Postpartum Management for Rh Negative Mothers
All Rh-negative mothers must receive RhD immune globulin (RhIg) within 72 hours after delivery of an Rh-positive infant to prevent devastating hemolytic disease in future pregnancies. 1, 2
Immediate Postpartum Protocol
Step 1: Confirm Infant's Blood Type
- Determine the newborn's Rh status immediately after delivery 2
- If the infant is Rh-positive or blood type cannot be determined, proceed with RhIg administration 2
- If paternity is certain and the father is confirmed Rh-negative, RhIg is not needed 3
Step 2: Verify Mother's Eligibility
Before administering RhIg, confirm: 2
- Mother is Rh-negative
- Mother is not already sensitized (no anti-D antibodies present)
- Infant has a negative direct antiglobulin test (DAT)
Step 3: Administer Standard Dose Within 72 Hours
Give 300 μg (1,500 IU) of RhIg intramuscularly or intravenously within 72 hours of delivery. 1, 3 This single postpartum dose reduces alloimmunization from 12-13% down to 1-2%. 1, 2 When combined with the antenatal dose given at 28 weeks, protection increases further to 99.8-99.9% (reducing alloimmunization to 0.1-0.2%). 1
Critical Timing Considerations
The 72-hour window is optimal but not absolute: 4, 5
- Administer as soon as possible after delivery for maximum effectiveness 3, 6
- If the 72-hour window is missed, still give RhIg up to 28 days postpartum—delayed administration provides some protection and is far better than no administration 1, 3
- Between 72 hours and 13 days is reasonable; up to 28 days is still recommended in special circumstances 6, 7
Screening for Excessive Fetomaternal Hemorrhage
When to Test for Large FMH
Consider quantitative testing for fetomaternal hemorrhage in these high-risk scenarios: 3
- Placental abruption
- Blunt abdominal trauma during pregnancy
- Placenta previa with significant bleeding
- Manual removal of placenta
- Stillbirth
Four-Step Testing Protocol (U.S. Standard)
Step 1: Perform rosette screen to detect excessive FMH (>30 mL fetal whole blood) 8
Step 2: If rosette screen is negative, give standard single dose of 300 μg RhIg 8
Step 3: If rosette screen is positive, perform quantitative testing (Kleihauer-Betke acid-elution assay or flow cytometry) 8
Step 4: Calculate additional RhIg needed: 3, 6
- Standard 300 μg dose covers up to 15 mL of fetal red blood cells (30 mL fetal whole blood)
- For excess FMH, give additional 10 μg RhIg per 0.5 mL of fetal RBCs beyond the amount covered 3, 6
- The formula includes a precautionary extra vial in borderline situations to prevent underdosing 8
Important Note on Antenatal Dosing
If the mother received antenatal RhIg at 28 weeks, she still requires the full postpartum dose if she delivers an Rh-positive infant. 2 The antenatal dose does not eliminate the need for postpartum prophylaxis—both doses are essential for optimal protection. 1
Common Pitfalls to Avoid
- Don't skip postpartum RhIg if antenatal dose was given—both doses are required for the two-dose protocol that achieves 99.8% protection 1
- Don't assume ABO incompatibility provides protection—while ABO incompatibility offers some natural protection, RhIg should still be administered 9
- Don't withhold RhIg if infant's blood type is unknown—treat as Rh-positive and administer prophylaxis 2, 6
- Don't give RhIg to mothers with "weak D" (Du-positive)—these women are considered Rh-positive and don't need prophylaxis 3
- Don't forget to obtain informed consent—RhIg is a blood product requiring verbal or written consent before administration 3
Documentation Requirements
Document the following in the medical record: 3
- Mother's Rh-negative status and antibody screen results
- Infant's Rh-positive status (or unknown status)
- Time and date of RhIg administration
- Dose administered (including any additional doses for excessive FMH)
- Informed consent obtained