A 34-year-old woman presents to the emergency department with a sudden onset of dizziness and lower abdominal pain, specifically on the right side, which started 12 hours prior to her visit. The pain has progressively worsened, radiating to her shoulder, and is accompanied by light vaginal bleeding. She notes that her last menstrual period was 7 weeks before this episode. Her medical history included a treated case of pelvic inflammatory disease, a prior tubal surgery, a prior ectopic pregnancy, and prior IUD use. She smokes more than 20 cigarettes per day and drinks 2 or 3 alcoholic beverages. Upon examination, her vital signs showed a blood pressure of 90/60 mmHg, a heart rate of 104 bpm, respiratory rate of 18 breaths per minute, and a temperature of 37.2°C. The abdominal examination reveals tenderness in the right lower quadrant with rebound tenderness and guarding. A pelvic exam confirms right adnexal tenderness with minimal blood in the vaginal vault. In this visit, which of the following is the most significant risk factor for ectopic pregnancy in this patient?
