We discuss ovarian cysts

Ovarian cysts are fluid-filled sacs that form in or on an ovary. They are very common, usually form as part of ovulation, and are mostly harmless. Many women with ovarian cysts have no symptoms and never know they have one. In this post I explain the different types of ovarian cysts, the symptoms to look out for, and when a cyst may need treatment.

How common are ovarian cysts?

Ovarian cysts are common in women who have regular periods. In fact, most women make at least one small cyst every month as part of the normal cycle. You may not know you have one unless it grows, causes a problem or several form at once. About 8% of women before the menopause develop large cysts that need treatment.

Ovarian cysts are less common after the menopause, and in postmenopausal women they carry a higher risk of being cancerous. At any age, see your doctor if you think you have a cyst, or if you have bloating, need to pass urine more often, feel pelvic pressure or pain, or have unusual vaginal bleeding.

Types of ovarian cysts

The most common ovarian cysts are called functional cysts. They form during the menstrual cycle and are almost always benign (not cancerous):

• Follicle cysts: each month, an egg grows inside a small sac called a follicle, which normally breaks open to release it. If the follicle does not break open, it can keep growing into a cyst. These cysts often cause no symptoms and go away in one to three months.
• Corpus luteum cysts: after the egg is released, the empty follicle normally shrinks. If it reseals and fills with fluid instead, a cyst forms. Most go away within a few weeks, but they can grow to about 10cm across, and may bleed or twist the ovary and cause pain.

Other benign ovarian cysts are less common:

• Endometriomas are caused by endometriosis.
• Dermoid cysts come from cells present from birth and do not usually cause symptoms.
• Cystadenomas are filled with watery fluid and can sometimes grow large.

In polycystic ovary syndrome (PCOS), the ovaries contain many small follicles, which can affect periods and fertility. Cancerous cysts are rare and more common in older women, but this is why ovarian cysts should always be checked. Our ovarian cancer page explains the warning signs.

Symptoms of ovarian cysts

Most ovarian cysts are small and cause no symptoms. When they do, you may feel pressure, bloating, swelling or pain in the lower tummy on the side of the cyst, and the pain may be sharp or dull and come and go. Less common symptoms include pelvic pain, a dull ache in the lower back and thighs, difficulty emptying the bladder or bowel, pain during sex or during your period, unusual bleeding and breast tenderness.

If a cyst bursts, it can cause sudden, severe pain. If it twists the ovary, you may have severe pain with nausea and vomiting. Both need urgent medical attention.

How are ovarian cysts diagnosed and treated?

An ultrasound scan is usually the first test, and a blood test may be added depending on your age and the scan findings. Many cysts simply need monitoring with a repeat scan. If a cyst needs to come out, your surgeon will remove either the cyst alone or the whole ovary:

• Laparoscopy (keyhole surgery): a small cut near the belly button allows the surgeon to remove the cyst. This is often recommended for smaller cysts that look benign on ultrasound; see key-hole surgery for fibroids and cysts.
• Laparotomy: a larger cut in the tummy, used if the cyst is very large or may be cancerous. The cyst is then tested, and if cancer is likely, a gynaecological oncologist may need to remove the ovary and other tissues, such as the womb.

Cancer Research UK explains which ovarian symptoms need checking, and NICE sets out how ovarian masses should be assessed. Our ovarian cysts page has more detail. If you have been told you have an ovarian cyst, you can book an appointment with Mr Jafaru Abu at The Park Hospital, Nottingham.