How Common Are Ovarian Cysts?

Ovarian cysts are very common. Most women will have at least one at some point during their reproductive years. The vast majority are harmless, cause no symptoms, and go away on their own without treatment. While the exact number varies by age and how cysts are detected, studies consistently show that most premenopausal women develop them regularly as a normal part of the menstrual cycle.

What Exactly Is an Ovarian Cyst?

An ovarian cyst is a fluid-filled sac that forms on or inside an ovary. Think of it like a small blister filled with liquid. Most are tiny, but some can grow large enough to cause noticeable symptoms.

There are two main types. The most common are functional cysts, which form during a normal menstrual cycle. These are not disease. They are simply a follicle that grew, released an egg, or failed to release an egg and then filled with fluid. The other type is a pathologic cyst, which forms from abnormal cell growth. These are less common and include conditions like dermoid cysts, cystadenomas, and cysts related to endometriosis.

Functional cysts are the reason ovarian cysts are so common. They are a normal byproduct of ovulation. When your cycle works as it should, these cysts form, mature, and dissolve without you ever knowing they were there.

How Common Are Ovarian Cysts During the Menstrual Years?

Functional cysts occur in nearly every ovulating woman at some point. Ultrasound studies have found that up to 15-20% of premenopausal women have a visible ovarian cyst at any given time. Over a full year, that number climbs much higher because new cysts form with each cycle.

Age matters. These cysts are most frequent in women in their 20s, 30s, and early 40s — the years when ovulation is regular and predictable. After menopause, functional cysts stop forming because ovulation stops. If a postmenopausal woman has an ovarian cyst, it is not functional and needs closer evaluation.

Most of these cysts are small, often under 2-3 centimeters. Many are found completely by accident during a pelvic ultrasound done for another reason, like a routine exam or a pregnancy check.

Do Ovarian Cysts Cause Symptoms?

Most ovarian cysts cause no symptoms at all. This is why so many go undetected. A woman can have a cyst form and resolve every single month and never know it.

When symptoms do occur, they are usually mild. Common complaints include a dull ache or pressure on one side of the lower belly, bloating, or a sensation of fullness. Some women feel a sharp pain during ovulation when the cyst ruptures or the follicle releases its egg. This is called mittelschmerz and is completely normal.

Larger cysts can cause more noticeable symptoms. These include pelvic pain that lasts for days, pain during sex, or changes in your period. If a cyst twists the ovary — a condition called ovarian torsion — the pain is sudden, severe, and requires emergency care. This is rare, but it is a real risk with larger cysts.

How Often Do Ovarian Cysts Become Dangerous?

Serious complications are uncommon. The two main concerns are rupture and ovarian torsion.

A ruptured cyst causes sudden pain as fluid spills into the pelvic cavity. Most ruptures are harmless and the pain fades within hours. In rare cases, a cyst bleeds heavily when it ruptures, causing internal bleeding that requires medical attention. If you have sudden severe pain with dizziness, fainting, or shoulder pain, seek emergency care.

Ovarian torsion happens when a cyst makes the ovary heavy enough to twist on its own blood supply. This cuts off blood flow and causes intense pain. It is a surgical emergency. If treated quickly, the ovary can usually be saved. If not, the ovary may be lost.

Cancer is the concern most women worry about, but the risk is low. The chance that an ovarian cyst is malignant is less than 1% in premenopausal women. After menopause, the risk is higher but still under 10% for most cyst types. Doctors use ultrasound features, blood tests, and size to determine which cysts need follow-up and which can be left alone.

How Are Ovarian Cysts Diagnosed?

Most cysts are found during a pelvic exam or an ultrasound. A pelvic exam can feel a large cyst as a mass near the ovary, but it cannot see small ones. A transvaginal ultrasound is the standard way to confirm a cyst and describe its features.

Ultrasound tells the doctor several important things. It shows the size, shape, and whether the cyst is filled with clear fluid or has solid areas. Simple cysts — thin-walled, fluid-filled, with no solid parts — are almost always benign. Complex cysts with solid components or irregular borders need more investigation.

Blood tests are sometimes used. The CA-125 test measures a protein that can be elevated in ovarian cancer. But it is not a reliable screening test. Many benign conditions, including endometriosis, fibroids, and even normal menstruation, can raise CA-125 levels. It is most useful in postmenopausal women or when ultrasound features are concerning.

Do Ovarian Cysts Need Treatment?

In most cases, no treatment is needed. Functional cysts typically resolve within one to three menstrual cycles. Your doctor may simply recommend a follow-up ultrasound in six to eight weeks to confirm the cyst has shrunk or disappeared.

Birth control pills are sometimes prescribed to prevent new cysts from forming. They work by stopping ovulation, which stops functional cysts from developing. They do not shrink existing cysts faster, but they do reduce the number of new ones. Some clinicians recommend them for women who get painful cysts repeatedly.

Surgery is reserved for specific situations. These include cysts that are large — generally over 5-10 centimeters — cysts that persist for several cycles, cysts that cause significant pain, or cysts with suspicious features on ultrasound. The surgery is usually laparoscopic, meaning small incisions and a quick recovery. In many cases, only the cyst is removed and the ovary is preserved.

What About Ovarian Cysts During Pregnancy?

Ovarian cysts are common during pregnancy. Many are functional cysts that formed before conception and simply persist. Others are related to the corpus luteum, the structure that produces progesterone in early pregnancy.

Most pregnancy-associated cysts are harmless and resolve on their own by the second trimester. If a cyst is large or persists, your doctor may monitor it with ultrasound. Surgery during pregnancy is avoided unless the cyst causes pain, twists, or appears suspicious. In those rare cases, surgery can be performed safely, but it is only done when the benefit clearly outweighs the risk.

When Should You See a Doctor?

Most cysts need no medical attention. But certain symptoms warrant a call to your doctor. Sudden severe pelvic pain, pain with fever, dizziness, or fainting are red flags. Pain that does not go away or gets worse over days also deserves evaluation.

If you have not had a period in a year and an ultrasound shows a cyst, that cyst needs follow-up. Postmenopausal cysts are not functional and require a plan for monitoring or removal. The same applies to cysts that grow on repeat ultrasound or have solid components.

Routine gynecologic care is the best way to catch problems early. Pelvic exams and ultrasounds are not perfect, but they are the tools we have. If you have concerns about ovarian cysts, talk to your gynecologist. They can explain what your specific ultrasound findings mean and what follow-up is right for you.