Ovarian cysts are fluid-filled sacs that develop on or inside the ovaries. They are extremely common, especially during the reproductive years, and the vast majority resolve on their own without treatment. Most cause no symptoms at all and are discovered incidentally during a routine ultrasound or pelvic exam.
How Ovarian Cysts Form
The most common ovarian cysts are called functional cysts, and they’re a normal byproduct of your menstrual cycle. Every month, your ovary grows a small fluid-filled structure called a follicle, which houses a maturing egg. When everything goes as planned, the follicle ruptures to release the egg during ovulation, then transforms into a temporary hormone-producing structure called the corpus luteum, which eventually dissolves.
Functional cysts happen when this process doesn’t go quite right. A follicular cyst forms when the follicle fails to rupture and release its egg, so it keeps growing instead. A corpus luteum cyst forms when the corpus luteum doesn’t dissolve as it should and instead fills with fluid. Corpus luteum cysts can produce excess progesterone and typically take up to three months to disappear on their own. Both types are harmless in the vast majority of cases and are actually a sign that your reproductive system is working.
Types Beyond Functional Cysts
Not all ovarian cysts are tied to your menstrual cycle. Several other types develop for different reasons and behave differently.
Dermoid cysts (also called mature cystic teratomas) are among the most unusual. They form when fully developed tissue collects inside the ovary, and they can contain skin, hair, teeth, nerves, and even brain tissue. Sweat glands inside the cyst secrete an oily fluid that causes it to grow over time. Despite their strange contents, dermoid cysts are benign in the vast majority of cases, becoming cancerous in less than 2% of instances.
Endometriomas develop in people with endometriosis, a condition where tissue similar to the uterine lining grows outside the uterus. These cysts fill with old, dark blood, which is why they’re sometimes called “chocolate cysts.” They can be painful and are linked to fertility problems.
Cystadenomas are growths that arise from the outer surface of the ovary. They can grow quite large and may need treatment for that reason, but they’re typically benign.
Polycystic ovary syndrome (PCOS) produces a different pattern: multiple small follicular cysts on enlarged ovaries, along with irregular periods and hormonal imbalances.
What Ovarian Cysts Feel Like
Most ovarian cysts produce zero symptoms. You can have one right now and never know it. When a cyst does grow large enough to cause problems, the most common signs are:
- Pelvic pain that comes and goes, ranging from a dull ache to a sharp pain on one side below the bellybutton
- A feeling of fullness, pressure, or heaviness in the abdomen
- Bloating
These symptoms overlap with many other conditions, which is why cysts are often identified through imaging rather than symptoms alone.
When a Cyst Becomes an Emergency
Two complications can turn an otherwise harmless cyst into a medical emergency: rupture and torsion.
A ruptured cyst bursts open, which can cause sudden, severe pelvic pain and internal bleeding. In many cases, your body absorbs the leaked contents without lasting harm. But significant ruptures with heavy bleeding need immediate attention.
Ovarian torsion happens when a cyst grows large enough to cause the ovary to twist on itself, cutting off its blood supply. The risk of torsion rises significantly once a cyst reaches 5 to 6 centimeters. Torsion causes sudden, intense pelvic pain along with nausea and vomiting, and it requires emergency surgery to save the ovary. Without treatment, the ovary can die from lack of blood flow.
Seek immediate care if you experience sudden severe abdominal or pelvic pain, pain accompanied by fever or vomiting, or signs of shock like cold and clammy skin, rapid breathing, or lightheadedness.
How Cysts Are Diagnosed
Ultrasound is the primary tool for identifying and evaluating ovarian cysts. Doctors look at specific features to determine whether a cyst is likely benign or potentially concerning. A simple, single-chambered cyst with thin walls and no internal blood flow is almost always benign. Features that raise more concern include irregular solid areas, multiple internal structures, strong blood flow within the cyst, and large size (particularly over 10 centimeters).
A blood test measuring a protein called CA-125 is sometimes used as part of the evaluation, particularly in postmenopausal women. However, CA-125 is an imperfect tool. It’s elevated in only about 20% of ovarian cancers, and it can also be raised by completely benign conditions. Combined with ultrasound, its positive predictive value for ovarian cancer is around 40%, meaning it still produces many false alarms.
Cancer Risk in Perspective
The question most people really want answered is whether their cyst could be cancer. For premenopausal women, the odds are very low. Functional cysts, dermoid cysts, and cystadenomas are overwhelmingly benign. The picture shifts somewhat after menopause. About 13% of postmenopausal women have ovarian cysts, and these require more careful monitoring because they can occasionally be precursors to ovarian cancer. Age, cyst size, and imaging characteristics all factor into how aggressively a cyst is evaluated.
Treatment and Monitoring
For most functional cysts, the standard approach is watchful waiting. Your doctor will likely recommend a follow-up ultrasound in 6 to 8 weeks to confirm the cyst has resolved. Most do.
Hormonal birth control (like the pill) can prevent new functional cysts from forming by suppressing ovulation. This is useful if you get recurrent cysts. One important distinction: birth control prevents future cysts but will not shrink a cyst you already have.
Surgery becomes part of the conversation when a cyst is large, persistent, growing, causing significant symptoms, or has worrisome features on imaging. Cysts over 5 to 6 centimeters carry a higher torsion risk and are monitored more closely. When surgery is needed, cysts under roughly 10 to 12 centimeters can typically be removed through minimally invasive laparoscopic surgery. Larger cysts may require a larger incision.
Effects on Fertility
If you’re trying to conceive, the type of cyst matters far more than whether you have one. Functional cysts, dermoid cysts, and cystadenomas do not affect fertility. In fact, getting functional cysts means the key processes leading to conception are taking place normally.
The types that can interfere with fertility are endometriomas and cysts from PCOS. Endometriomas are associated with difficulty becoming pregnant, though many people with endometriosis do conceive. PCOS can lead to less frequent ovulation, which plays a role in fertility issues for some people. Both conditions have well-established treatment paths for those trying to get pregnant.