A 32-year-old woman is evaluated during a routine examination. Her medical history is significant for heavy menses, which she has had since her early 20s. Her periods last from 7 to 10 days, with a very heavy flow. She also has epistaxis approximately once per month, which has once required packing. She has been examined by her gynecologist on several occasions for her menorrhagia, but no obvious gynecologic cause for her condition was determined. Her mother and one of her three sisters have also had heavy menses.
Physical examination, including vital signs, is normal. Laboratory studies include a prothrombin time of 12 s, and an activated partial thromboplastin time of 39 s. The complete blood count indicates a hemoglobin of 10.3 g/dL (103 g/L), leukocyte count of 5400/µL (5.4 × 109/L), mean corpuscular volume of 72 fL, and platelet count of 500,000/µL (500 × 109/L).
Which of the following is the most likely cause of this patient's menorrhagia?
A. Essential thrombocytosis
B. Hemophilia A
C. von Willebrand's disease
D. Factor XII deficiency
Answer: C. von Willebrand's disease. The complete MKSAP critique on this topic is available to subscribers as item 33 in the Hematology/Oncology book.