Anti-D immunoglobulin

Overview

Passive immunisation that prevents RhD-negative mothers becoming sensitised to RhD-positive fetal cells — preventing haemolytic disease of the newborn in future pregnancies.

Mechanism

Exogenous anti-D antibody binds and clears fetal RhD-positive red cells from the maternal circulation before the maternal immune system can mount its own anti-D response — preventing maternal alloimmunisation (sensitisation).

Indications

• RhD-negative women: routine antenatal prophylaxis (~28 weeks)
• After any potentially sensitising event in an RhD-negative woman: delivery of RhD+ baby, miscarriage/ectopic, APH, ECV, amniocentesis/CVS, abdominal trauma

Adverse effects

Cautions & contraindications

Interactions

• May impair response to live vaccines (e.g. MMR) — separate timing

Monitoring & kinetics

Kleihauer test after sensitising events / delivery to quantify feto-maternal haemorrhage and guide additional dosing

IM (or IV). Give within 72 hours of the sensitising event.