Ovarian cysts are common fluid-filled sacs that develop on or within the ovaries. The speed at which an ovarian cyst grows is highly variable and depends entirely on its underlying nature. Growth rates and the potential for resolution are determined by the cyst’s type—whether it is a temporary, hormone-driven structure or a persistent, abnormal tissue growth. Understanding this difference is fundamental to assessing its rate of change.
The Rapid Cycle of Functional Cysts
The most frequent type of ovarian cyst is the functional cyst, a normal byproduct of the menstrual cycle with rapid growth. These cysts, including follicular and corpus luteum cysts, form and resolve within weeks. A follicular cyst develops when the follicle fails to release its egg and accumulates fluid instead of dissolving.
This type of cyst typically reaches two to three centimeters in diameter within days or a few weeks. Growth is driven by hormonal signals, peaking within about one month before the structure begins to shrink spontaneously. Most functional cysts disappear entirely within one to three menstrual cycles without medical intervention, reflecting a rapid, temporary cycle.
Growth Patterns of Persistent Pathological Cysts
Pathological cysts are not related to the normal menstrual cycle and exhibit slow, continuous growth. These cysts, such as dermoid cysts, endometriomas, and cystadenomas, do not resolve on their own and require medical monitoring. Their expansion is measured over months or years, contrasting sharply with the weeks-long timeline of functional cysts.
Dermoid cysts (mature cystic teratomas) are known for their particularly slow rate of expansion, averaging approximately 1.8 millimeters per year in premenopausal women. Endometriomas (chocolate cysts) grow gradually as displaced endometrial-like tissue accumulates within the ovary with each menstrual cycle, expanding by only a few millimeters annually. Cystadenomas, which develop from the surface tissue of the ovary, also show a slow growth trajectory, with some types averaging a rate of about 0.65 centimeters per year.
Hormonal and Biological Factors Influencing Growth Speed
The speed of a cyst is largely dictated by its classification, but various biological factors influence its growth trajectory. Hormonal shifts are the primary driver; for example, fertility treatments involving gonadotropins can accelerate ovarian activity and lead to the development of numerous cysts. Pregnancy can also cause the formation of theca lutein cysts due to high levels of human chorionic gonadotropin (hCG) hormone.
The patient’s age significantly influences growth and risk profile. Rapid growth of functional cysts is common in pre-menopausal women because they rely on the ovulatory cycle. Conversely, new cyst growth in post-menopausal women requires prompt evaluation, as the lack of normal hormonal cycling suggests the cyst is less likely to be a benign functional type. Underlying conditions also affect growth: endometriosis drives the slow expansion of endometriomas, and the hormonal environment of Polycystic Ovary Syndrome (PCOS) results in multiple small, persistent follicles.
When Rapid or Sustained Growth Signals Concern
While most cysts are benign, a growth pattern that is both rapid and sustained can signal a more complex issue. Cysts that are malignant or borderline tumors often exhibit accelerated, continuous growth, sometimes doubling in size over weeks or months. This quick proliferation of abnormal cells is a clinical red flag that prompts immediate further investigation.
Rapid expansion, regardless of the cyst type, can precipitate acute complications. A sudden increase in size can lead to ovarian torsion, where the cyst’s weight causes the ovary to twist, cutting off its blood supply and resulting in severe pelvic pain. Rupture is another possibility, occurring when a rapidly expanding cyst bursts, causing acute pain and potential internal bleeding. Any noticeable, sudden, or sustained acceleration in cyst growth requires prompt medical evaluation.