Suitability of preadmission blood samples for pretransfusion testing in elective surgery

North American transfusion guidelines do not stipulate a time limit between drawing the specimen for pretransfusion testing and giving the transfusion to patients who have not received a transfusion or been pregnant in the preceding 3 months. British guidelines suggest that separated plasma and serum can be stored at -30 degrees C for up to 6 months, but they draw attention to the paucity of evidence concerning the use of stored samples. In Australia, transfusion guidelines recommend a maximum of 10 days' validity for pretransfusion specimens, which requires the patient to present for pretransfusion testing within 10 days of admission or to undergo retesting after admission, which in turn necessitates additional time in the hospital before operation. The study was performed to document the safety of using for pretransfusion testing a blood sample collected more than 10 days before surgery.

Samples from 500 patients scheduled for elective surgery who had not been pregnant or received a transfusion in the previous 3 months were separately tested in blood group and antibody screens at an interval from 11 to 335 days before admission and again on admission.

No clinically significant change was detected in the red cell antibody status of the paired samples of any patient.

For patients who have not been transfused or pregnant in the previous 3 months, it is safe to crossmatch blood for transfusion by using a sample collected well in advance of elective surgery and stored at -30 degrees C.