Ovarian cysts are fluid-filled sacs that can form in or on your ovaries. Most ovarian cysts are benign (noncancerous), and are typically caused by hormonal changes, pregnancy, or conditions like endometriosis.

The most common type of ovarian cyst, known as a functional or ovulatory cyst, is completely normal. It develops every month when you ovulate. They aren’t usually harmful, have no symptoms, and typically go away on their own within a few weeks.

But this isn’t the only type of cyst that can develop in or on your ovaries. Some other types are a lot less common than the cysts that develop each month due to ovulation.

This article will look at the different types of ovarian cysts, the typical size of each, as well as potential treatment options.

There are different types of ovarian cysts, each with unique causes and characteristics. The size of an ovarian cyst can also vary depending on what type of cyst it is.

Size is also one of several factors that can help determine whether a cyst needs to be surgically removed. Generally speaking, surgery isn’t recommended for ovarian cysts unless they’re larger than 50 to 60 millimeters (mm) (about 2 to 2.4 inches) in size.

However, this guideline can vary. For instance, a simple cyst may be left alone until it’s 10 cm (4 inches) in size. And cancerous cysts may be removed when they’re much smaller.

Let’s look at each type of ovarian cyst in more detail as well as the typical size of each.

Functional cysts form when your menstrual cycle follows its normal pattern. In some cases, though, the cyst can continue growing. Two examples of functional cysts include the following:

  • Follicular. Follicular cysts form when a follicle, a small sac that stores an egg and produces estrogen, doesn’t release the egg during ovulation. Instead, the follicle continues growing, producing a follicular cyst.
  • Corpus luteum. Corpus luteum cysts can form when the empty follicle sac doesn’t shrink after ovulation. Instead, the sac becomes sealed off and starts to fill with fluid, leading to a corpus luteum cyst.

Most functional cysts are 2 to 5 centimeters (cm) (about 3/4 of an inch to 2 inches) in size. Ovulation happens when these cysts are around 2 to 3 cm in size. However, some may reach sizes of 8 to 12 cm (around 3 to 5 inches).

Dermoid cysts are also called teratomas. They can contain different types of tissue, such as skin, hair, and fat. Dermoid cysts are often asymptomatic, although they may cause symptoms and complications if they become large.

These cysts are actually a type of ovarian tumor. They’re almost always benign and are often present from birth. Dermoid cysts can grow during a woman’s reproductive years

These cysts often grow slowly, progressing at a rate of about 1.8 mm (about 0.07 inches) per year.

Dermoid cysts do have the potential to become large, though. Case studies have reported that some dermoid cysts can grow more rapidly, between 8 and 25 mm (0.3 to about 1 inch) per year.

In rare cases, giant dermoid cysts over 15 cm (about 6 inches) in diameter have been reported.

Cystadenomas are benign tumors that develop on the surface of your ovaries. They can be filled with a watery or mucus-like liquid.

When viewed using ultrasound, a cystadenoma often looks like a functional cyst. However, while functional cysts typically go away after several menstrual cycles, a cystadenoma will continue to get bigger.

Cystadenomas can also become quite large. While some can be on the smaller side, around 1 to 3 cm (roughly half an inch to 1 inch), some can grow up to 30 cm (almost a foot)!

Endometriomas form due to endometriosis. Endometriosis is a condition where the cells of the uterine lining grow outside of the uterus. This tissue can attach to the surface of your ovary and form a cyst.

It’s estimated that between 17 and 44 percent of women with endometriosis will have an endometrioma. These cysts are sometimes called chocolate cysts because they can contain thick, dark blood that gives them a brownish color.

Endometriomas are typically small, but like other cysts, they can come in a range of sizes.

Many times, ovarian cysts don’t have any symptoms. When symptoms are present, they can include:

  • pain on one side of your lower abdomen, which may be dull or sharp
  • a feeling of fullness or pressure in your abdomen
  • abdominal bloating or swelling

Other less common symptoms can include:

Complications from ovarian cysts are rare. Sometimes a cyst can break open (rupture), leading to pain or bleeding.

In other cases, the ovary can become twisted around surrounding tissues (torsion), potentially cutting off the blood supply to the ovary.

Be sure to seek prompt medical attention if you experience any of the following symptoms:

Not all ovarian cysts require treatment, and many go away on their own. Because of this, your doctor may recommend a period of watchful waiting to monitor your cyst to see if it goes away after one or two menstrual cycles.

If you experience discomfort from an ovarian cyst, your doctor may suggest over-the-counter (OTC) pain medications to help with pain relief. Examples include:

Sometimes, an ovarian cyst may require surgical removal. This may be necessary when a cyst:

  • is large or continues to grow
  • doesn’t go away on its own after several menstrual cycles
  • causes acute pain
  • appears abnormal or malignant (cancerous) via ultrasound

Surgical removal of ovarian cysts is often accomplished using minimally invasive methods like laparoscopy. However, more invasive open surgery may be necessary when a cyst is very large or cancer is suspected.

If you often get functional cysts, your doctor may prescribe a hormonal contraceptive for you. While this medication can help prevent new functional cysts from forming, it won’t shrink an existing cyst.

Most women have ovarian cysts at some point during their lifetime. In fact, functional ovarian cysts are a normal part of your menstrual cycle. These cysts typically don’t have any symptoms and usually go away within a few weeks.

Some other types of cysts, like dermoid cysts, cystadenomas, and endometriomas, are a lot less common. These cysts can continue to grow and become large in size.

Most cysts don’t need to be surgically removed. However, surgery may be recommended for cysts that are large, don’t go away on their own, or appear abnormal by ultrasound.