Ovarian cysts

What is an ovarian cyst?

An ovarian cyst is a fluid-filled sac that develops on or inside one of your ovaries, the two small organs that sit either side of your womb. They're very common, usually harmless, and most disappear on their own within a few months.

What are the symptoms of an ovarian cyst?

Most ovarian cysts don't cause any symptoms at all, and you may only find out you have one if it's picked up during an examination or scan for something else. When a cyst does cause symptoms, this usually happens because it has grown large, ruptured or twisted.

If you do have symptoms, they can include:

• pelvic pain or pressure, which can range from a dull ache to sudden, severe pain, often worse on one side
• bloating or a swollen abdomen, or feeling full quickly after eating
• pain during sex
• heavier, lighter or more irregular periods than usual, or discomfort mid-cycle
• needing to pass urine more often, or difficulty fully emptying your bladder or bowel
• a dull ache in your lower back or thighs.

Some symptoms need urgent attention. Seek immediate medical help if you have sudden, severe abdominal or pelvic pain, especially alongside vomiting, fever, feeling faint or dizzy, or pain in the tip of your shoulder, since these can be signs that a cyst has ruptured or that your ovary has twisted (torsion), cutting off its blood supply. Torsion in particular is a medical emergency that usually needs urgent surgery.

What are the causes of ovarian cysts and who is at risk?

Most ovarian cysts form as a normal part of ovulation, when the sac that releases your egg each month (the follicle) doesn’t release it, or doesn’t shrink away afterwards. This is why they’re much more common before the menopause, and why they’re described as ‘functional’ cysts.

Cysts can also be caused, less commonly, by:

• endometriosis, where tissue similar to the womb lining grows elsewhere and can form blood-filled cysts on your ovary
• polyendocrine metabolic ovarian syndrome (PMOS) – formerly known as polycystic ovary syndrome (PCOS) – which causes many small cysts to form as a result of altered hormone levels
• a severe pelvic infection that has spread to your ovaries
• abnormal cell growth, which can lead to other, less common cyst types.

You're more likely to develop an ovarian cyst if you haven't yet gone through the menopause, are pregnant, have had a cyst before, have a hormone-related condition such as endometriosis or PMOS, or are taking fertility medicines that stimulate ovulation.

Are there different types of ovarian cyst?

Ovarian cysts fall into two broad groups.

Functional cysts are linked to your menstrual cycle and are the most common type. They include follicular cysts, which form when a follicle doesn't release its egg, and corpus luteum cysts, which form after an egg is released if the empty follicle reseals and fills with fluid or blood. Both are usually harmless and typically resolve within 6 to 8 weeks without treatment.

Pathological cysts form as a result of abnormal cell growth rather than the menstrual cycle, and can develop before or after the menopause. The main types are:

• Dermoid cysts (teratomas): These contain tissue such as skin, hair or teeth and are usually benign, but often need a surgical opinion
• Cystadenomas: These form on the surface of the ovary, are filled with watery or thicker fluid, and tend to grow over time
• Endometriomas: These are filled with old blood and linked to endometriosis, which usually need gynaecology follow-up
• Ovarian cancer cysts: These are solid rather than fluid-filled and are much less common, though more likely after the menopause.

The vast majority of ovarian cysts, of any type, are non-cancerous. Fewer than 1% are cancerous overall, though the odds shift somewhat with age and with certain features seen on a scan.

How are ovarian cysts diagnosed?

If your GP thinks you might have an ovarian cyst, you'll usually be referred for an ultrasound scan, often carried out using a small probe placed inside your vagina (a transvaginal scan), sometimes combined with a scan over your abdomen.

This is an intimate examination, so a chaperone will be present, and you can ask for a female doctor or health professional to carry it out if one is available. Your doctor may also want to rule out pregnancy first, since some pregnancy complications can look similar to a cyst.

The scan shows the cyst's size, shape and location, and whether it's fluid-filled, solid, or a mix of both, which helps your doctor judge how likely it is to be harmless. Simple, clear, fluid-filled cysts are reassuring at any age – features such as solid areas, internal blood flow or fluid elsewhere in the pelvis prompt closer review.

If there's any concern that a cyst could be cancerous, particularly if you've been through the menopause, you may also have a blood test for CA-125, a protein that tends to be higher with ovarian cancer. A raised result doesn't necessarily mean cancer, though, since it can also be raised by conditions such as endometriosis, fibroids, a pelvic infection, or even your period.

A cyst found on a scan may simply be monitored with a repeat scan a few weeks or months later, or your GP may refer you to a gynaecologist, particularly if the cyst is complex-looking, large, or you’ve been through the menopause, when follow-up tends to be closer.

How are ovarian cysts treated?

Non-surgical treatment

Most ovarian cysts need no active treatment and go away by themselves within a few months, confirmed with a follow-up scan.

If you're getting cysts often, your doctor may suggest hormonal birth control, such as the pill, to stop ovulation and reduce the chances of new cysts forming; this won't shrink a cyst you already have, but can help prevent further ones. Pain relief, such as paracetamol or anti-inflammatory painkillers, can help with any discomfort in the meantime.

If you’ve had ovarian cysts and gone through the menopause, you’re usually monitored more closely, with regular ultrasound scans and blood tests over the course of a year, since the risk of cancer is slightly higher at this stage of life.

Surgical treatment

Surgery is usually recommended if a cyst is large, persistent, causing symptoms, or if there's any concern it could be or become cancerous. There are two main approaches:

• Laparoscopy (keyhole surgery): The cyst is removed through small cuts in your abdomen using a camera and instruments. This is preferred where possible, since it causes less pain and a quicker recovery
• Laparotomy (open surgery): This involves a larger cut, which may be needed for very large cysts or where there’s a stronger suspicion of cancer.

Your surgeon will aim to preserve your fertility wherever possible, for example by removing only the cyst, or only one ovary, and will talk to you about the potential effects on your fertility before any operation.

If a cyst turns out to be cancerous, more extensive surgery may be needed, sometimes removing both ovaries, your womb, and surrounding tissue – this would bring on an early menopause and mean you could no longer get pregnant naturally.

When should I see a doctor? See a GP if you notice symptoms of an ovarian cyst, such as pelvic pain, bloating, or changes to your periods.

Get an urgent GP appointment or call 111 if you have sudden, severe pelvic pain, or abdominal pain along with feeling or being sick. Seek emergency care if severe pain comes on suddenly with fever, vomiting, fainting, dizziness or shoulder-tip pain, as these can indicate a ruptured cyst or ovarian torsion.