Do we give Rhogam (Rho(D) immune globulin) for miscarriage in Rh-negative women?

Administration of RhIg for Miscarriage

Rh-negative women who experience a miscarriage should receive RhD immune globulin (RhIg) to prevent Rh alloimmunization and its associated adverse outcomes in future pregnancies. 1, 2

Rationale and Evidence

• The Society for Maternal-Fetal Medicine (SMFM) recommends offering both RhD testing and RhIg administration for spontaneous and induced abortion at <12 weeks gestation in unsensitized Rh-negative individuals 1
• Fetal red blood cells display RhD antigens from as early as 6 weeks of gestation, making maternal sensitization possible even in early pregnancy 2
• RhD alloimmunization can lead to serious fetal and neonatal outcomes including hemolytic disease of the fetus/newborn, need for fetal transfusion, fetal hydrops, stillbirth, and preterm delivery 1, 2
• The FDA-approved drug label for RhIg explicitly states it "should be administered within 72 hours to all nonimmunized Rho(D) negative women who have undergone spontaneous or induced abortion" 3

Dosing Guidelines

• For miscarriage before 12 weeks gestation, a dose of 50 μg RhIg within 72 hours is adequate 1, 2
• If the 50 μg dose is unavailable, the standard 300 μg dose should be used 1, 2
• RhIg should be administered within 72 hours of the miscarriage, but can still provide some benefit if given up to 28 days after the event 4

Special Considerations

• While some guidelines (Society of Family Planning, WHO) have suggested against routine RhIg for abortions <12 weeks, SMFM notes that available data "do not convincingly demonstrate the safety of forgoing RhIg" 1
• The mechanism of action involves suppressing the maternal immune response to fetal RhD-positive red blood cells, preventing sensitization that could affect future pregnancies 3
• If RhIg supply is limited, postpartum patients and antenatal patients at later gestational ages should be prioritized 2

Clinical Algorithm

1. Determine Rh status: Test all women experiencing miscarriage for Rh status if not already known 2
2. For Rh-negative women:
   • Administer 50 μg RhIg within 72 hours of miscarriage if <12 weeks gestation 1, 2
   • Use 300 μg dose if 50 μg is unavailable 1, 2
   • Consider 300 μg dose if miscarriage occurs near 12 weeks or is accompanied by heavy bleeding or abdominal pain 1, 5
3. Documentation: Document administration of RhIg in the medical record 4

Potential Pitfalls

• Failure to check Rh status: Studies show that Rh status is often not checked in emergency settings, leading to missed opportunities for prophylaxis 5
• Assuming early miscarriages don't require RhIg: Despite limited evidence of sensitization in very early pregnancy, fetal RBCs display RhD antigens from 6 weeks gestation 2
• Delaying administration: While most effective within 72 hours, RhIg should still be given if the need is recognized later (up to 28 days after the event) 4
• Not considering paternity: If paternity is certain and the father is known to be Rh-negative, RhIg is not necessary 3, 4

While the Cochrane review noted insufficient data to definitively evaluate this practice 6, the most recent guidelines from SMFM (2024) and the FDA drug label clearly support RhIg administration after miscarriage in Rh-negative women 1, 3.