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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 are 2 almond-shaped organs that are part of the female reproductive system. There's 1 on 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 sex hormones oestrogen and progesterone, which play an important role in reproduction

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

An ovarian cyst usually only causes symptoms if it splits (ruptures), is very large or twists and then 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 usually unaffected by ovarian cysts

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

Ask for an urgent GP appointment or get help from NHS 111 if:

• you have sudden, severe pelvic pain
• you have pain in your tummy (abdomen) and you also feel sick (nausea) or are being sick (vomiting)

You can call 111 or get help from 111 online

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 if you have been through the menopause.

Find out more about the causes of 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, the 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

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 disappears after a few months. A follow-up ultrasound scan may be used to confirm this.

If you are postmenopausal, there is 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.

Ovarian cysts do not usually prevent you getting pregnant, although they can sometimes make it harder to conceive.

If you need an operation to remove your cysts, your surgeon will aim to preserve your fertility whenever possible.

This may mean removing just the cyst and leaving the ovaries intact, or only removing 1 ovary.

In some cases, surgery to remove both your ovaries may be necessary, in which case you'll no longer produce any eggs.

Make sure you talk to your surgeon about the potential effects on your fertility before your operation.