Review Question - QID 214359

A 56-year-old woman presents to her gynecologist for vaginal bleeding for the past 3 days. Her bleeding has not subsided and is not associated with pain. She denies any vaginal or abdominal trauma and reports feeling otherwise well. She underwent menopause at 52 years of age and has not had a menstrual period since. She has a history of hypertension and obesity, for which she is treating with diet and exercise. She is currently not on any medications. Pelvic examination is unremarkable. Her body mass index is 31 kg/m^2. Which of the following is the most appropriate test to confirm the diagnosis?