Rhesus D Immunoglobulin

The administration Anti-D has been shown to result in a significant reduction in the incidence of Rh isoimmunisation.

It is important to check Rhesus D antigen and antibody status in all with a negative blood group.

Anti D should be administered within 72 hours for successful immunoprophylaxis after the appropriate sentinel event. If this time frame is missed a dose up to 10 days may still provide some protection.

Blood should be taken from the mother before administration of the Rh D immunoglobulin to confirm her blood group and in more severe cases to assess the magnitude of foeto-maternal transfusion by Kleihauer testing, in order to determine if increased doses of anti-D are required.

Around 15% of women in Australia have a Rhesus-negative blood group, of which 40% will carry a Rhesus-negative baby.

Pathology

As little as 0.1 ml of Rh (D) positive foetal blood can result in maternal iso-immunization. ²

Preparations

Rh (D) Immunoglobulin-VF (for IM dosing):

• 250 IU the (50 mcg, “minidose”) protects against immunization of up to 2.5 mls of foetal red blood cells.
• 625 IU (or 125 mcg) protects against immunization of up to 6 mls of foetal red blood cells.

Rhophylac (human Anti-D CSL Behring) immunoglobulin solution for IV or IM injection.

• Glass syringe pre-filled with 1500 IU (300μg) 2mL solution for IV injection
• Dose in FMH: 1500 IU (300μg) vial will suppress the immunizing potential of <15mL of Rh (D) positive red cells.
• Maximum dose 15,000 IU (3000μg), independent of whether the transfusion volumes are  > 300mL of Rh (D) positive blood
• Administration: 2mL (1500 IU) per 15-60 seconds; within 72 hours of complication

The use of higher or further doses should be based on quantitative assessment of feto-maternal transfusion by Kleihauer test.

For haemorrhages greater than 6 mL, the recommended dose is 100 IU per mL Rh(D) positive red blood cells.

Indications

The indications for giving Anti D immunoglobulin for potentially sensitising events include:

All Rh (D) negative women (who have not actively formed their own Anti-D) should be offered Anti-D:

In the ED setting:

1. First Trimester: give 250 IU

• Ectopic Pregnancy
• Miscarriage (including cases of incomplete abortion and curettage):
  • Current KEMH guidelines recommend all non-sensitised rhesus negative women should receive anti-D immunoglobulin for threatened miscarriages
  • However, many sources state that there is insufficient evidence to suggest that a threatened miscarriage before 12 weeks gestation necessitates Anti-D. ¹

In cases of multiple (i.e twins or more) pregnancies where a sensitizing event occurs in the first trimester, give the 625 IU dose (rather than the 250 IU dose).

2. Beyond First Trimester: give 625 IU

• Abdominal trauma sufficient to cause feto-maternal transfusion
• Antepartum hemorrhages

If bleeding continues intermittently after 12 weeks, give Anti D Ig at 6 weekly intervals. ⁴

Outside the ED setting:

1. First Trimester: Give 250 IU

• Termination of pregnancy
• Chorionic villi sampling (genetic studies)

2. Beyond First Trimester: Give 625 IU:

• Amniocentesis/ cordocentesis (genetic studies)
• External cephalic version of a breech presentation, (whether successful or not).
• Routine antenatal dosing for Rh negative mothers:
  • All Rh (D) negative women (who have not actively formed their own Anti-D) at approximately 28 weeks gestation and again at approximately 34 weeks gestation.
  • Post-natally, within 72 hours: all women who deliver an Rh (D) positive baby should have quantification of feto-maternal haemorrhage to guide the appropriate dose of anti-D prophylaxis.

Contraindications/ Precautions

1. Women with preformed anti-D antibodies, except where the preformed Anti-D is due to the antenatal administration of Rh (D) immunoglobulin. If there is doubt, administer Rh (D) immunoglobulin.
2. An Rh(D) positive individual.
3. Use caution in patients with a history of prior systemic allergic reactions following the             administration of human immunoglobulin preparations.

Consent

Anti -D is a blood product, informed consent must be obtained from the patient before administration.

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References

FOAMed

• Hillier J. BHCG, Rhesus D and Progesterone. FFS

Publications

• Qureshi H, Massey E, Kirwan D, Davies T, Robson S, White J, Jones J, Allard S; British Society for Haematology. BCSH guideline for the use of anti-D immunoglobulin for the prevention of haemolytic disease of the fetus and newborn. Transfus Med. 2014 Feb;24(1):8-20. doi: 10.1111/tme.12091
• King Edward Memorial Hospital. Pregnancy care: First trimester complications. Sep 2017.