What causes an ovarian cyst?

The most common non-cancerous ovarian cysts are follicle cysts and corpus luteum cysts.

Other non-cancerous types are:

• endometriomas, caused by endometriosis
• dermoids, from cells present from birth
• cystadenomas, which are filled with watery fluid.

Cancerous cysts are rare and are called ovarian cancer.

Ovarian cyst types

Follicle cysts

Each month, during a normal menstrual cycle, your ovaries release an egg which has grown in a tiny follicle or sac. Follicle cysts occur when this sac doesn’t break open and release the egg. Instead, it continues growing and forms a cyst.

Follicle cysts may not have symptoms and usually go away in one to three months.

Corpus luteum cysts

Corpus luteum cysts form if the follicle sac doesn’t shrink after it releases the egg, but instead re-seals itself. Fluid then builds up inside the sac and forms a cyst.

These cysts usually go away in a few weeks but they can grow quite large – up to 10 cm in size. They can sometimes bleed or twist the ovary causing pain.

Ovarian cyst diagnosis

You should see your doctor if you think you have an ovarian cyst or have symptoms such as:

• bloating
• needing to urinate more often
• pelvic pressure or pain
• unusual vaginal bleeding
• pain during sexual intercourse.

Your doctor may conduct a physical examination and suggest tests including:

• imaging tests, such as an ultrasound
• blood tests
• laparoscopy.

Ovarian cysts treatment

Most ovarian cysts go away without treatment.

If tests indicate your cyst is non-cancerous, your doctor may suggest no treatment is necessary but that you have regular checkups. If the cyst doesn’t go away, grows, or causes pain, or if the cyst may be cancerous, your doctor may suggest surgery.

Polycystic ovary syndrome

Some women develop polycystic ovary syndrome (PCOS), which occurs when the ovaries make many small cysts. PCOS is a hormonal condition and affects one in 10 to 20 women. If you have it, your ovaries will be enlarged and contain many small, fluid-filled cysts.

It occurs when your ovaries produce too much androgen – a male hormone. Women with PCOS sometimes develop excess face and body hair, acne, hair loss – similar to male baldness – and fat deposits around the abdomen.

PCOS is a leading cause of infertility, yet many women do not know they have it.