A 26-year-old sexually active woman presents with 5 days of worsening bilateral lower abdominal pain, fever (38.9°C), foul purulent vaginal discharge, and cervical motion tenderness. Cervical swabs are positive for Chlamydia trachomatis. Transvaginal ultrasound shows a right adnexal mass measuring 7 cm. The structure marked **A** in the diagram—a multiloculated complex adnexal mass with internal debris and thick irregular walls—is identified. Given these clinical and imaging findings, what is the most appropriate next step in management?