Suppression of primary Rh-immunization by anti-Rh

Rh immune globulin immunoprophylaxis after RhD-positive red cell exposure in RhD-negative patients via transfusion: A survey of practices

BACKGROUND

Current Association for the Advancement of Blood & Biotherapies (AABB) standards require transfusion services to have a policy on Rh immune globulin (RhIG) immunoprophylaxis for when RhD-negative patients are exposed to RhD-positive red cells. This is a survey of AABB-accredited transfusion services in the United States (US) regarding institutional policies and practices on RhIG immunoprophylaxis after RhD-negative patients receive RhD-positive (i.e., RhD-incompatible) packed red blood cell (pRBC) and platelet transfusions.

RESULTS

Approximately half of the respondents (50.4%, 116/230) have policies on RhIG administration after RhD-incompatible pRBC and platelet transfusions, while others had policies for only pRBC (13.5%, 31/230) or only platelet (17.8%, 41/230) transfusions, but not both. In contrast, 18.3% (42/230) report that their institution has no written policies on RhIG immunoprophylaxis after RhD-incompatible transfusions. Most institutions (70.2%, 99/141) do not have policies addressing safety parameters to mitigate the risk of hemolysis associated with the high dose of RhIG required to prevent RhD alloimmunization after RhD-incompatible pRBC transfusions.

DISCUSSION

With approximately half of US AABB-accredited institutions report having policies on RhIG immunoprophylaxis after both RhD-incompatible pRBC and platelet transfusions, some institutions may not be in compliance with AABB standards. Further, most with policies on RhIG immunoprophylaxis after RhD-incompatible pRBC transfusion do not have written safeguards to mitigate the risk of hemolysis associated with the high dose of RhIG required.

CONCLUSION

This survey underscores the diverse and inadequate institutional policies on RhIG immunoprophylaxis after RhD exposure in Rh-negative patients via transfusion. This observation identifies an opportunity to improve transfusion safety.

Massive feto-maternal haemorrhage: effect of passively administered anti-D in the prevention of Rh sensitization and haemolytic disease of the newborn

Fourteen mothers carrying ABO compatible but Rh D incompatible pregnancies experienced large feto-maternal haemorrhages (estimated 188 ml, range 50-400 ml red cells). These were all treated with infusions of fresh frozen plasma containing anti-D at a mean immunoglobulin to fetal cell ratio of 129 i.u. (25.8 micrograms)/ml of fetal cells. At 48 h after the infusion 95% of fetal cells had been removed but 3 to 4 days were required for complete removal. The passively administered anti-D was detectable for up to 6-9 months but not after that time. Four of the 14 women had successful pregnancies subsequently although in two of these anti-C + D was present. Of these, one resulted in a clinically affected baby who survived exchange transfusion.

Immunoprophylactic anti-Rho(D) treatment after mismatched transfusions

80 cases of anti-Rho(D) treatment after mismatched transfusions are reviewed to compare the intramuscular (i.m.) and intravenous (i.v.) route of treatment. No severe reactions such as renal failure occurred with either method of anti-D treatment. If the Rh-immune globulin is injected i.m., 20 micrograms anti-D per ml red cells are used. For i.v. anti-D administration, 10-12 micrograms anti-D are suggested. The i.v. method of anti-D treatment is recommended for the future. Furthermore, a scheme of treatment for after mismatched transfusions is described.

The transfusion of Rh-positive blood into Rh-negative women

The incidence of occurrence of transfusion of Rh-positive blood into Rh-negative individuals is unknown at the present time. A survey was designed to ascertain this information for the 12 month period ending March 31, 1974. Replies were obtained from 2,286 transfusion facilities in the United States. A total of 203 patients were reported to have received Rh-incompatible transfusions during the interval studied. Of these, 44 were women 49 years of age or under. Slightly more than half the women who received Rh-positive blood were treated with Rho (D) immune globulin. Those who received an adequate dose did not develop antibodies when appropriately tested. Twenty-five per cent of those who received an inadequate dose of Rh-immune globulin developed antibodies. Forty-two per cent of those receiving no Rh-immune globulin prophylaxis were noted to have antibodies.

Effectiveness of prophylactic Rh immunosuppression after transfusion with D-positive blood

In a published investigation 42 D-negative men were transfused with single units of D-positive R1r (CDe/cde) blood to mimic the D-incompatible transfusion accidents occasionally seen in young D-negative women. Twenty-two men received no therapy and 20 were treated with Rh immunoglobulin in a calculated dose of 20 mug of anti-Rh per milliliter of infused red cells. The reported incidence of serologic D alloimmunization was 81.8 per cent in control and zero per cent in treated recipients. Posttransfusion 51Cr clearance studies with a challenge with the use of 5 ml. of D-positive cells from the same donor at five months in these identical subjects vary from the results based upon the presence of circulating anti-D active antibody. Exponential immune clearance curves occurred in two control and nine treated recipients. As the first evidence of D alloimmunization is an immune Cr clearance curve followed at some later time by circulating active anti-D antibodies, these data could suggest that Rh immunization actually was 90.9 per cent in untreated control subjects and 45 per cent in treated men. The dose of passive Rh immunoglobulin effective in prophylaxis of transfusion Rh immunization of a D-negative person is still not definitely established, but apparently it is greater than 20 mug of anti-Rh per milliliter of D-positive erythrocytes received.