Evidence to support the single-dose over the two-dose protocol for routine antenatal anti-D Rhesus prophylaxis: a prospective observational study.

OBJECTIVE: To assess the potential benefit of the single-dose compared with two-dose protocol for routine antenatal anti-D prophylaxis (RAADP). STUDY DESIGN: Prospective observational study during February to October 2009 in a district teaching hospital delivering 6000 women annually. Obstetric notes of eligible RhD negative women were reviewed following delivery to identify gestation and dose for RAADP injections, with laboratory confirmation when necessary. The primary outcome was compliance administering RAADP at the appropriate gestation with the secondary analysis of compliance for nulliparae and multiparae. RESULTS: For 644 eligible women, there was no statistically significant difference in administering the 28 week injection between the two-dose (95%) and single-dose (98%) protocols (P=0.17, OR 2.47: 95%CI (0.73, 8.34)). Compliance giving the injection at the correct gestation at 28 ± 1 weeks was achieved in 78% and 77% respectively (P=0.72, OR 1.10: 95%CI (0.69, 1.74)). For the two-dose protocol the second injection was given to 96% of those who had received the first injection, but at the correct time point in only 67%. By eliminating the variability of the 34 week injection, the single-dose protocol resulted in significantly greater overall success in giving RAADP at the appropriate times compared with the two-dose protocol (P=0.021, OR 1.68: 95%CI (1.08, 2.64)). There were no differences between nulliparae and multiparae for both protocols. CONCLUSION: The single-dose protocol provides enhanced compliance over the two-dose protocol with the potential for reduced sensitisation combining economic and manpower benefits. There remains room for improvement in administering RAADP at the correct gestation.