What you need to know about ovarian cysts

Ovarian cysts are fluid-filled sacs that grow on the ovaries. They are very common in women before menopause and, in most cases, do not cause any symptoms. Consequently, most women become aware that they have an ovarian cyst incidentally, for example, when having an ultrasound scan to investigate another condition.

How do ovarian cysts form?

Ovarian cysts form from follicles, which are small fluid-filled sacs that protect the eggs (ova) in your ovaries as they grow. 

Normally, a follicle bursts to release its egg during ovulation and then, releases its fluid and shrinks. However, in some cases, the follicle either doesn’t release its egg or after releasing its egg, doesn’t release its fluid and shrink. In these situations, the follicle can continue to grow and consequently, form an ovarian cyst. 

Most follicles are two to three centimetres in size; when a follicle becomes larger than three centimetres, it is considered a cyst. In some cases, cysts can produce symptoms, which is when most women become aware that they have a cyst, if it hasn’t already been detected incidentally during an ultrasound scan. 

Types of ovarian cysts

There are two main types of ovarian cysts: simple cysts and complex cysts. 

Simple cysts occur when the follicle continues to grow after releasing its egg. These are the most common type of ovarian cyst and contain only fluid. They usually go away without treatment after three to four months. 

Complex cysts are less common and contain solid tissue or blood. They can be further categorised into cystadenomas, dermoid cysts and endometriomas.

Dermoid cysts develop from special cells called germ cells that have the ability to form lots of different tissues. This means dermoid cysts can contain several different types of tissue, including hair, skin, fat and teeth.

Endometriomas are cysts made of cells that normally line your womb (endometrium) but have grown outside of your womb; they are a feature of endometriosis. Cystadenomas are cysts made of ovarian tissue and also contain fluid or mucus.

The vast majority of ovarian cysts are not cancerous; however, in rare cases, a complex ovarian cyst may develop into ovarian cancer. It is important to note that ovarian cancer is rare in women before menopause. 

Ovarian cyst symptoms

Most ovarian cysts do not cause any symptoms; however, when symptoms do occur, they commonly include lower abdominal pain, painful periods, irregular periods or a change in the pattern of your periods.

If the cyst is on the back of your cervix (neck of the womb) or you have endometriosis, you may also experience pain during sex. 

In rare cases, when a cyst is pressing against the bladder, you may experience a frequent urge to urinate. 

If your cyst is cancerous, you may feel bloated, lose your appetite and easily feel full after eating. 

If you notice any of the above symptoms, see your GP.

Symptoms of a burst ovarian cyst

Most ovarian cysts do not rupture (burst) and when an ovarian cyst does rupture, it may not cause any symptoms or only mild symptoms that can be managed with over-the-counter painkillers. 

However, in some cases, ruptured ovarian cysts can cause severe symptoms including nausea, vomiting, severe abdominal pain that leaves you doubled over, cold clammy hands, dizziness and vaginal bleeding. You should seek urgent medical care if you develop any of these symptoms.

Ovarian cysts and fertility

In most cases, ovarian cysts do not reduce your fertility. However, if you have endrometriomas, your ovarian reserve may be reduced — this means you will have fewer eggs, which can consequently affect your fertility. 

Endometriosis can also cause inflammatory reactions in your reproductive system that can reduce fertility too. 

Getting a diagnosis

Ovarian cysts are detected using an ultrasound scan, either with an ultrasound wand moved over your abdomen (transabdominal ultrasound scan) or with an ultrasound probe inserted into your vagina (transvaginal ultrasound scan).

If you have a complex cyst, you may need an MRI scan and blood test to help identify specific features of your cyst.

Treating ovarian cysts

Simple cysts up five centimetres in size do not need any treatment or monitoring and will resolve on their own after three to four months. If you have a simple cyst that is five to seven centimetres in size, you will need regular ultrasound scans, from one to four times a year, to monitor it.

If you have a simple cyst that is larger than seven centimetres, there is a greater risk that it will become twisted, bleed, leak or rupture. You will, therefore, need regular ultrasound scans and will need to remain vigilant of signs of a rupture so that you can seek medical help as soon as possible. 

For very large ovarian cysts, you may need laparoscopic (keyhole) surgery to remove your cyst. If you are unable to undergo surgery and have a very large simple cyst, it may be possible to drain your cyst with a minimally invasive, ultrasound-guided procedure. 

If your cyst can’t be separated from your ovary, you may need surgery to remove your entire ovary (oophorectomy).

Complications and side effects of ovarian cyst surgery

Every surgery, including surgery to remove an ovarian cyst or ovary, comes with risks of infection, bleeding, tissue damage and allergic reactions to anaesthesia. 

If your cyst has grown so big that your entire ovary needs to be removed, this will affect your fertility. If both ovaries need to be removed, this will bring on early menopause. 

Do ovarian cysts recur?

Around 10–15% of ovarian cysts grow back after removal. New ovarian cysts can also develop; however, taking the combined oral contraceptive pill can help prevent new cysts from forming.