Uncontrolled acute menorrhagia resulting in hemodynamic instability in the adolescent is uncommon. We report a case of life-threatening menorrhagia upon first menses in a 12-year-old girl who was successfully treated with uterine artery embolization after failure of standard gynecologic and medical measures. Testing eventually revealed a coagulopathy that resulted from decreased plasminogen activator inhibitor-1 activity in combination with an immature hypothalamic-pituitary-ovarian axis. Coagulation disorders are more common in patients presenting with severe menorrhagia upon menarche. Interventional radiologists should be aware of such coagulation abnormalities and the differences between adults and adolescents when contemplating uterine artery embolization for adolescent patients.