An analysis of blood transfusion of surgical patients by sex: a question for the transfusion trigger.

The factor or constellation of factors which precipitates blood transfusion in hospitals can be termed the "transfusion trigger." The blood transfusion experience of 535,031 male and female surgical patients was compared in order to evaluate the importance of the hematocrit as a component of this transfusion trigger. Transfusion data presented support the hypothesis that surgeons use the same support and ceiling hematocrit levels to regulate blood transfusion in men and women, despite the fact that women have lower hematocrits. The use of a lower hematocrit support level to govern the blood transfusion of female surgical patients should be considered. Data cited showing that women have a degree of physiologic adaptation to their lower hematocrits suggest that this change could be introduced without causing increased morbidity. A net saving of blood would most certainly result from it.