Ovarian Cysts: What They Are, When to Worry, and When Not To

Finding out you have an ovarian cyst, whether through an incidental ultrasound or after pelvic pain sends you for imaging, is an anxiety-producing experience for most women. The words "cyst" and "ovary" in the same sentence suggest cancer to many people, which is understandable but in the vast majority of cases is not the relevant concern. Most ovarian cysts in women of reproductive age are functional: they form as part of the normal menstrual cycle, are filled with fluid, produce no lasting harm, and resolve on their own within weeks to months. The cases that require more than watchful waiting are identifiable by specific features. Understanding what distinguishes them makes the clinical picture significantly less frightening.

What Ovarian Cysts Are

An ovarian cyst is a fluid-filled sac that forms on or within an ovary. The ovaries are active structures that form and rupture follicles each menstrual cycle as part of normal ovulation. This process naturally produces cysts. The classification of ovarian cysts that matters clinically is functional versus non-functional.

Functional Cysts

Functional cysts arise directly from the normal menstrual cycle mechanism and are by far the most common type. They include follicular cysts and corpus luteum cysts.

A follicular cyst forms when the dominant follicle, which normally ruptures at ovulation to release an egg, fails to rupture and continues to grow. It is filled with follicular fluid and can reach several centimeters in diameter. Most resolve within one to three menstrual cycles without any treatment. They are often asymptomatic and discovered incidentally on imaging done for another reason.

A corpus luteum cyst forms after a follicle ruptures and the resulting corpus luteum (which normally produces progesterone in the second half of the cycle) fills with fluid rather than degenerating as expected. Corpus luteum cysts may be somewhat more likely to cause symptoms, including pelvic pressure or mild pain, and can occasionally rupture or bleed. They also resolve spontaneously in most cases within a few weeks.

Both types of functional cysts are benign, hormone-responsive, and self-limiting. They are not a sign of cancer and do not require surgery in the absence of complications.

Non-Functional Cysts

Non-functional cysts are not products of the normal ovulatory cycle. They include several types with different clinical implications.

Dermoid cysts (also called mature cystic teratomas) are among the most common non-functional ovarian cysts in young women. They are classified as benign tumors that contain tissues derived from multiple cell layers, meaning they can contain hair, skin cells, fatty tissue, and occasionally teeth or cartilage. They tend to be slow-growing, are bilateral in roughly 10 to 15% of cases, and do not resolve on their own. Dermoid cysts larger than approximately 6 centimeters are generally recommended for surgical removal because of the risk of torsion (the ovary twisting on its pedicle, cutting off its blood supply), which is a surgical emergency.

Endometriomas are cysts that form when endometrial tissue (the tissue that normally lines the uterus) grows on the ovary. They are filled with old blood, producing the characteristic dark brown "chocolate cyst" appearance on imaging and at surgery. Endometriomas are a hallmark of endometriosis and do not resolve on their own. They are associated with pelvic pain, painful periods, and, in significant cases, reduced ovarian reserve and fertility impairment. Management depends on size, symptom severity, and fertility plans.

Cystadenomas are fluid-filled benign tumors that arise from the ovarian surface epithelium. They can grow large and tend to require surgical removal when they do. Serous cystadenomas are filled with watery fluid; mucinous cystadenomas are filled with thicker mucin-like fluid and can reach very large sizes.

How Ovarian Cysts Are Evaluated

Ultrasound is the primary tool for characterizing ovarian cysts. The features that matter most are: size, contents (simple fluid versus complex contents such as solid components, septations, or internal echoes), and in postmenopausal women, any complexity at all is viewed with higher concern than in premenopausal women.

Simple cysts, meaning thin-walled and filled with anechoic (clear) fluid, are almost always benign in women of reproductive age. They are typically managed with surveillance ultrasound and resolve spontaneously. The size threshold at which even simple cysts are recommended for surgical evaluation varies by guideline but is generally 10 centimeters, because of the risk of torsion at larger sizes.

Complex features, including thick walls, multiple septations, solid components, irregular borders, or internal blood flow on Doppler ultrasound, prompt more careful evaluation. Tumor markers including CA-125 may be ordered, though CA-125 is neither sensitive nor specific for ovarian cancer and can be elevated in many benign conditions including endometriosis, fibroids, and pelvic inflammatory disease.

In postmenopausal women, the threshold for concern is lower. Even small simple cysts warrant closer follow-up, though most are still benign. Complex features in postmenopausal women prompt expedited gynecologic oncology referral.

Symptoms

Most ovarian cysts cause no symptoms at all and are found incidentally. When symptoms occur, they typically include pelvic pressure, bloating, a sensation of fullness, or mild discomfort on the side of the cyst. Pain with intercourse can occur if the cyst is positioned such that penetration applies pressure to it.

Cyst rupture can cause sudden sharp pelvic pain. This is usually self-limiting and resolves within a few hours to days. A ruptured corpus luteum cyst can bleed into the abdomen. In most cases this resolves without intervention, but in some women (particularly those on anticoagulant medications) it can cause significant hemorrhage requiring surgical management. Sudden severe pelvic pain with hemodynamic instability warrants emergency evaluation.

Ovarian torsion, where the ovary (and sometimes the fallopian tube) twists on its ligamentous support, compromising blood supply, presents with sudden severe unilateral pelvic pain, often with nausea and vomiting. It is a surgical emergency. Torsion is more likely with larger cysts, particularly dermoid cysts and cystadenomas, which increase the ovary's weight and change its center of gravity. Any sudden, severe, one-sided pelvic pain should prompt same-day emergency evaluation to rule out torsion.

Treatment

Functional cysts are managed with watchful waiting and a repeat ultrasound in six to eight weeks to confirm resolution. No intervention is required in the absence of significant symptoms or complications. Hormonal contraceptives were historically prescribed to "suppress" functional cysts, but evidence does not support that they accelerate resolution of existing cysts. They may reduce the formation of new functional cysts in some individuals.

Surgical management is indicated for cysts with complex features warranting pathological assessment, cysts that do not resolve after adequate observation, cysts at high risk of or causing torsion, cysts with significant ongoing symptoms, and cysts in postmenopausal women with concerning characteristics. In younger women, the surgical approach is typically laparoscopic cystectomy, which removes the cyst while preserving the ovary and its function. Oophorectomy (removal of the ovary) is reserved for cases where the cyst has replaced the ovarian tissue entirely or where histological findings indicate malignancy.

Ovarian Cancer

The fear associated with ovarian cysts is primarily the fear of ovarian cancer. It is worth naming this directly: simple ovarian cysts in premenopausal women have an extremely low malignancy risk. Ovarian cancer is rare compared to the prevalence of benign ovarian cysts. The features that distinguish benign from potentially malignant cysts on imaging are specific and identifiable. Finding an ovarian cyst does not mean cancer is likely or even a significant concern in the absence of the high-risk features described above.

Risk factors for ovarian cancer include older age, personal or family history of ovarian or BRCA-related cancers, and endometriosis. Genetic counseling and testing for BRCA1/2 mutations is appropriate for individuals with a strong family history. Routine CA-125 screening in the general population is not recommended by any major guideline because it produces high false positive rates and leads to unnecessary surgery without improving survival outcomes.

When to See a Doctor

Seek urgent evaluation for sudden severe pelvic pain, which may indicate cyst rupture with hemorrhage or torsion. See a gynecologist if you have been told you have an ovarian cyst and have not received a follow-up plan, if your cyst-related symptoms are worsening, or if you have risk factors for ovarian cancer and want individualized guidance. A JourneyDoctors OB-GYN can review your imaging results, assess the features of your cyst, and advise on appropriate monitoring or referral.

Disclaimer: This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for diagnosis and treatment.

Frequently Asked Questions

Do ovarian cysts go away on their own?

Functional cysts, the large majority of ovarian cysts in premenopausal women, typically resolve within one to three menstrual cycles without any treatment. Non-functional cysts such as dermoid cysts, endometriomas, and cystadenomas do not resolve spontaneously and require monitoring and often surgical management.

Can an ovarian cyst affect fertility?

Most simple functional cysts do not affect fertility. Endometriomas can impair ovarian reserve and egg quality if large or if they have been present for a long time. Large cysts of any type can mechanically affect ovulation or fallopian tube function. If you are trying to conceive and have an ovarian cyst, discuss its potential impact with a reproductive endocrinologist.

Why do I keep getting ovarian cysts?

Recurrent functional cysts can occur in women with irregular cycles or those who are not ovulating predictably. PCOS is often associated with multiple small follicles rather than true cysts, though the terminology is sometimes confused. If you are having recurrent cysts, hormonal evaluation may be helpful to identify an underlying pattern.

How big is too big for an ovarian cyst?

Size guidance varies by cyst type and individual characteristics, but simple cysts larger than 10 centimeters are generally considered for surgical evaluation due to torsion risk, regardless of their benign appearance. Complex cysts warrant evaluation at smaller sizes. Your gynecologist can advise on appropriate thresholds based on your specific imaging findings.

Should I be worried about ovarian cancer if I have a cyst?

In most cases, no. Simple ovarian cysts in premenopausal women have a very low malignancy risk. Complex features on ultrasound prompt further evaluation to stratify risk. If your ultrasound shows only a simple thin-walled cyst and you are premenopausal with no other risk factors, the probability of malignancy is very low and should not be the default assumption.