Red blood cell isoimmunisation describes the production of antibodies in response to an isoantigen present on an erythrocyte

Overview

• The D antigen is found on red blood cells and is an important antigen in the rhesus factor system
• Rhesus isoimmunisation can occur when a rhesus negative mother has a baby which is rhesus positive
• If any foetal red blood cells enter the maternal circulation, the mother will form anti-D antibodies against them
• The maternal anti-D antibodies can cross the placenta in subsequent pregnancies and cause Rhesus haemolytic disease if the future baby is rhesus positive

Management

• Women that are rhesus-D positive do not need any additional treatment during pregnancy
• When a woman that is rhesus-D negative becomes pregnant, we have to consider the possibility that her child will be rhesus positive
• If a sensitising event occurs, maternal isoimmunisation can be prevented via the administration of anti-D immunoglobulin
  • It binds to any RhD+ cells in the maternal circulation, and no immune response is stimulated
  • Examples of sensitising events include: invasive obstetric testing, ectopic pregnancy, fall or abdominal trauma, intrauterine death, miscarriage, termination of pregnancy, delivery
  • Only required if mother is RhD-
• Anti-D is also given to all non-sensitised Rhesus negative mothers at 28 weeks