When should RhoGAM (Rho(D) immune globulin) be administered to Rh-negative pregnant women?

Administration of RhoGAM (Rh Immune Globulin) for Rh-Negative Pregnant Women

Rh immune globulin should be administered to unsensitized Rh-negative women after delivery of an Rh-positive infant, following spontaneous or induced abortion regardless of gestational age, and at 28 weeks' gestation in ongoing pregnancies. 1

Indications for RhoGAM Administration

Postpartum Administration

• Administer within 72 hours of delivery to all unsensitized Rh-negative women who deliver an Rh-positive infant 2
• If not given within 72 hours, should still be administered up to 28 days after delivery, though efficacy may be reduced 3
• Dose: 300 micrograms IM or IV 3
• Additional doses may be required if fetomaternal hemorrhage exceeds 15 mL of fetal red blood cells 3

Antepartum Administration

• Routine prophylaxis at 28 weeks' gestation for all unsensitized Rh-negative pregnant women when fetal blood type is unknown or known to be Rh-positive 1, 3
• Dose: 300 micrograms IM or IV 3
• Alternative regimen: Two doses of 120 micrograms - one at 28 weeks and one at 34 weeks 3

Abortion/Pregnancy Loss

• For spontaneous or induced abortion before 12 weeks' gestation:
  • 50 mg (microdose) within 72 hours is adequate 1
  • If 50 mg dose unavailable, use 300 mg dose 1
• For abortion/pregnancy loss after 12 weeks' gestation:
  • 300 micrograms within 72 hours 3

Other Indications

• Following potentially sensitizing events:
  • Amniocentesis: 300 micrograms 3
  • Chorionic villus sampling: 120 micrograms if <12 weeks, 300 micrograms if >12 weeks 3
  • Ectopic pregnancy: 120 micrograms if <12 weeks, 300 micrograms if >12 weeks 3
  • Abdominal trauma, placental abruption, or other events with potential fetomaternal hemorrhage 3

Important Considerations

Prioritization During Shortages

When RhoGAM supplies are limited, prioritize:

1. Postpartum patients
2. Antenatal patients at later gestational ages 1

Testing Requirements

• All pregnant women should be typed and screened for alloantibodies at first prenatal visit and again at 28 weeks 3
• When paternity is certain, testing the baby's father may eliminate unnecessary administration 3
• Women with "weak D" (Du-positive) should not receive RhoGAM 3

Special Circumstances

• In abortion care settings where RhD testing and RhoGAM administration would limit access to abortion care, the priority should be to complete the abortion 1
• Patients should be counseled on the implications of unknown blood type and potential risks of not receiving RhoGAM 1

Route of Administration

• Both IM and IV routes appear equally effective 4
• Choice depends on available preparations, dose, and patient preferences 4

Potential Pitfalls and Caveats

• Failure to administer RhoGAM within 72 hours significantly reduces effectiveness
• Underestimating fetomaternal hemorrhage can lead to insufficient dosing
• Omitting RhoGAM after early pregnancy loss (<12 weeks) can still lead to sensitization
• Assuming that first-trimester pregnancy loss carries no risk of sensitization is incorrect - the Society for Maternal-Fetal Medicine recommends RhoGAM even for losses <12 weeks 1
• Failure to recognize that RhoGAM is a human blood product requiring informed consent 3

RhoGAM has significantly reduced the burden of hemolytic disease of the fetus and newborn, with rates of D-antigen sensitization reduced to 0-2.2% with proper administration 5. Following these guidelines ensures optimal protection against Rh alloimmunization and its potentially devastating consequences.