Updated 22 May 2015

Ovarian cysts

Ovarian cysts are fluid-filled, sac-like structures caused by numerous factors.



  • Ovarian cysts are fluid-filled, sac-like structures.
  • Ovarian cysts are caused by numerous factors.
  • When a cyst causes symptoms, pain in the abdomen or pelvis is by far the most common one.
  • Most cysts are diagnosed by ultrasound.
  • The treatment of ovarian cysts varies from observation to surgery.


Ovarian cysts are fluid-filled, sac-like structures within an ovary. The term cyst refers to any fluid-filled structure. Therefore, all ovarian cysts contain at least some fluid.


Regarding the anatomy of the internal reproductive organs, it needs to be understood that the ovary as such is a cystic structure. In a woman of reproductive age, every month a small cyst, called follicle, is produced. A follicle is the normal fluid-filled sac that contains an egg, to be released during ovulation about 14 days before the next anticipated menstrual period.

Ovarian cysts form for numerous reasons. The most common one is a follicular cyst, developing from the growth of such a follicle, which , in some cycles, grows larger than normal and does not open to release the egg. Usually, follicular cysts resolve on their own over the course of days to months.

Cysts can contain blood (haemorrhagic cysts) from injury or leakage of tiny blood vessels into the egg sac. They may contain old blood (chocolate cysts) caused by endometriosis, a condition where tissue of the lining of the womb (endometrium) grows outside the uterus in an ovary. Sometimes, the tissues of the ovary grow abnormally to form other body tissues such as hair or teeth. Cysts with these abnormal tissues are called dermoid cysts.


Most cysts are never noticed and resolve again, without women ever realising the presence of the cysts. When a cyst causes symptoms, pain in the abdomen or pelvis is by far the most common one. The pain can be caused from rupture of the cyst, rapid growth and stretching, bleeding into the cyst, or twisting of the cyst around its blood supply.


Most cysts are diagnosed by ultrasound, which is the best imaging technique for detecting ovarian cysts. Ultrasound is an imaging method that uses high-frequency soundwaves to produce an image of structures within the body. Ultrasound imaging is painless and does not cause any harm.

Cysts can also be detected with other, more expensive imaging methods, such as computerised axial tomography (CAT-scan) and magnetic resonance imaging (MRI scanning).


The ideal treatment of ovarian cysts depends on the woman’s age, the size (and change of size) of the cyst, and the cyst's appearance on ultrasound. Treatment can consist of simple observation, or it can include blood tests such as a CA-125 to help evaluate the cyst for the potential of cancer. (It should be noted that the interpretation of the CA-125 blood test has limitations in that women without cancer may have an elevated blood level, and those with cancer may have a negative blood test.)

If the tumour is causing severe pain, is not resolving or is suspicious in any way, then it can be removed either through laparoscopy, or, if needed, through a laparotomy (abdominal incision). Once the cyst is removed, the tissue is sent to the pathologist for histological examination under a microscope to make the final diagnosis as to the type of the cyst.

For the laparotomy, the mode of incision will depend on the suspicion of possible malignancy. If an ovarian cancer is suspected (usually in elder women), the gynaecological surgeon will not perform a bikini cut but rather a longitudinal incision which can be extended into the upper abdomen to achieve proper access for the removal of any cancer spread.


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