Your patient is a 42-year-old woman who is alert and upset, complaining of vaginal bleeding. She states that the bleeding began ten hours ago and is heavier than her normal menstrual flow. Her last menstrual period was three months ago, G3P3, and there is no other significant gynecologic history. Which of the following is the most likely cause of her signs and symptoms?

A) Ectopic pregnancy
B) Pelvic inflammatory disease
C) Menopause-related dysfunctional uterine bleeding
D) Spontaneous abortion

D