Anti-D Immunoglobulin Prophylaxis Guidelines and Recommendations
Anti-D immunoglobulin should be administered to all RhD-negative non-sensitized women after potentially sensitizing events to prevent RhD alloimmunization and reduce the risk of hemolytic disease of the fetus and newborn in subsequent pregnancies. 1
Indications for Anti-D Prophylaxis
Postpartum Administration
- Standard dose: 300 μg IM or IV within 72 hours of delivery to RhD-negative women delivering an RhD-positive infant 2
- If administration is delayed beyond 72 hours, anti-D should still be given up to 28 days after delivery, though efficacy may be reduced 2
- Additional anti-D may be required for fetomaternal hemorrhage (FMH) greater than 15 mL of fetal red blood cells 2
Antepartum Routine Prophylaxis
- 300 μg at 28 weeks' gestation when fetal blood type is unknown or known to be RhD-positive 1, 2
- Alternative regimen: two doses of 100-120 μg, one at 28 weeks and one at 34 weeks 2
Early Pregnancy Events (Before 12 Weeks)
- Minimum dose: 50-120 μg for:
Later Pregnancy Events (After 12 Weeks)
- Standard dose: 300 μg for:
Special Considerations
Fetomaternal Hemorrhage (FMH) Assessment
- Quantitative testing for FMH should be considered following events potentially associated with placental trauma 2
- If FMH exceeds the amount covered by standard dosing, additional anti-D should be given at 10 μg per 0.5 mL of fetal red blood cells 2, 3
Threatened Abortion
- Anti-D administration may be unnecessary with threatened abortion and viable fetus before 12 weeks' gestation 4
- However, anti-D should be considered when there is "heavy" bleeding, associated abdominal pain, or when the event occurs near 12 weeks' gestation 4
Minor Abdominal Trauma
- Consider anti-D administration in cases of minor trauma in RhD-negative pregnant patients 4
- 28% of pregnant patients with minor trauma had fetomaternal hemorrhage in one study 4
Ectopic Pregnancy
- Anti-D should be given to RhD-negative women following ectopic pregnancy 2
- Failure to administer anti-D after ectopic pregnancy has been associated with high anti-Rh titers in subsequent pregnancies and delivery of nonviable hydropic fetuses 4
Platelet Transfusions
- Prevention of RhD alloimmunization should be considered for RhD-negative patients receiving platelet transfusions from RhD-positive donors 4, 1
- Priority should be given to RhD-negative children (particularly girls) and women of childbearing age 4, 1
Administration Guidelines
Route and Timing
- Anti-D should be administered intravenously (IV) when possible, especially in thrombocytopenic patients 1
- Should be given before or immediately after exposure to RhD-positive blood, though remains effective if given within 72 hours 1
Dosage Calculation
Potential Adverse Reactions
- Although generally considered safe, anti-D administration carries a small risk of hypersensitivity reactions including anaphylaxis 5, 6
- Management of suspected hypersensitivity reactions requires detailed history, cautious interpretation of skin tests, and in some cases, anti-D challenges 6
Areas of Guideline Discrepancy
- Management of women expressing weak D blood type (should not receive anti-D according to some guidelines) 2, 7
- Optimal dose and regimen for routine antenatal prophylaxis (recommendations vary between administration at 28 weeks versus between 28-34 weeks) 7
- Dosing recommendations for specific sensitizing events vary between guidelines 7
Conclusion
Anti-D immunoglobulin prophylaxis has significantly reduced the incidence of RhD alloimmunization and subsequent hemolytic disease of the fetus and newborn. Following established guidelines for appropriate administration after potentially sensitizing events is crucial for preventing maternal sensitization and protecting future pregnancies.