Ovarian cyst

Cysts are fluid-filled sacs. Ovarian cysts occur on the surface of the ovary (when they may grow as a sort of balloon on a stalk) or within the ovary. Although the great majority of cysts are benign, some can be malignant.

Most women develop some cysts throughout their reproductive years, although they never know about it because cysts are usually silent and produce no symptoms, and are only picked up either accidentally during an ultrasound examination or during a routine pelvic exam.

What causes cysts?

Most cysts are produced as a result of normal hormonal functioning. To release that month's egg, the ovaries produce one or more follicles, or extensions from the ovary through which the egg can pass, and which also serve as a production center for estrogen and progesterone. Normally, follicles regress when the egg is released, but if a normal follicle keeps expanding, it becomes a cyst. This is called a functional follicular cyst.

Another type of functional cyst is a corpus luteum cyst. When the egg is released, if the channel through which it has burst seals off very quickly, the corpus luteum (the hormone production centre) underneath starts to expand into a cyst. Most corpus luteum cysts also regress quickly, but they can sometimes grow into a large size, and then burst or twist, leading to symptoms like sudden, acute pain.

Cysts can also be produced as part of a disease process. For example, endometriosis, pelvic inflammatory disease, ectopic pregnancy, polycystic ovary syndrome, and ovarian cancer can lead to ovarian cysts.

Dermoid cysts form from "leftover" fetal tissue and can contain skin, hair, even teeth.

What symptoms do cysts lead to?

Most cysts are silent and produce no symptoms. When cysts do lead to symptoms, these can include menstrual irregularities from a hormonal effect, pelvic or low back pain that can vary from mild, occasional pain to severe, persistent pain, pain during intercourse, a feeling of fullness or heaviness in the low abdomen or pelvis, and if the cyst is large enough, pressure on other organs like the bladder or bowel.

Occasionally, cysts can twist on their stalks or rupture, leading to sudden severe pain that should be evaluated ASAP.

How can you tell if a cyst is benign or malignant?

When a doctor feels a mass on the ovary, he or she will nearly always order a pelvic ultrasound examination to help define the lump. Ultrasound can help determine if a mass is solid or soft, if it's fluid-filled, its shape, its size, etc., all of which help the doctor determine whether the cyst is benign and can be left alone to either regress or to be investigated some time on with another ultrasound, or whether it needs further inspection with a laparoscopy, a "keyhole" look into the pelvis.

In analyzing cysts, the larger a cyst, the greater the likelihood it's malignant, although most large cysts are benign. The age of the patient is also important: an ovarian cyst that develops after menopause is much more likely to be malignant than a premenopausal cyst is.

How are cysts treated?

Most cysts are safely left alone, and are monitored with either follow-up pelvic examination or ultrasound. Some functional cysts can regress faster when a woman starts taking the birth control pill, and this will also lower the risk of getting more cysts.

If, however, there is any question of malignancy, or if a cyst is causing problems such as irregular bleeding, a cyst will be removed for biopsy.

Sometimes removing the cyst itself is too difficult, and the whole ovary must be removed. This should not hamper the risk of future fertility, however, as the ovary on the other side will then take over producing each month's egg.

When a cyst is cancerous, the entire ovary is removed, and often the other ovary and uterus are, too.

Art Hister, MD 
in association with the MediResource Clinical Team