The appearance is of an ovarian hemorrhagic cyst.

Small hemorrhagic cysts (<5 cm) with a typical sonographic appearance do not require routine followup - although in practice, a repeat ultrasound is often performed regardless, to alleviate clinician or patient anxiety.

In this case, the cyst measured just under 5 cm and was followed up 3 months later at which time it had resolved, confirming its benign and transient nature.