Ovarian cyst is a relatively common occurrence and many women at some time in their lives will be diagnosed with an ovarian cyst. An ovarian cyst is a closed sac within the ovary that contains fluid, with or without solid material. Sometimes, cysts are found because a woman is having pain or discomfort, or sometimes, they are discovered on a routine gynaecological examination. The majority of ovarian cysts in pre-menopausal women will be "normal" cysts, related to development of the egg in the ovary and ovulation. These cysts will almost always go away over time. Ovarian cysts that are persistent, symptomatic or suggestive of malignancy should be removed. Depending on the individual's condition, ovarian cysts can be removed using laparoscopy (keyhole surgery) or laparotomy (conventional open operation).
Upon the diagnosis of an ovarian cyst, it is important to determine the likelihood of the cyst to be cancerous. More detailed ultrasound examinations (like Doppler) and blood tests (like ovarian tumour markers) can help to assess the risk of the cysts being cancerous. If the cyst is deemed unlikely to be cancerous, then its size should be monitored over the course of four to six weeks with ultrasound scan. Cysts that get smaller between two different ultrasounds usually require no further treatment. Ovarian cysts that do not get significantly smaller over the course of a month or two are more likely to be tumours. These tumours are generally benign, or non-cancerous, especially in younger women. If the cysts are small (less than 5cm) and do not cause any symptom, they can often just be monitored periodically. If the size of cyst is large (more than 5cm), or if the cyst shows suspicions of being cancerous or if it is difficult to accurately determine exactly what kind of cyst is present, it should be removed surgically.
Ovarian cysts can often be removed via laparoscopy (keyhole surgery using several tiny incisions in the abdomen to do the operation). Sometimes, if the cyst is quite large or if there is a high suspicion of cancer, it is advisable to do the operation through a larger abdominal incision. Often, only the cyst needs to be removed, leaving the rest of the normal ovary in place but sometimes, it is necessary to remove the entire ovary. If an ovary is removed, the other remaining ovary will take over the function for both ovaries, so periods and fertility generally are not affected. After removal, the cyst will be sent for examination under a microscope to determine if the growth is cancerous.
(based on Wikipedia article)