Guideline for prevention of RhD alloimmunizationin RhD negative women

Overview

Events following which immunoglobulin (Ig) G anti-D should be given to all RhD negative women with no anti-D alloantibodies: First trimester indications (IgG anti-D sufficient dose of 50 μg*) - termination of pregnancy, spontaneous abortion followed by instrumentation, ectopic pregnancy, chorionic villus sampling, partial molar pregnancy; Second and third trimester indications (IgG anti-D sufficient dose of 100 μg*) - amniocentesis, cordocentesis, other invasive prenatal diagnostic or therapeutic procedures, spontaneous or induced abortion, intrauterine fetal death, attempt at external cephalic version of a breech presentation, abdominal trauma, obstetric hemorrhage; Antenatal prophylaxis at 28th weeks of gestation (IgG anti-D sufficient dose of 250 μg*); Delivery of an RhD positive infant** (IgG anti-D sufficient dose of 100 μg*); Minimal dose*: before 20 weeks gestation – 50 μg (250 IU), after 20 weeks gestation*** – 100 μg (500 IU); Timing: as soon as possible, but no later than 72 hours after the event. In cases where prevention of RhD alloimmunization is not performed within 72 hours of a potentially sensitising event, it is still reasonable to administer IgG anti-D within 13 days, and in special cases, administration is still recommended up to a maximum interval of 28 days postpartum; Legend: *administration of a higher dose of IgG anti-D is not a mistake, ** also if the D type is not known, *** simultaneous assessment of the volume of fetomaternal hemorrhage (FMH) to specify the dose is suitable; The FMH volume assessment - If the volume of fetal erythrocytes (red bood cells, RBCs) which entered maternal circulation is assessed, intramuscular administration of IgG anti-D in a dose of 10 μg per 0.5 mL of fetal RBCs or 1 mL of whole fetal blood is indicated. IgG anti-D in a dose of 10 μg administered intramuscularly should cover 0.5 mL of fetal RhD positive RBCs or 1mL of whole fetal blood. FMH is the fetal RBC volume; fetal blood volume is double (expected fetal hematocrit is 50%).

Keywords:
RhD negative women –RhD alloimmunization – prevention – immunoglobulin G anti-D