Ovarian cysts often develop for no apparent reason in women who have monthly periods.

There are a number of different types of ovarian cyst, which are categorised as either:

• functional cysts – these are harmless cysts that form as part of the menstrual cycle, and are the most common type
• pathological cysts – tumours in the ovaries that can either be benign (harmless) or malignant (cancerous)

Functional cysts

There are two types of functional ovarian cyst:

• follicular cysts
• luteal cysts

These are described below.

Follicular cysts

Follicular cysts are the most common type of ovarian cysts.

Each month, a woman’s ovaries release an egg which travels down the fallopian tubes into the womb (uterus), where it can be fertilised by a man’s sperm.

Each egg forms inside the ovary in a tiny structure known as a follicle. The follicle contains fluid that protects the egg as it grows and it bursts when the egg is released.

However, sometimes a follicle does not release an egg, or it does not shed its fluid and shrink after the egg is released. If this happens, the follicle can get bigger as it swells with fluid. The fluid-filled follicle becomes a follicular ovarian cyst.

In most cases, only one follicular cyst develops at a time. It will often disappear without treatment after a few weeks.

Luteal cysts

Luteal cysts are less common than follicular cysts. They develop when the tissue left behind after an egg has been released (corpus luteum) fills with blood.

Luteal cysts usually disappear on their own after a few months, but they can sometimes rupture (burst), causing internal bleeding and sudden pain.

Pathological cysts

A dermoid cyst is the most common type of pathological cyst in women under 40 years of age. In women over 40, a cystadenoma is the most common type.

Dermoid cysts

Dermoid cysts develop from the cells used to create eggs. As eggs have the ability to create any type of cells, dermoid cysts can consist of a wide range of different types of human tissue, including blood, fat, bone and hair.

Dermoid cysts have the potential to grow very large. They can sometimes grow up to 15cm (6 inches) in diameter. They are not usually cancerous but often need to be surgically removed.

Cystadenomas

Cystadenomas develop from cells that cover the outer part of the ovary. There are two main types:

• serous cystadenomas
• mucinous cystadenomas

Serous cystadenomas do not usually grow very large but they can cause symptoms if they rupture.

In contrast, mucinous cystadenomas can grow very large (up to 30cm, or 12 inches), filling up the inside of the abdomen and placing pressure on other organs such as the bladder and bowel. This can cause symptoms such as indigestion and a frequent need to urinate.

Larger mucinous cystadenomas carry the risk of rupturing or blocking the blood supply to the ovaries, which is known as torsion. As with dermoid cysts, mucinous cystadenomas are rarely cancerous. 

Conditions that cause ovarian cysts

In some cases, ovarian cysts are caused by certain conditions, such as endometriosis or polycystic ovary syndrome (PCOS).

Endometriosis occurs when pieces of the tissue that line the womb (endometrium) are found outside the womb in the fallopian tubes, ovaries, bladder, bowel, vagina or rectum. Blood-filled cysts can sometimes form in this tissue.

PCOS is a condition that causes lots of small, harmless cysts to develop on your ovaries. The cysts are caused by a problem with the balance of hormones that are produced by the ovaries.

Most ovarian cysts go undiagnosed because they do not usually cause any symptoms.

Ovarian cysts are sometimes diagnosed by chance – for example, during a pelvic examination. They can also be spotted during an ultrasound scan being carried out for an unrelated reason.

If you have symptoms that could be caused by an ovarian cyst, your GP will probably refer you to a gynaecologist (a doctor who specialises in female reproductive health). They will carry out a vaginal examination to see whether they can feel any abnormal swelling.

Ultrasound scan

To confirm the presence of an ovarian cyst, you usually need to have an ultrasound scan. An ultrasound scanner uses high frequency sound waves to create an image of the inside of your body.

During the scan, a probe will be placed on your abdomen to scan your ovaries. The doctor may also place a small, tube-shaped probe inside your vagina to scan your ovaries from this angle.

An ultrasound scan can usually confirm whether you have an ovarian cyst and how big it is.

Blood test

Your GP may refer you for a blood test if an ultrasound scan shows that the cyst is partially solid rather than filled with fluid.

The blood test will be used to measure levels of a protein called CA125, which is often elevated in cases of ovarian cancer.

However, if the results of your blood test show a higher than normal level of CA125, it does not automatically mean that you have ovarian cancer.

This is because levels can fluctuate from person to person and can be raised in many other conditions, such as endometriosis (where small pieces of womb lining are found outside the womb) and tuberculosis (a bacterial infection)

Read more about how ovarian cancer is diagnosed.

An ovarian cyst is a fluid-filled sac that develops on a woman’s ovary. They are very common and do not usually cause any symptoms.

In most cases, they are harmless and usually disappear without the need for treatment. However, if the cyst is large or  causing symptoms, it may need to be surgically removed (see below).

An ovarian cyst will usually only cause symptoms if it ruptures (splits), is very large, or if it blocks the blood supply to the ovaries. If this is the case, you may have the following symptoms:

• pelvic pain 
• difficulty emptying your bowels
• a frequent need to urinate
• a change to your periods, heavy, lighter or irregular
• indigestion or a feeling of fullness and bloating
• tiredness

Read more about the symptoms of ovarian cysts.

The ovaries

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

The ovaries have two main functions. They:

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

Types of ovarian cyst

There are a number of different types of ovarian cyst. The two main types are:

• functional ovarian cysts – they develop as part of the menstrual cycle and are harmless and short-lived, they are also the most common type 
• pathological ovarian cysts – they occur as a result of abnormal cell growth (most pathological ovarian cysts are not cancerous) and are much less common

Read more about different types of ovarian cysts.

Diagnosing ovarian cysts

As most ovarian cysts do not cause symptoms, they often go undiagnosed. Or they are diagnosed by chance – for example, during a pelvic examination or ultrasound scan for an unrelated reason.

If you have symptoms that could be caused by an ovarian cyst, you will probably be referred to a gynaecologist (a doctor who specialises in female reproductive health) for a vaginal examination.

Read more about how ovarian cysts are diagnosed.

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 had the menopause (post-menopausal women have a slightly higher risk of developing ovarian cancer)

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

Due to the slightly increased risk of  post-menopausal women developing ovarian cancer, regular ultrasound scans and blood tests are usually recommended until the cyst disappears.

Large cysts, or those that cause symptoms, may need to be surgically removed. Your gynaecologist will be able to discuss this with you.

Read more about how ovarian cysts are treated.

Fertility

Ovarian cysts do not usually affect a woman’s ability to conceive.

If the cyst is large and needs to be removed, it may be possible to carry out the procedure using keyhole surgery (laparoscopy), which may help preserve your fertility.

However, exactly how this is managed will depend on the specific features of the cysts, the blood results and the clinical findings in each individual case.

In most cases, ovarian cysts do not cause any symptoms.

You will usually only have symptoms if you have a cyst that:

• ruptures (splits)
• is very large
• blocks the blood supply to the ovaries (torsion)

In these cases, you may have the following symptoms:

• pelvic pain – this can range from a dull, heavy sensation (associated with large cysts) to a sudden, sharp pain (associated with a ruptured cyst or torsion) 
• pelvic pain during sexual intercourse
• difficulty emptying your bowels
• frequent need to urinate
• changes to your normal menstruation – you may have heavy periods, irregular periods or lighter periods than normal
• a feeling of fullness and bloating
• indigestion or feeling very full, even though you have only eaten a little
• lightheadedness or dizziness
• extreme tiredness (fatigue) 

When to seek medical advice

You should contact your GP if you are experiencing any of the above symptoms. If this is not possible, telephone your local out-of-hours service or NHS 111.

In most cases, ovarian cysts disappear on their own without the need for treatment.

If you have an ovarian cyst, whether it needs to be treated will depend on:

• its size and appearance 
• whether you have any symptoms
• whether you have had the menopause (post-menopausal women have a slightly higher risk of developing ovarian cancer)

Watchful waiting

In most cases, a policy of “watchful waiting” is recommended, where you receive no immediate treatment. This is because most cysts disappear after a few weeks without the need for treatment. A follow-up ultrasound scan will help confirm whether this is the case.

Because of the slightly increased risk of post-menopausal women developing ovarian cancer, regular ultrasound scans and blood tests are usually recommended until the cyst disappears.

Surgery

Large ovarian cysts or cysts that are causing symptoms will usually need to be removed.

Doctors sometimes recommend removing cysts even when they are not causing symptoms. This is because it is not always possible to tell what type of cyst it is without closely examining it under a microscope. Removing the cyst also significantly reduces the risk of it becoming cancerous later on.

There are two types of surgery that can be used to remove ovarian cysts. They are:

• a laparoscopy
• a laparotomy

Both procedures are usually carried out under general anaesthetic (medication used to provide pain relief during surgery).

Laparoscopy

Smaller cysts can sometimes be removed using a procedure known as a laparoscopy. This is a type of keyhole surgery where small cuts are made in your lower abdomen and gas is blown into the pelvis to lift the wall of your abdomen away from the organs inside.

A laparoscope, which is a small, tube-shaped microscope with a light on the end, will be passed into your abdomen so the surgeon can see your internal organs. Using tiny surgical tools, the surgeon will remove the cyst through the small cut in your skin.

After the cyst has been removed, the cuts will be closed using dissolvable stitches. Depending on the type and size of cyst, the operation usually takes about an hour. Most women are able to go home later on the same day or the following day.

A laparoscopy is the preferred surgical method because it causes less pain and allows you to resume normal activity sooner.

Laparotomy

If there is a chance that your cyst is cancerous, a more invasive procedure called a laparotomy may be recommended.

During a laparotomy, a larger cut will be made to give the surgeon better access to the cyst. Depending on the size of the cyst, this may be along your bikini line or in the midline of your tummy. 

The whole cyst and ovary will be removed so that it can be sent to a laboratory to check whether it is cancerous. Stitches or staples will be used to close the incision.

After the procedure, you will have a catheter (a tube in your bladder to drain urine) and a drip. You may need to stay in hospital for a few days after the procedure.

Your fertility

If only one of your ovaries is removed, your remaining ovary will continue to function normally if you are pre-menopausal. It will release hormones and eggs as usual, which means that your health and fertility should be unaffected, although your fertility may be slightly reduced.

If both of your ovaries need to be removed, this will trigger an early menopause (if you have not already reached the menopause). However, it may still be possible to have a baby by having a donated egg implanted into your womb. This will need to be discussed with specialists at a centre that specialises in assisted reproduction techniques.

Your surgeon will try to preserve as much of your reproductive system as possible. For example, it may be possible to preserve your ovary and fallopian tube (the tube where the egg passes), which will have a minimal effect on your fertility. This procedure is known as an ovarian cystectomy.

Following an ovarian cystectomy, you may be able to return to work within two weeks. However, if the cyst is very large and the whole tube covers the ovary or there are concerns about the nature of the cyst, the whole tube and ovary may need to be removed.

In this case, your recovery may still only be two weeks if the procedure is carried out laparoscopically. If an “open” approach is used, such as a laparotomy, your recovery may take six to eight weeks.

The results may take three to four weeks to come back. A plan for further management will either be sent to you by your consultant through the post or a follow-up hospital appointment may be arranged.

Cancer treatment

If laboratory results show that the cyst is cancerous, both of your ovaries, your womb (uterus) and some of the surrounding tissue may need to be removed.

Again, this would trigger an early menopause and mean that you would be infertile.

Read more about treating ovarian cancer.