A 32-Year-Old Woman, Gravida 2 Para 1, Has a Spontaneous

A 32-year-old woman, gravida 2 para 1, has a spontaneous vaginal delivery. Immediately after delivery of the placenta, the patient has a large amount of vaginal bleeding with passage of fist-sized clots, findings consistent with postpartum hemorrhage. A dose of tranexamic acid is administered. Which of the following is the most likely mechanism of action of this drug?

A) Increases vitamin K-dependent coagulation factor levels
B) Induces prostaglandin-mediated smooth muscle contraction
C) Inhibits plasminogen cleavage and prevents fibrin degradation
D) Promotes endothelial release of von Willebrand factor
E) Raises intracellular calcium levels in the uterine myometrium