Prevention of Maternal Rh D Alloimmunization: A Comparative Review of Guidelines.

Importance: Rhesus alloimmunization refers to the sensitization of an Rh D-negative mother after exposure to D-positive fetal red blood cells, which can lead to significant fetal and neonatal morbidity and mortality.

Objective: The aim of this study was to review and compare the most recently published international guidelines on the prevention of maternal alloimmunization.

Evidence Acquisition: A comparative review of guidelines from the American College of Obstetricians and Gynecologists, the British Committee for Standards in Hematology, the International Federation of Gynecology and Obstetrics, the Royal Australian and New Zealand College of Obstetricians and Gynecologists, and the Society of Obstetricians and Gynecologists of Canada regarding the prevention of maternal Rh D alloimmunization was conducted.

Results: There is consensus among the reviewed guidelines regarding the timing of antenatal antibody screening; the management of an already sensitized pregnancy; the administration and timing of postnatal prophylaxis with a D-positive neonate; and the need for prophylaxis after invasive procedures, abdominal trauma, and external cephalic version. Controversies exist regarding the management of women expressing weak D blood type and the optimal dose and regimen for routine antenatal prophylaxis, with recommendations suggesting administration between 28 and 34 weeks, versus specifically at 28 weeks. Moreover, significant discrepancies exist regarding the need for prophylaxis after some sensitizing events such as threatened, spontaneous, or surgical miscarriage; termination of pregnancy; and molar and ectopic pregnancy, as well as the optimal dose of anti-D globulin after invasive antenatal procedures, abdominal trauma, external cephalic version, and postnatal prophylaxis.

Conclusions: Anti-D globulin remains an important tool for the prevention of maternal alloimmunization, thus contributing to a significant improvement in fetal and neonatal outcomes. However, due to lack of evidence, discrepancies exist between relevant guidelines. Hence, further studies and the development of consistent evidence-based protocols and algorithms are pivotal to safely guide through pregnancy and subsequently reduce fetal and neonatal morbidity, without subjecting women to unnecessary treatment.