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Free Foetal DNA (ffDNA)

During pregnancy after 12 weeks of gestation, a small amount of foetal DNA can be found in the maternal circulation. This DNA can be tested to predict the babys Rh(D) status using polymerase chain reaction. Knowing the baby’s Rh(D) status is useful in Rh(D) Negative pregnant women who have not formed their own immune anti-D as it determines whether or not they will require anti-D prophylaxis throughout the pregnancy.

A positive test means that the foetus is predicted to be Rh(D) Positive and in the case of twins, at least one foetus is Rh(D) Positive. These patients will require standard anti-D prophylaxis. A negative test means the foetus is predicted to be Rh(D) negative and anti-D prophylaxis is not required. A cord sample at delivery should still be tested in the negative test patients to confirm.

Sampling for ffDNA testing follows the same sampling guidelines as other transfusion samples with the added requirements that the date of venepuncture and EDD (scan) must be supplied. Testing is normally done at the 16 week appointment.

Testing is performed at the International Blood Grouping Reference Laboratory (IBGRL) in Bristol and takes about 14 days.

Results can be obtained from the national Blood Service sp-ICE server (first choice) and the contact number for the laboratory is 0117 921 7572.

Anti-D Prophylaxis

Anti-D immunoglobulin for Rh(D) prophylaxis is available from the Blood bank on each site for any Rh(D) Negative woman who has had a potentially sensitising episode, in accordance with current national guidelines.

• For sensitising episodes up to 20 weeks gestation, 500iu anti-D is administered. A Kleihauer test is not required.
• For sensitising episodes between 20 weeks and term, 1500iu anti-D is administered and a Kleihauer test performed.
• Anti-D prophylaxis is inappropriate for women who have formed immune anti-D.

Routine Antenatal Anti-D Prophylaxis (RAADP)

1500 iu (300mg) Rhophylac anti-D has been offered to all RH(D) Negative pregnant women in the Ä¢¹½tvÊÓƵ area (NICE guidelines – 2002) since April 2005. The Rhophylac immunoglobulin is administered i.v. at the 28 week antenatal check held at the LGI & SJUH Antenatal Clinics. Rh(D) negative women should be referred to the relevant clinic via their midwife. The 28 week blood grouping sample should be taken prior to the administration of Rhophylac to prevent interference with the antibody screen.

Please bear in mind that:

• Rh(D) Negative women should still be given a stat dose of anti-D if they have a further sensitising episode.
• Anti-D prophylaxis is inappropriate for women who have formed immune anti-D. 

Antenatal Contact Details

Antenatal Results

Results and General information is obtainable from the Bloodbank at the appropriate booking hospital:

LGI: 0113 3923398

SJUH: 0113 2065559 

Other Routine Antenatal Testing

The Haematology Laboratory (LGI) performs Full Blood Counts and Haemoglobinopathy Screens 0113 3922412

The Microbiology Laboratory (LGI) performs Syphilis, Hepatitis B & C, HIV, and Rubella tests 0113 3923499

The International Blood Grouping Reference Laboratory (IBGRL) performs ffDNA testing 0117 9217572