What are ovarian cysts?
An ovarian cyst is a sac of tissue that develops inside an ovary. It is very common, usually painless and will often go away without treatment. Ovarian cysts can affect women of any age. Most ovarian cysts are small, although some may reach a large size.
There are several different kinds of ovarian cyst, which are categorised as either:
- Functional cysts (the most common type): harmless cysts that form as part of the menstrual cycle.
- Pathological cysts: tumours in the ovaries that are either benign (harmless) or malignant (cancerous).
Functional ovarian cysts / simple cysts
There are two types of functional ovarian cyst:
- Follicular cyst.
- Luteal cyst.
Follicular cysts are the most commonly seen ovarian cysts. The ovaries are two small, bean-shaped organs that are part of the female reproductive system. They release an egg every month, which moves into the womb (uterus) where it is fertilised by a man's sperm. Each egg forms in a tiny structure inside the ovary called a follicle. The follicle contains fluid to protect 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. Usually, only one cyst appears at a time and it will often disappear without treatment after a few weeks.
Luteal cysts are less common than follicular cysts. They develop when the tissue that is left behind after an egg has been released, known as the corpus luteum, fills with blood. Luteal cysts usually disappear on their own, within a few months, but they can sometimes rupture (burst), causing internal bleeding and sudden pain.
A dermoid cyst, is the most common type of pathological cyst in women who are under 40 years old. In women over 40 years of age, a ‘cystadenoma’ is the most common type.
Dermoid cysts develop from the cells that are 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 will usually need to be surgically removed.
Cystadenomas develop from cells that cover the outer part of the ovary. There are two main types of cystadenomas:
- 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 result in symptoms such as:
- A frequent need to urinate.
Larger mucinous cystadenomas carry the risk of rupturing, or blocking the blood supply to the ovaries (torsion). As with dermoid cysts, mucinous cystadenomas are rarely cancerous.
How common are ovarian cysts?
Ovarian cysts are very common. It is estimated that virtually all women who still have a monthly period, and 1 in 5 women who have been through the menopause, will have one or more ovarian cysts. Ovarian cysts that cause symptoms are much less common, affecting only 1 in every 25 women at some point in their life.
Ovarian cysts and fertility
Ovarian cysts usually do not affect a woman's ability to conceive. Even if the cyst is larger and needs to be removed, this is usually done using laparoscopy (using ‘keyhole’ surgery), which preserves a woman's fertility.
What are the symptoms of ovarian cysts?
An ovarian cyst will usually only cause symptoms if:
- It ruptures (splits).
- t is very large.
- It blocks the blood supply to the ovaries (torsion).
Under such circumstances, you may have the following symptoms:
- Pelvic pain, which can range from a dull heavy sensation (associated with large cysts) to a sudden, sharp pain (which is associated with a ruptured cyst or torsion).
- Difficulty emptying your bowels.
- Pelvic pain during sexual intercourse.
- A frequent need to urinate.
- Changes to your normal menstruation – you may develop irregular periods, heavy periods or lighter periods than usual.
- A feeling of fullness and bloating.
- Indigestion or feeling very full even though you have only eaten a little.
Sometimes, ovarian cysts cause more serious problems, which are outlined below. These types of cyst will need hospital treatment.
- Torsion If a cyst is growing on a stem from an ovary, the stem can become twisted (called torsion). This stops the blood supply to the cyst and causes a lot of pain in the lower abdomen.
- Bursting- The cyst may burst, causing sudden severe pain in the lower abdomen. The pain you feel depends on what the cyst contained, whether it is infected and whether there is any bleeding.
- Cancer- Very occasionally, an ovarian cyst is an early form of ovarian cancer. However, ovarian cysts are very common and about 95% are non-cancerous.
Conditions that cause ovarian cysts
If you have endometriosis, you may develop ovarian cysts. Endometriosis occurs when pieces of the tissue that lines the womb (the endometrium) are found outside the womb in areas such as the fallopian tubes, ovaries, bladder, bowel, vagina or rectum. Sometimes, blood-filled cysts can form in this tissue. (Read more about endometriosis)
- Polycystic ovarian syndrome
Polycystic ovarian syndrome is a condition that causes lots of small, harmless cysts to develop on your ovaries. The cysts develop if there is a problem with the balance of hormones that are produced by the ovaries. (Read more about PCOS)
How are ovarian cysts diagnosed?
Most ovarian cysts do not cause any symptoms, therefore they often can go undiagnosed. Sometimes, ovarian cysts are diagnosed by chance – for example, during a pelvic examination. They can also be spotted when people have an 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). The gynaecologist will carry out a vaginal examination to see whether they can feel any abnormal swelling.
To confirm an ovarian cyst, you usually need to have an ultrasound scan. An ultrasound scanner works by using sound waves to build up an image of the inside of your body. The probe of the scanner is placed on your abdomen to scan your ovaries. The doctor/sonographer may also put a small, tube-shaped probe inside your vagina to scan your ovaries from this angle (a trans-vaginal scan). An ultrasound scan can usually confirm whether you have an ovarian cyst and how big it is.
You may be referred for a blood test if an ultrasound scan shows that the cyst is partially solid, as opposed to being 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. If your blood test shows a higher than normal level of CA125, it does not automatically mean that you have ovarian cancer because levels can fluctuate from person to person.
MRI or CT scan
What is the treatment for ovarian cysts?
If you have an ovarian cyst, whether it needs to be treated will depend on:
- Its appearance and size.
- Whether you have any symptoms.
- Whether you have had the menopause (post-menopausal women have a slightly higher risk ofdeveloping ovarian cancer).
In the majority of cases especially for simple cysts, a policy of ‘watchful waiting’ will be recommended where you receive no immediate treatment. This is because most cysts will disappear without the need for treatment. A follow-up ultrasound scan will usually confirm that this is the case.
In most simple cysts, you will given the following options:
A simple cyst that measures less than 5cm in diameter-
Normally, treatment is not necessary. These cysts usually disappear on their own after a few months. You are unlikely to need a follow-up appointment.
A simple cyst that measures 5–7cm in diameter-
You should be offered follow-up, usually an ultrasound scan a year later.
A simple cyst that measures more than 7cm in diameter-
You may be offered further tests, such as magnetic resonance imaging (MRI) and/or surgery.
Due to the slightly higher risk of ovarian cancer in women who have experienced the menopause, regular ultrasound scans and blood tests are usually recommended until the cyst disappears or reduces in size. The scans and the blood tests will be done every four months, if the cyst remains the same size in one year after three scans, you are likely to be discharged.
If the cyst increases in size, you will be advised to have surgery and removal of the ovary.
If the cyst is large, or if it is causing symptoms, it will probably need to be removed. Doctors sometimes recommend removing the cyst even if it is not causing symptoms. This is because it is
not always possible to tell what type of cyst it is without looking at it under a microscope. Removing it also reduces the risk of the cyst becoming cancerous later on.
There are two types of operation, which are usually carried out under general anaesthetic (you will be asleep during the operation and will feel no pain). They are:
Smaller cysts can sometimes be removed using a surgical technique called 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 the abdomen away from the organs inside.
A laparoscope, which is a small, tube-shaped microscope with a light on the end, is passed into your abdomen so that the surgeon can see your internal organs. Using tiny surgical tools,
the surgeon will be able to remove the cyst through the small cut in your skin.
After the procedure, the cuts are closed using dissolvable stitches. The operation takes about half an hour to two hrs to perform, depending on the size and type of cyst. Most women can go
home on the same day as the operation. A laparoscopy is the preferred approach because it causes less pain, helps to preserve fertility and lets you resume normal activity sooner.
If there is a risk that the cyst is cancerous, a more invasive procedure called a laparotomy may be recommended. During a laparotomy, a larger cut is made to give the surgeon better access to the cyst. The whole cyst and ovary is removed and sent to a laboratory to check whether it is cancerous. The skin is then closed using stitches. You may have to stay in hospital overnight or for a few days.
If only one of your ovaries is removed, your remaining ovary will still release hormones and eggs as normal, so your health and fertility should be unaffected.
If both ovaries needed to be removed then this would trigger an early menopause (if you had not already gone through the menopause).
However, it may still be possible to have a baby by having a donated egg implanted into your womb.
Treatment for cancer
If the cyst is found to be cancerous, you may need to have treatment to remove both of your ovaries, your womb (uterus) and some of the surrounding tissue.
This would trigger an early menopause and means that you would be no longer able to have children.