What is an ovarian cyst?

An ovarian cyst is a fluid-filled sac that forms on or inside an ovary. The ovaries are 2 small, oval-shaped organs in the lower part of the belly (abdomen). About once a month, 1 of the ovaries releases an egg. The ovaries also make the hormones estrogen and progesterone. These play roles in pregnancy, the menstrual cycle, and breast growth.

There are different kinds of ovarian cysts. They can occur for various reasons, and they may need different treatments. A cyst can vary in size from half an inch to 4 inches, and sometimes be even much larger.

Ovarian cysts are very common in people of childbearing age, but uncommon after menopause. Children can also get them, but this is less common.

What causes an ovarian cyst?

Different types of ovarian cysts have different causes. The most common type of ovarian cyst is known as a functional cyst. Functional ovarian cysts only happen in people who have started their menstrual cycles, but haven’t gone through menopause. There are 2 types of functional cysts:

  • Follicular cyst. This cyst happens when an egg isn’t released. It keeps growing inside the ovary. 
  • Corpus luteum cyst. This type of cyst occurs when the sac around the egg doesn’t dissolve after the egg is released.

Other types and causes of cysts include:

  • Endometrioma. This cyst is filled with old blood and tissue that resembles the lining of the uterus. They are often called chocolate cysts because of the dark color of the fluid within them. They can happen in people with endometriosis. 
  • Dermoid. This cyst develops from ovarian cells and eggs. They may have hair, skin, teeth, bone, or fat in them. These cysts are common in people of childbearing age.

Cysts can also be caused by:

  • Polycystic ovary syndrome (PCOS), a condition that causes multiple cysts on the ovaries
  • Pregnancy
  • Severe pelvic infection such as chlamydia. This type of cyst may be called an abscess.
  • Noncancerous growths
  • Cancer (rare)

Who is at risk of having an ovarian cyst?

Certain things may increase your risk of having an ovarian cyst. 

  • Endometriosis
  • Polycystic ovarian syndrome (PCOS)
  • Pregnancy
  • Using fertility medicines such as clomiphene

What are the symptoms of an ovarian cyst?

Many people don’t have any symptoms from the cyst. If there are symptoms, the most common is pain or pressure in your lower belly on the side of the cyst. This pain may be dull or sharp, and it may come and go. A cyst that breaks open and bleeds may lead to sudden, sharp pain. This is called a hemorrhagic cyst.

Other symptoms of an ovarian cyst can include:

  • Pain in the low back or thighs
  • Trouble emptying your bladder completely
  • Pain during sex
  • Weight gain
  • Pain during your period
  • Breast tenderness
  • Abnormal vaginal bleeding (rare)

How is an ovarian cyst diagnosed?

Your primary care provider, an obstetrics and gynecology (OB/GYN) doctor, or certified nurse midwife may diagnose the condition. Your healthcare provider will ask about your health history and your symptoms. You will also have a physical exam. This will likely include a pelvic exam. During the pelvic exam, your healthcare provider may feel the swelling on your ovary. In people with no symptoms, this is often the first sign of a cyst.

If your healthcare provider thinks you may have an ovarian cyst, you may need tests. These can help your healthcare provider learn the type of cyst. Tests can also help rule out other problems, such as an ectopic pregnancy. The tests may include:

  • Ultrasound. This test uses sound waves to view the size, shape, and location of the cyst. The test can also show if the growth is solid or filled with fluid.
  • MRI. This uses large magnets and a computer to create a detailed picture of the area.
  • Pregnancy test. This is done to check if pregnancy may be the cause of the cyst.
  • Blood tests. These check for hormone problems and cancer. They also check if the cyst is bleeding.
  • Biopsy. This is a test where a tiny piece of the ovary is taken. The piece is examined in a lab for cancer cells. This may be done if an ultrasound shows a certain type of growth on the ovary. Biopsy of the ovary is usually not done if cancer is suspected. 

How is an ovarian cyst treated?

Treatment for an ovarian cyst will depend on the type of cyst, your age, and your general health. In most cases, no treatment is needed. You may be told to watch your symptoms over time. An ovarian cyst will often go away with no treatment in a few weeks or months.

In some cases, you may need to have follow-up ultrasound tests. These are to check if your cyst has gone away or is not growing. You may not need any other treatment.

If your ultrasound or blood tests show signs of cancer, your provider may advise surgery. This is done to remove part or all of your ovary. Your provider might also advise surgery if:

  • Your cyst causes ongoing pressure or pain
  • Your cyst seems to be growing
  • You have a very large cyst
  • You have endometriosis and want the cyst removed to help with fertility

Can an ovarian cyst be prevented?

If you have hormone issues, your healthcare provider may advise taking birth control pills. These may help prevent ovarian cysts. Taking antibiotics for a pelvic infection may also prevent a cyst.

What are possible complications of an ovarian cyst?

An ovarian cyst can sometimes break open (rupture). This may not cause any symptoms. Or it may cause sudden, sharp pain in the lower belly. A ruptured cyst can cause a lot of blood and fluid loss. This can lead to low blood pressure. In some cases, surgery may be needed.

In rare cases, an ovarian cyst can also cause twisting (torsion) of the fallopian tube. This can block normal blood supply to the ovary. This can lead to sudden pain and sometimes nausea and vomiting. It may need emergency surgery.

How to manage an ovarian cyst

Work with your healthcare provider to find a treatment plan that makes sense for you. Keep all of your follow-up appointments. Tell your provider right away if you have sudden belly pain or other severe symptoms. These may be caused by a ruptured ovarian cyst.

Key points about ovarian cysts

  • An ovarian cyst is a fluid-filled sac that forms in or on 1 of your ovaries.
  • Most ovarian cysts are functional cysts. These are linked to ovulation. They often go away with no treatment.
  • Only a small number of ovarian cysts are caused by cancer.
  • PCOS, endometriosis, and pelvic infection are some of the other causes of ovarian cysts.
  • A cyst may cause symptoms, such as abdominal pain. Or it may cause no symptoms.
  • You may need tests to help diagnose your cyst. These may include an ultrasound and blood tests.
  • You may need no treatment for the cyst. Or you may need surgery.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.
  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
  • Ask if your condition can be treated in other ways.
  • Know why a test or procedure is recommended and what the results could mean.
  • Know what to expect if you do not take the medicine or have the test or procedure.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.