer of FFDNA testing will have an additional blood test, ideally at about 16 weeks of pregnancy which will identify the fetal D status. Those women who are carrying a D negative baby could avoid unnecessary treatment with anti-D immunoglobulin. Those women who are carrying a D positive baby can make an informed choice about whether to have treatment with anti-D immunoglobulin. Women must have immune anti-D antibodies for this test.

Discipline:

Transfusion

Transfusion
Specimen Container Adult:

Minimum of 6mL EDTA

Minimum of 6mL EDTA
Specimen Container Paediatric:

N/A

N/A
Minimum Volume Adult:

6mL

6mL
Minimum Volume Paediatric:

N/A

N/A
Special Requirement:

Specific NHSBT FFDNA Form (5197/2.1) must be completed. EDD must be present on request form.
Sample must be HANDWRITTEN and be sent with a signed request form.

Specific NHSBT FFDNA Form (5197/2.1) must be completed. EDD must be present on request form.
Sample must be HANDWRITTEN and be sent with a signed request form.
Sample Stability:

Short term storage: 24 hours at room temperature. Long term storage: 7 days at 4-6°C

Short term storage: 24 hours at room temperature. Long term storage: 7 days at 4-6°C
Transport Requirements:

Sample should be transported to Laboratory Medicine Reception via GP courier, hospital air-tube system or hand delivered to maintain storage conditions. Samples must not be subjected to extreme hot...

Sample should be transported to Laboratory Medicine Reception via GP courier, hospital air-tube system or hand delivered to maintain storage conditions. Samples must not be subjected to extreme hot or cold conditions prior to testing.
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Add On Test:

N/A

N/A
Interpretation:

If maternal D status is D NEGATIVE and the Fetal RHD typing predicts that this fetus is D POSITIVE, RAADP (anti-D prophylaxis) is indicated unless maternal allo anti-D is present.
If maternal D stat...

If maternal D status is D NEGATIVE and the Fetal RHD typing predicts that this fetus is D POSITIVE, RAADP (anti-D prophylaxis) is indicated unless maternal allo anti-D is present.
If maternal D status is D NEGATIVE and the Fetal RHD typing predicts that this fetus is D NEGATIVE, RAADP (anti-D prophylaxis) IS NOT required in this pregnancy
If the maternal D status is D NEGATIVE and the Fetal RHD typing is INCONCLUSIVE, the pregnancy is managed as if the fetus is D POSITIVE and anti-D prophylaxis is indicated unless maternal allo anti-D is present.
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Other Info:

This test is referred to NHSBT by the Transfusion laboratory.

This test is referred to NHSBT by the Transfusion laboratory.
Routine Contact Name:

FH Section Leads
RVI Section Leads
Routine Telephone:

Freeman: 0191 213 7849
RVI: 0191 282 4335

Freeman: 0191 213 7849
RVI: 0191 282 4335
Specialist Test:

Yes

Yes
Specialist Contact Name:

Transfusion manager

Transfusion manager
Specialist Telephone:

0192 213 9169

0192 213 9169

Fetal RHD screen

Clinical Background:

Test Details

Availability:

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