you are seeing a 31-year-old g1p0 woman in the office with increasing lower abdominal pain, mild vaginal bleeding, and fever that started last night. she is two days postop from a suction dilatation and curettage for an incomplete abortion that you performed in your office. on physical examination she has rebound tenderness and lower abdominal guarding. on pelvic exam her uterus is soft and slightly tender. what is the most likely diagnosis?