What’s your diagnosis based on these images from a transvaginal scan of a woman with pelvic pain?

1. Intrauterine pregnancy—anembryonic gestation

The uterine cavity appears empty with evidence of decidual change. The right adnexal region shows a cystic lesion with a nodule within it and surrounded by the typical ring of fire due to vessels within the wall of the lesion. The nodule shows evidence of vascularity, suggesting a live ectopic pregnancy. A small functional cyst of the ovary is also seen.

Challenge your diagnostic skills: Can you identify the cause of this woman’s pelvic pain?