Ovarian cysts after menopause are surprisingly common, showing up in about 14% of women over 55 on their first ultrasound screening. Unlike the functional cysts that form during reproductive years (which are tied to ovulation), postmenopausal cysts develop through different mechanisms. The reassuring news: the vast majority are benign, and simple cysts do not increase the risk of ovarian cancer.
Why Cysts Still Form After Ovulation Stops
During your reproductive years, most ovarian cysts are “functional,” meaning they form as a normal byproduct of your monthly cycle. A follicle releases an egg, and sometimes the fluid-filled sac doesn’t dissolve on schedule. After menopause, ovulation stops entirely, so these functional cysts no longer occur.
The cysts that do form after menopause are called pathological cysts. They develop from abnormal cell growth rather than from the menstrual cycle. Specifically, they arise from two sources: the cells that would have been used to create eggs, or the cells covering the outer surface of the ovary. These cells can still multiply and form fluid-filled pockets regardless of hormonal cycling. About 8% of postmenopausal women develop a new simple cyst each year, and most of these either stay stable or resolve on their own by the next annual check.
Types of Postmenopausal Cysts
Simple Cysts
These are thin-walled, fluid-filled sacs with no solid components or internal divisions. They’re the most common type found after menopause and carry the lowest risk. A simple cyst that measures 3 centimeters or smaller typically doesn’t even require follow-up, according to guidelines from the Royal College of Obstetricians and Gynaecologists.
Endometriomas
Women who had endometriosis before menopause can still develop ovarian cysts called endometriomas. Endometriosis causes tissue similar to the uterine lining to grow outside the uterus, and when it involves the ovaries, cysts form. Menopause often reduces endometriosis-related pain over time because estrogen levels drop. However, women taking estrogen therapy may continue to experience symptoms and cyst growth.
Paraovarian Cysts
These form near the ovary rather than on it, developing when parts of the broad ligament (the tissue that supports the ovary and fallopian tubes) grow into a sac and fill with fluid. While they’re more commonly diagnosed during reproductive years, they can appear at any age. A specific subtype, called hydatid cysts of Morgagni, forms on the fingerlike ends of the fallopian tubes.
Cysts With Complex Features
Some cysts contain solid components, internal walls (septations), or blood flow visible on ultrasound. These complex features don’t automatically mean cancer, but they do warrant closer evaluation. Ultrasound categorization systems classify cysts into tiers: those with no solid components, those with a small solid area under 1 centimeter, and those with multiple or large solid components. Higher-tier cysts get more aggressive follow-up.
The Role of Hormone Therapy
Hormone replacement therapy (HRT) is one external factor that can influence what happens on the ovaries after menopause. By reintroducing estrogen, sometimes combined with progesterone, HRT can stimulate ovarian tissue that would otherwise be dormant. Research on HRT has focused more on ovarian cancer risk than on benign cyst formation specifically, but the hormonal mechanism is relevant: estrogen promotes cell growth in reproductive tissues, which can contribute to cyst development.
How Dangerous Is a Postmenopausal Cyst?
The cancer concern is what brings most readers to this topic, and the data is largely reassuring. In a large community-based study of women over 50 with an ovarian mass, only 0.5% were ultimately diagnosed with invasive ovarian cancer. Among those whose cysts appeared stable on a follow-up ultrasound at least six weeks later, the risk dropped to 0.27%. And after a full year of stability on imaging, no cancer cases were observed at all.
Cysts that changed between ultrasounds told a different story. Women whose masses were “unstable,” meaning they grew, developed new features, or otherwise changed, had a cancer risk roughly six times higher at 1.73%. This is why follow-up imaging matters so much. A cyst that stays the same over time is overwhelmingly likely to be harmless.
How Cysts Are Evaluated
Transvaginal ultrasound is the first tool used to characterize any ovarian cyst. The imaging reveals size, whether the cyst is simple or complex, and whether it has features like solid areas or blood flow. These details drive the next steps far more than the cyst’s mere existence.
A blood test measuring CA-125 levels is often ordered alongside imaging. CA-125 is a protein that can be elevated in ovarian cancer, with the normal reference range falling below 35 units per milliliter. This test is more useful in postmenopausal women than in younger women because many benign conditions that raise CA-125 during reproductive years (endometriosis, fibroids, even menstruation) are no longer in play. Still, CA-125 alone isn’t definitive. About 80% of women with epithelial ovarian cancer have elevated levels, which means 20% don’t. Combining CA-125 with a second protein marker pushes diagnostic accuracy to roughly 94% sensitivity and 88% specificity.
Size Thresholds That Guide Management
Clinical guidelines use specific size cutoffs to determine how a postmenopausal cyst is managed:
- 3 cm or smaller: A simple, one-sided cyst at this size has a very low malignancy risk and generally doesn’t need follow-up.
- Between 3 and 5 cm: If the cyst is simple, one-sided, has a single chamber, and CA-125 is normal, it can be monitored with a repeat evaluation in four to six months.
- Larger than 5 cm: Cysts above this threshold are more likely to be referred for surgical evaluation, especially if they have complex features, cause symptoms, or appear on both ovaries.
Features that push toward surgery regardless of size include symptoms like pain or pressure, complex internal structure, cysts on both ovaries, or multiple internal chambers.
Symptoms to Be Aware Of
Most postmenopausal cysts cause no symptoms at all and are discovered incidentally during imaging for something else. When symptoms do occur, they typically include a dull ache or sharp pain on one side of the lower abdomen, a sense of fullness or pressure in the belly, or bloating.
Rare but serious complications include ovarian torsion, where the ovary twists on its supporting tissue, cutting off blood supply. This causes sudden, severe pelvic pain along with nausea and vomiting. A ruptured cyst can also cause intense pain and internal bleeding. Both situations produce symptoms that are hard to ignore: cold or clammy skin, rapid breathing, lightheadedness, or weakness alongside severe pelvic pain. These are emergencies.