An ovarian cyst is any collection of fluid, surrounded by a very thin wall (a sac), inside or on an ovary. Any ovarian follicle that is larger than about two centimeters is termed an ovarian cyst. An ovarian cyst can be as small as a pea or larger than an orange.
Most ovarian cysts are functional in nature and harmless (benign). In the US, ovarian cysts are found in nearly all premenopausal women, and in up to 14.8% of postmenopausal women. Ovarian cysts affect women of all ages. They occur most often, however, during a woman's childbearing years. Some ovarian cysts cause problems, such as bleeding and pain. Surgery may be required to remove cysts larger than 5 centimeters in diameter.
Some or all of the following symptoms may be present, though it is possible not to experience any symptoms:
- Dull aching, or severe, sudden, and sharp pain or discomfort in the lower abdomen (one or both sides), pelvis, vagina, lower back, or thighs; pain may be constant or intermittent—this is the most common symptom;
- Fullness, heaviness, pressure, swelling, or bloating in the abdomen;
- Breast tenderness;
- Pain during or shortly after beginning or ending the menstrual period;
- Irregular periods, or abnormal uterine bleeding or spotting;
- Change in frequency or ease of urination (such as inability to fully empty the bladder), or difficulty with bowel movements due to pressure on adjacent pelvic anatomy;
- Weight gain;
- Nausea or vomiting;
- Increased level of hair growth;
- Increased facial hair or body hair;
- Strange pains in ribs, which feel muscular;
- Strange nodules that feel like bruises under the layer of skin.
About 95% of ovarian cysts are benign (Figure 1). Cysts that persist beyond two or three menstrual cycles, or occur in post-menopausal women, may indicate more serious disease and should be investigated through ultrasonography and laparoscopy, especially in cases where family members have had ovarian cancer. Such cysts may require surgical biopsy. Additionally, a blood test may be taken before surgery to check for elevated CA-125, a tumor marker, which is often found in increased levels in ovarian cancer, although it can also be elevated by other conditions resulting in a large number of false positives.
For more serious cases where cysts are large and persisting, doctors may suggest surgery. Some surgeries can be performed to successfully remove the cyst(s) without hurting the ovaries, while others may require removal of one or both ovaries.
There are several other conditions affecting the ovary that are described as types of cysts, but are not usually grouped with the functional cysts (Some of these are more commonly or more properly known by other names). These include:
- Dermoid cyst
- Chocolate cyst
- A polycystic-appearing ovary
- Ovarian serous cystadenoma
- Ovarian mucinous cystadenoma
A chocolate cyst is an endometrioma, endometrioid cyst, endometrial cyst, or chocolate cyst is caused by endometriosis, and formed when a tiny patch of endometrial tissue (the mucous membrane that makes up the inner layer of the uterine wall) bleeds, sloughs off, becomes transplanted, and grows and enlarges inside the ovaries.
A polycystic-appearing ovary is diagnosed based on its enlarged size — usually twice normal —with small cysts present around the outside of the ovary. It can be found in women with normal ovaries, and in women with endocrine disorders. An ultrasound is used to view the ovary in diagnosing the condition. Polycystic-appearing ovary is different from the polycystic ovarian syndrome, which includes other symptoms in addition to the presence of ovarian cysts.