Review Question - QID 203353

A 25-year-old woman comes into your office with complaints of heavy bleeding. She states that her mother also has heavy bleeding during her menstrual cycle. She has had a heavy flow as long as she can remember and had her first menstrual cycle at age 12. She states during her cycle, she has to change pads every 2 hours for at least 3 days. She also states that she gets bruised easily just like her mother. She denies any past medical history other than her heavy menstrual flow and denies taking any medications. She also denies any medical history in her father and says he is "perfectly healthy." Her vitals are HR 85, T 98.8 F, RR 13, BP 125/75. Her CBC is significant for Hgb 10.5, WBC 5.8, Plts 250, Hct 33. On coagulation studies, her PT is 14 seconds and her PTT is 43 seconds. Her INR is 1.1. What is the most likely cause of this patient's menorrhagia?