Simple Ovarian Cysts
A simple ovarian cyst is a common, benign, fluid-filled sac that forms on or within an ovary. These cysts have thin, smooth walls and contain clear fluid. They often occur as part of the normal menstrual cycle and usually resolve on their own. Most simple ovarian cysts cause no symptoms and are found incidentally during imaging.
What is it?
A simple ovarian cyst is a fluid-filled sac that forms during the normal process of ovulation. These cysts can include follicular cysts, which form when a follicle does not release an egg, and corpus luteum cysts, which may form after ovulation. Simple cysts have a characteristic appearance on imaging—thin walls and clear fluid—making them easy to distinguish from more complex or concerning cysts.
Ultrasound is the primary imaging tool used to diagnose simple ovarian cysts. It helps assess the size, appearance, and whether any features suggest a more complex lesion. MRI may be used when ultrasound findings are unclear or when additional detail is needed.
Important to Know
Most simple ovarian cysts resolve naturally within a few menstrual cycles. They are almost always benign and rarely require treatment. Larger cysts may cause mild discomfort or pressure, and in rare cases, a simple cyst can rupture, causing sudden pain.
Red flag symptoms include sudden severe pelvic pain, fever, vomiting, fainting, or heavy bleeding, which may indicate cyst rupture or ovarian torsion. Persistent pain or cysts that do not resolve may require follow-up imaging or evaluation.