What is the primary action of aspirin related to postoperative bleeding?

The primary action of aspirin that is most relevant to postoperative bleeding is its inhibition of platelet aggregation. Aspirin works by irreversibly inhibiting the enzyme cyclooxygenase (COX), which is crucial for the synthesis of thromboxane A2 in platelets. Thromboxane A2 is a compound that promotes platelet aggregation and vasoconstriction, both of which are important for normal hemostasis.

By inhibiting the production of thromboxane A2, aspirin effectively reduces the ability of platelets to clump together. This antiplatelet effect is particularly significant in the context of surgery or any procedure where bleeding is a concern, as the formation of a stable platelet plug is necessary to prevent excessive blood loss.

Thus, the action of aspirin directly leads to an increased risk of postoperative bleeding due to impaired clot formation, making the inhibition of platelet aggregation a critical factor in understanding its impact on hemostasis in the postoperative setting.