Ovarian cyst

An ovarian cyst is a fluid-filled sac that develops on an ovary. They're very common and do not usually cause any symptoms.

Most ovarian cysts occur naturally and go away in a few months without needing any treatment.

The ovaries

The ovaries are 2 small bean-shaped organs that are part of the female reproductive system. A woman has 2 ovaries, 1 each side of the womb (uterus).

The ovaries have 2 main functions:

to release an egg approximately every 28 days as part of the menstrual cycle
to release the female sex hormones oestrogen and progesterone, which play an important role in female reproduction

Ovarian cysts may affect both ovaries at the same time, or they may only affect 1.

Symptoms of an ovarian cyst

An ovarian cyst usually only causes symptoms if it splits (ruptures), is very large or blocks the blood supply to the ovaries.

In these cases, you may have:

pelvic pain – this can range from a dull, heavy sensation to a sudden, severe and sharp pain
pain during sex
difficulty emptying your bowels
a frequent need to urinate
heavy periods, irregular periods or lighter periods than normal
bloating and a swollen tummy
feeling very full after only eating a little
difficulty getting pregnant – although fertility is unaffected in most women with ovarian cysts

See a GP if you have persistent symptoms of an ovarian cyst.

If you have sudden, severe pelvic pain you should immediately contact either:

a GP or local out-of-hours service
NHS 111
your nearest A&E

Types of ovarian cyst

The 2 main types of ovarian cyst are:

functional ovarian cysts – cysts that develop as part of the menstrual cycle and are usually harmless and short-lived; these are the most common type
pathological ovarian cysts – cysts that form as a result of abnormal cell growth; these are much less common

Ovarian cysts can sometimes also be caused by an underlying condition, such as endometriosis.

The vast majority of ovarian cysts are non-cancerous (benign), although a small number are cancerous (malignant).

Cancerous cysts are more common in women who have been through the menopause.

Diagnosing ovarian cysts

If a GP thinks you may have an ovarian cyst, you'll probably be referred for an ultrasound scan, carried out by using a probe placed inside your vagina.

If a cyst is identified during the ultrasound scan, you may need to have this monitored with a repeat ultrasound scan in a few weeks, or a GP may refer you to a doctor who specialises in female reproductive health (gynaecologist).

If there's any concern that your cyst could be cancerous, your doctor will also arrange blood tests to look for high levels of chemicals that can indicate ovarian cancer.

But having high levels of these chemicals does not necessarily mean you have cancer, as high levels can also be caused by non-cancerous conditions, such as:

endometriosis
a pelvic infection
fibroids
your period

Treating ovarian cysts

Whether an ovarian cyst needs to be treated will depend on:

its size and appearance
whether you have any symptoms
whether you have been through the menopause

In most cases, the cyst often disappears after a few months. A follow-up ultrasound scan may be used to confirm this.

As postmenopausal women have a slightly higher risk of ovarian cancer, regular ultrasound scans and blood tests are usually recommended over the course of a year to monitor the cyst.

Surgical treatment to remove the cysts may be needed if they're large, causing symptoms or potentially cancerous.