Do preoperative laboratory tests predict blood transfusion needs in cardiac operations?

We retrospectively compared preoperative prothrombin (PT), partial thromboplastin (PTT), dilute whole blood clot lysis and bleeding times, fibrinogen level, and platelet count with subsequent blood component administration in 92 patients who had undergone cardiac operations with cardiopulmonary bypass (CPB). Abnormal results for one or more tests were found in 34% of 71 adults and 81% of 21 children and teenagers. The patients with abnormal test(s) received no more whole blood and packed red cell units, platelets, or plasma than those with normal tests in either age group. No individual or multiple test abnormalities predicted excess blood component transfusion, even when low-grade abnormalities were excluded. The high rate of abnormal tests in patients less than 20 years of age was not due to polycythemia and may indicate a need for age-specific reference ranges. Baseline PT, PTT, and platelet count may aid in the evaluation of the potential for subsequent development of coagulopathy, but we conclude that further preoperative testing may be reserved for infants, polycythemic individuals, or others in whom history or drug use suggests potential bleeding problems.