Ovarian cysts are sacs filled with liquid or semi-liquid material that form in the ovaries. The majority are benign and not cancerous. There are several types of ovarian cysts including functional cysts (follicular, corpus luteum, and theca lutein cysts), polycystic ovarian syndrome (PCOS), and endometriomas. Ovarian cysts may cause lower abdominal pain, bloating, or pressure. Ultrasound is used to examine the ovaries and diagnose cysts. Simple cysts under 5-10cm often don't require treatment, while larger or complex cysts may need to be surgically removed. The prognosis for benign ovarian cysts is generally excellent