What is the management of Rh (Rhesus) hemolytic disease in an Rh-negative mother with an Rh-positive fetus?

Management of Rh Hemolytic Disease in Rh-Negative Mother with Rh-Positive Fetus

The management of Rh hemolytic disease requires administration of Rh immune globulin (RhoGAM) at 28 weeks' gestation and within 72 hours after delivery to prevent maternal alloimmunization in unsensitized Rh-negative women carrying Rh-positive fetuses. 1, 2

Antenatal Management

Screening and Prevention

• All pregnant women should be typed and screened for blood type and alloantibodies at first prenatal visit and again at 28 weeks 3
• For unsensitized Rh-negative women:
  • Administer 300 mcg of Rh immune globulin at 28 weeks' gestation 1, 2
  • Alternatively, two doses of 120 mcg may be given: one at 28 weeks and another at 34 weeks 3
• If paternity is certain and father is Rh-negative, Rh immune globulin is not necessary 2, 3

Monitoring During Pregnancy

• For already sensitized Rh-negative women (positive antibody screen):
  • Serial monitoring of maternal anti-D antibody levels
  • Serial ultrasound assessments to detect signs of fetal anemia
  • Consider amniocentesis for bilirubin levels if indicated
  • Fetal blood sampling may be necessary to assess severity
  • Intrauterine transfusion for severe fetal anemia 4

Special Circumstances Requiring Rh Immune Globulin

• Amniocentesis: 300 mcg 1, 3
• Chorionic villus sampling: 120 mcg before 12 weeks, 300 mcg after 12 weeks 3
• Cordocentesis: 300 mcg 3
• Abdominal trauma: 300 mcg with testing for fetomaternal hemorrhage 1, 3
• Threatened abortion: 300 mcg, especially with heavy bleeding, abdominal pain, or near 12 weeks' gestation 1
• Ectopic pregnancy: 120 mcg before 12 weeks, 300 mcg after 12 weeks 3
• Molar pregnancy: Administer unless diagnosis of complete mole is certain 3

Postpartum Management

After Delivery

• Within 72 hours of delivery of an Rh-positive infant:
  • Administer 300 mcg of Rh immune globulin to unsensitized Rh-negative mother 1, 2, 3
  • If not given within 72 hours, should still be administered up to 28 days postpartum 3

Assessment of Fetomaternal Hemorrhage

• Screen for excessive fetomaternal hemorrhage (>30 mL fetal whole blood) using rosette test 5
• If positive, quantify using acid-elution (Kleihauer-Betke) assay or flow cytometry 5
• For fetomaternal hemorrhage >15 mL of fetal red blood cells, additional Rh immune globulin is required 3
  • Calculate additional dose: 10 mcg for every additional 0.5 mL fetal red blood cells 3

Management of Affected Neonates

• For neonates with hemolytic disease:
  • Monitor for hyperbilirubinemia and anemia
  • Phototherapy for hyperbilirubinemia
  • Exchange transfusion for severe cases
  • Intravenous immunoglobulin (IVIG) may be considered, though evidence for efficacy is not conclusive 6

Important Caveats

• Only unsensitized Rh-negative women (negative antibody screen) are eligible for Rh immune globulin prophylaxis 1
• Women with "weak D" (Du-positive) should not receive Rh immune globulin 3
• Verbal or written informed consent must be obtained prior to administration 3
• In cases of supply shortages, prioritize postpartum patients and antenatal patients at later gestational ages 1
• Despite availability of prophylaxis for over 50 years, approximately 50% of women worldwide who require immunoprophylaxis do not receive it, leading to continued cases of Rh disease 7

The combination of antenatal and postpartum immunoprophylaxis is approximately 99% effective at preventing maternal sensitization to Rh(D), which has dramatically reduced the incidence of hemolytic disease of the fetus and newborn 7.