An ovarian cyst is a fluid-filled sac that forms on or inside an ovary. Ovarian cysts are very common. Almost every woman will have one at some point in her life.

Most cysts are harmless and cause no symptoms. Many form as a normal part of your monthly cycle and go away on their own within a few months. Some cysts do cause pain, or grow larger, or need a closer look to be sure what they are.

The chance of a cyst being harmful is low, but it rises with age. After menopause, a new cyst is checked more carefully, because the small risk of a harmful cyst is higher at that stage of life.

There are several types of ovarian cyst. Most are harmless. The type helps guide whether a cyst needs treatment.

These are the most common type. They form as part of your normal monthly cycle, and they are harmless. There are two kinds:

• A follicular cyst forms when the sac that holds an egg keeps growing instead of releasing the egg.
• A corpus luteum cyst forms when that sac seals over after the egg is released and fills with fluid.

Functional cysts usually go away on their own within 2 to 3 months. While you have one, your period may come late. It usually settles once the cyst has gone.

A dermoid cyst is made from cells from different cell lines. It can contain tissue such as hair, fat, skin or teeth. Dermoid cysts are one of the more common cysts in younger women. They are almost always harmless, but they do not go away on their own and may need to be removed.

These cysts form on the surface of the ovary and are filled with a watery or a thicker, jelly-like fluid. They can grow large and may need to be removed.

An endometrioma, sometimes called a “chocolate cyst”, is a cyst filled with old blood. It forms when endometriosis affects an ovary. These cysts can cause pain and can make it harder to become pregnant.

Most ovarian cysts cause no symptoms and are found by chance on a scan. A larger cyst is more likely to cause problems. Symptoms can include:

• Bloating or a feeling of fullness in the lower stomach
• Pelvic pain, pressure or a dull ache
• Needing to pass urine more often
• Pain during sex

A cyst is one of several possible causes of ongoing pelvic pain, along with fibroids, endometriosis and heavy or painful periods. Because the causes overlap, it is worth having ongoing symptoms checked.

Sometimes a cyst bursts (ruptures), or a cyst causes the ovary to twist (torsion), which cuts off its blood supply. Both can cause sudden, severe pain. Larger cysts are more likely to cause these problems.

Seek urgent medical help if you have:

• Sudden, severe pain in the lower stomach or pelvis
• Pain with fever or vomiting
• Feeling faint, dizzy or very unwell, with cold, clammy skin or fast breathing

If you have symptoms, Dr Mahadik will ask about them and examine you. A cyst is often found on a scan done for another reason.

• Ultrasound is the main test. It shows the size, position and make-up of a cyst, and whether it is filled with fluid or has solid components. It can be done over the lower stomach or through the vagina.
• A pregnancy test may be done, as some cysts are linked to early pregnancy.
• Blood tests may be used in some cases. One of these is a blood test called CA-125.

CA-125 is a protein that can increase in a range of different conditions. It may also increase in women with suspected ovarian tumours. It is not a screening test for ovarian cancer on its own. Common, harmless conditions such as endometriosis, fibroids and pelvic infection can raise the level too. For this reason it is used mainly alongside an ultrasound. It is mostly used in women who have been through menopause, where it helps guide the next step. Dr Mahadik will explain whether this test is useful in your situation.

The right approach depends on the type and size of the cyst, your symptoms, your age, and whether you have been through menopause. Dr Mahadik talks through the options with you so you can decide together.

Many cysts need no treatment. If a cyst is small and looks harmless, Dr Mahadik may suggest a repeat scan in a few weeks or months. This checks that it has gone, or has not changed. Most functional cysts settle on their own.

Pain relief you can buy over the counter can help with mild discomfort. If you often get functional cysts, the combined pill or another hormonal option may lower the chance of new ones forming. Do not stop or change any prescribed medicine without medical advice.

Surgery may be advised if a cyst is large, does not go away, causes pain, looks unusual on a scan, or appears after menopause. A cyst that is removed is sent to the laboratory to be checked. There are two main ways to do this:

• Laparoscopy (keyhole surgery) is the most common method. Small cuts are made near the belly button, and a camera and fine instruments are used to remove the cyst. Recovery is usually quicker than with open surgery.
• Laparotomy (open surgery) uses one larger cut. It may be used for a very large cyst, or when a cyst looks like it could be harmful.

Where possible, the aim is to remove only the cyst and keep the ovary. Sometimes the whole ovary needs to be removed. If there is a concern that a cyst could be cancer, care may be shared with a gynaecological cancer specialist (a gynae-oncologist). Dr Mahadik will explain what is planned and why before any surgery.

Most ovarian cysts do not affect your chance of becoming pregnant. Functional cysts, the most common type, have no effect on fertility.

Some cysts can matter. An endometrioma can make it harder to become pregnant, because it is linked to endometriosis. If you are having trouble falling pregnant, Dr Mahadik can look into the cause and, where helpful, talk with you about fertility and infertility options.

Cysts are also common in pregnancy. Most cause no problems and go away on their own. A cyst found in pregnancy is usually watched with scans, in case it grows or causes pain.