Q. A 35-year-old woman presents to the primary care clinic complaining of heavy menstrual bleeding and pelvic pain that has been worsening over the past 6 months. She reports that her menstrual cycles are regular, but the flow is much heavier than it used to be, often leading to the use of multiple sanitary products at once. She denies any recent changes in weight, appetite, or stress levels. The patient has a medical history of type 2 diabetes mellitus and is currently taking metformin. She has had two uncomplicated vaginal deliveries and no history of sexually transmitted infections. On physical examination, her blood pressure is 125/78 mmHg, heart rate is 78 beats per minute, and temperature is 37.0°C (98.6°F). Abdominal examination reveals an enlarged, boggy uterus and mild, diffuse tenderness to palpation in the lower abdomen. No adnexal masses are palpated, and the remainder of the examination is unremarkable. What is the most appropriate initial diagnostic test to order for this patient?