Rh (D) Immunoglobulin (Anti-D)

Guidelines for the use of Rh(D) Immunoglobulin (Anti-D).

Educational Resource Area

Visit our Stage 3 Rh(D) Immunoglobulin Routine Prophylaxis Program resource area for more information and a range of support materials available to download or order on the latest guidelines for the use of Rh(D) immunoglobulin (Anti-D).

In pregnant women with Rh(D) negative blood group
and no pre-existing Anti-D antibodies

• Rh(D) Immunoglobulin should be administered as soon as possible after the sensitising event, but always within 72 hrs for successful immunoprophylaxis.
• If Rh(D) Immunoglobulin has not been administered within 72 hrs, a dose offered within up to 9-10 days may provide protection.
• Rh(D) Immunoglobulin should not be given to women with preformed anti-D antibodies, except where the preformed anti-D is due to the antenatal administration of Rh(D) Immunoglobulin.
• Rh(D) Immunoglobulin 100 IU is sufficient to protect against a Fetomaternal Haemorrhage (FMH) of 1.0 mL of fetal red cells (2.0 mL whole blood).
• Quantify the magnitude of the FMH following a sensitising event (including delivery) to ensure an adequate dose of Rh(D) Immunoglobulin is offered as more than one dose may be required.
• Tests to assess the volume of FMH include but are not limited to the Kleihauer-Betke acid elution test and flow cytometry.
• The majority of fetal bleeds are less than 5 mL of red blood cells.
  
  • In about 50% of cases, FMH is less than 0.05 mL
  • In about 5% of cases, FMH is greater than 0.5 mL
  • In about 3% of cases, FMH is greater than 1 mL
  • In up to 0.6% of cases, FMH is 30 mL or greater.

Sensitising events include (2):

• normal delivery
• ectopic pregnancy
• miscarriage
• termination of pregnancy
• invasive prenatal diagnostic procedures (including chorionic villus sampling, amniocentesis and cordocentesis)
• abdominal trauma considered sufficient to cause fetomaternal haemorrhage
• external cephalic version
• antepartum haemorrhage.

The batch number of every vial of human immunoglobulin administered must be recorded in the patient’s medical history and in accordance with other legal statutory requirements.

**In some circumstances, access to an intravenous preparation may be warranted. A quantity of intravenous Rh(D) immunoglobulin (WinRho SDFTM) will be available for this purpose. Contact ARCBS in your capital city for more information.

Approximately 17% of pregnant Caucasian women will be Rh(D) negative, and their babies (if Rh(D) positive) may be at risk of developing Haemolytic Disease of the Newborn (HDN) due to Rh(D) incompatibility.(2)

Antibody formation occurs during pregnancy in 1.5% of Rh (D) negative women carrying a Rh(D) positive infant, despite use of postnatal prophylaxis.(2)

The rate of antibody formation can be reduced to 0.2% or less by the administration of Rh(D) Immunoglobulin during pregnancy, at 28 weeks and 34 weeks (antenatal prophylaxis), as well as after delivery.(2)

Presentation

Single vials containing 625IU or 250IU anti-D antibody.

Contraindications

Should not be given to:

• An Rh(D) positive or Du positive individual
• An Rh(D) negative or Du positive individual previously sensitised to Rh(D) antigen. Note: Although there is no benefit in administering Rh (D) immunoglobulin to a woman who is already sensitised to Rh factor, there is no more risk than when it is given to a woman who is not sensitised.
• Individuals with IgA deficiency – unless they have no circulating anti IgA antibodies.
• Individuals with severe thrombocytopenia or coagulation disorder that would contraindicate IM injections.

Precautions

MUST NOT be administered intravenously.

Give with caution to patients with a history of prior systemic allergic reactions to human immunoglobulin preparations.

Must not be given to Rh(D) positive postpartum infants. Babies born of women given Rh(D) Immunoglobulin antepartum may have a weakly positive Coombs’ test at birth.

Availability

Requests to ARCBS. Some hospitals may hold stocks.

Dosage and Administration

Dosage as outlined above per NHMRC best practice Guidelines.

Administer by slow intramuscular injection using large gauge needle (20g). If a large dose (more than 5 mL) is required, it is advisable to administer it in divided doses at different sites. Suitable local anaesthetic may be added if desired.

The product s does not contain antimicrobial preservative; it must be used immediately after opening the vial.

Note: Supplies of suitable plasma for Rh(D) Immunoglobulin production are scarce. Individuals who have Rh(D) antibodies should be urged to enrol as voluntary blood donors.

References

(1) Communication from Professor Richard Smallwood, Chief Medical Officer,
Commonwealth of Australia (November 2005).

(2) NHMRC Guidelines on the prophylactic use of Rh(D) Immunoglobulin (Anti-D)
in obstetrics 2003; http://www.nba.gov.au/pubs/pdf/glines-anti-d.pdf

Refer to the current product sheet for further information.