A blood bank physician in one of the Carolinas reports about a premature female infant who required a platelet transfusion. The patient was B negative, but the transfusion service only had one dose of B negative CMV negative platelets available. After the platelet transfusion, the patient's platelet count remained low. When a second dose of platelets was requested, there were no B negative platelets available. However, all other ABO/Rh combinations (including AB negative) were available. The inquiring blood banker wanted to give Rh compatible platelets to avoid possible alloimmunization to the D antigen in this female child. The inquiring blood banker's question to the e-network is "how important is it to avoid Rh mismatches for Rh negative female neonates? If such a transfusion must be given, should Rh immune globulin be used?"

At least one blood banker advised against the use (if at all possible) of Rh positive platelets for an Rh negative female child, to avoid potential problems with future pregnancies. The responding blood banker observed that since the inquiring blood banker had group AB negative platelets available, the AB negative platelets should be used next, since AB negative platelets would be Rh matched and would not contain anti-B. If the AB negative platelets were not CMV antibody negative, the product could be leukocyte reduced (either in the laboratory or at the bedside) before they were transfused.

Editor's NOTE: As you consider the above discussion the following links to related issues previously discussed on this forum may of interest:

• Who considers leukoreduced cellular blood products equivalent to those made from CMV seronegative donors?
• AABB ASSOCIATION BULLETIN: #99-7 - Leukocyte Reduction
• Washed and volume-reduced Plateletpheresis units
• Single Donor Platelets are associated with fewer Septic Reactions than Platelet Concentrates
• Rh immune globulin (RHIG) administration after transfusion of Rh-pos platelets/plateletpheresis units to Rh-neg recipients
• Usage of Pooled Platelets vs Pheresis Platelets

The following replies were submitted in response to the above question and comments.

There appears to be a consensus to avoid using Rh positive platelets for Rh negative neonates whenever possible, and if it is not possible to avoid such a platelet transfusion, to consider employing an appropriate anti-D immunoprophylaxis strategy. Remember that patients with very low platelet counts are at risk of developing hematoma formation following intramuscular injections, and that only certain preparations of Rh immune globulin are approved for intravenous administration.

1. A blood banker from Catalonia, SPAIN wrote that it is a good practice to administer RHIG for immunocompetent Rh negative girls and Rh negative women of childbearing age who are exposed to Rh positive platelet products. In the case of immunosuppressed patients, however, the answer is not so clear-cut, according to a study reported by Cid, J et al in Transfusion, Feb., 2002. (ADDED 3-12-02)

2. A blood banker from the United Kingdom (UK) wrote that there is insufficient evidence to know for sure whether an Rh positive platelet concentrate would sensitize an Rh negative neonate. However, intuitively we should avoid Rh D exposure as much as possible, as a full term or even premature baby's immune system could recognize the D allo-antigen. The UK blood banker does not like the idea of 'treating' one situation (possible D sensitization) with another (passive human IgG anti-D, which would have to be given either subcutaneously or intravenously - not without extra hazard). So the UK blood banker would favor the suggestion (in the comments above) that group AB, Rh negative platelets, that are CMV seronegative or leukoreduced, be given in this scenario. The recovery of the group AB platelets in the baby should be fine as it is very unlikely that the baby will have much anti-A on board, and the expression of the A antigen on the transfused platelets is unlikely to be very strong. There is unlikely to be a strong reaction between any anti-A in the baby's plasma (the presence of which would depend on the mother's ABO type anyway) and any transfused AB red cells. According to the UK blood banker, the inquiring blood banker's blood bank was lucky to have an AB negative platelet product in stock! The UK blood banker continues saying that the next choice would be (perhaps counterintuitively) to use group A Rh negative platelets; then group O Rh negative. Again, any maternally derived anti-A in baby's plasma is unlikely to cause a major problem by reacting with transfused red cells or platelets; and neither is the anti-B in the plasma of group A platelets likely to react significantly with baby red cells (on which the B antigen will only be poorly expressed) or baby platelets (even lower B antigen expression). Were group O platelets given, the UK blood banker would check for the absence of 'high titer' anti-A,B in their plasma; even though this is not foolproof, again any adverse reaction is likely to be slight.

3. A California blood banker reported that he did a "mini search" into this scenario and everything he read suggested that "we should honor Rh when transfusing platelets into female neonates. Granted, the neonatal (especially the premature neonatal) immune system is not as developed as that of the adult. Still, we know that, soon after birth, infants are beginning to make their own antibodies following immunizing events". Therefore, based on the foregoing, the responding blood banker has always strongly recommended administering a mini-dose of RhIg (i.e., 50 ug) following the transfusion of Rh-positive platelets into Rh-negative female neonates.

4. A former hospital transfusion service graveyard shift bench technologist wrote that he had to make decisions about alternative blood group/type selections with regularity, when ABO/Rh identical platelets were not available. The responding blood banker would select AB negative platelets, as suggested in the comments above, to avoid infusion of ABO incompatible antibodies and Rh mismatched red blood cells (which are often contained in platelet units). The responding blood banker now works at a blood donor center, and comments that he is continually amazed at the number of AB platelets that are returned by hospitals, because the hospitals prefer not to use AB platelets, except for AB patients. He says that these same hospitals are always clamoring for group A or group O platelets instead. This blood banker concludes by saying that when he was working the bench, AB Positive and AB Negative, CMV negative platelets were like liquid gold! He and other techs would have given their eye teeth to always have some available, especially for BMT and neonatal patients.

ADDENDA Feb. 17, 2002

5. A blood bank physician in Texas said that he would definitely give IV WInRho (anti-D) to this neonate if there is no B or AB Rh negative platelets, and Rh positive platelets needed to be used. He adds that the use of IV WInRho (anti-D) is a routine practice at his institution for all Rh negative women of childbearing age who need to be given Rh positive platelet transfusions.

ADDENDA Mar. 13, 2002

6. A blood banker from Leiden, The Netherlands, reports that at his medical center, they have been giving Rh(D) immunoglobulin to Rhesus mismatched platelet recipients for about 25 years, about once every two weeks using a dose of 375 I.U. (75 ug) given by intramuscular injection. He reports that they have never seen Rh(D) sensitization in this period in about 1000 mismatched transfusions. However most recipients are immune suppressed through the conditioning regimes for stem cell transplantations.

7. An East Coast blood banker wanted to remind the e-network that since there are no D antigens on platelets, it would seem prudent to title the topic "platelets from Rh(D)-positive or Rh(D)-negative donors." There are no Rh-positive platelets, only platelet products that might contain contaminating Rh positive red blood cells. In addition, while not focusing directly on neonates, the East Coast Blood Banker suggests that the following article addresses pertinent issues: Ewing CA, Rumsey DH, Langeberg, and Sandler SG: Immunoprophylaxis with intravenous Rh immune globulin should be standard practice when selected D-negative patients are transfused with D-positive random donor platelets. Immunohematology 1998; 14:133-137 (PDF). The article addresses the color of platelet concentrates in terms of the volume of contaminant RBCs, and relates that volume to a sensitizing dose of D-positive RBCs.

ADDENDA Mar. 15, 2002

8. A blood banker from Spain adds that a recent paper about D alloimmunization in pediatric patients receiving D-incompatible single-donor platelets is available in Transfusion 2002;42:177-82 and the editorial of February 2002 issue of TRANSFUSION is an excellent review about the current knowldge about this topic.

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Ira A. Shulman, MD
CBBS e-Network Forum Editor & Moderator