Transfusion of Rh positive platelets to Rh negative neonates

A colleague comments that at her facility the local policy is to transfuse Rh negative neonates who need platelet transfusions with aliquots from Rh negative apheresis platelets. These aliquots are leukocyte-reduced, CMV negative, and irradiated. The inquiring colleague would like to know what other facilities do if Rh negative platelets are unavailable for Rh negative neonates. Do any facilities issue Rh positive platelets to their Rh negative neonates followed by the administration of Rh Immune Globulin (RHIG)? If so, is the RHIG administered intravenously, to avoid hematoma formation?

The following comments has been received.

1. Dr. Breanndan Moore of the Mayo Clinic (attribution used with permission) makes reference to a study published by Molnar and colleagues in Transfusion (2002; 42:177-182). In this study Molnar et al looked at an estimated 2300 D incompatible platelet transfusions to pediatric Hematology/Oncology patients over 3.5 years. None of them were given prophylactic RHIG. All the patients were given single donor apheresis platelets and none of them developed anti-D. Dr. Moore points out that the Molnar patients’ medical conditions would have diminished the likelihood of antibody response (as previously demonstrated years ago by Goldfinger and McGinnis in an article in the New England Journal of Medicine 1971;234: 942-944). However, most people would agree that neonates are quite unlikely to form new antibodies in response to transfusions and so might be considered to be equivalent to Heme/Onc patients in that particular respect. Based on the Molnar paper, Dr. Moore reports that he would be comfortable transfusing single donor apheresis Rh(D) positive platelets to an Rh(D) negative neonate without resorting to the use of Rh immune globulin. However, if the clinician or parents insisted on its use, he would use the intravenous route (provided that the RHIG has been cleared by FDA for use in neonates!) In the absence of such clearance he would advise against using the RHIG intramuscularly on the basis that the risk of hematoma formation probably exceeds the risk of formation of anti-D.

ADDENDA Apr. 8, 2004

2. Editor's Note: A related discussion on this subject has been posted earlier on this forum, and merits review.

ADDENDA Aug. 18, 2004

3. The Editor wishes to draw attention to a case report by Haspel RL et al in the May 2004 issue of Transfusion, entitled "Platelet transfusion in an infant leading to formation of anti-D: implications for immunoprophylaxis". An Rh(D) negative infant undergoing surgery for congenital heart disease developed anti-D after receiving 2 platelet concentrates from Rh positive donors during an earlier operation at 17 weeks of age. Based on this observation the authors recommend RHIG to all Rh negative pediatric patients (regardless of age or gender) receiving platelets from Rh positive donors.
   
   Comments about this recommendation are encouraged.

ADDENDA May 19, 2004

4. A colleague from Rochester, New York reports that in his experience, infants less than 3-4 months of age almost never make antibodies to allogeneic red cells. In his opinion, the infant described in the recent report in Transfusion is a rare exception. His hospital's policy is to give Rh and ABO identical platelets to infants, particularly female infants. They would certainly give Rh immune globulin to a female infant who had to be exposed to Rh positive platelets. For male infants, they would have to consider each case separately. He adds that the safety of Rh Immune Globulin is pretty good, but do we know for sure it is safer than just doing nothing and accepting a rare Rh sensitization in a male infant? We do not, in his opinion. Therefore he would argue that calls to administer Rh immune globulin to any infant, particularly to males under 4 months of age, are premature and not supported by adequate data.
   
   
5. A colleague from Barcelona, Spain reports that in his opinion, two factors should be taken into account before recommending the administration of RhIg to all D- pediatric patients receiving platelet transfusions from D+ blood donors:
   • the level of immunosuppression of the recipient, and
   • the red blood cell content of the transfused platelet product (higher in whole blood-derived platelets)
   In children, as in adults, D- immunosuppressed recipients who receive transfusions of D+ platelets obtained from automated apheresis collections have a low probability of becoming alloimmunized to D, and immunoprophylaxis could be discouraged. In contrast, D- immunocompetent recipients who receive transfusions of D+ platelets that are manufactured  from manual whole blood collections have a higher probability of becoming alloimmunized to D, and immunoprophylaxis could be encouraged.  Only randomized, well-defined and well-conducted studies will provide the necessary data to clearly define guidelines for this still unresolved aspect of platelet transfusions.

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