An ovarian mass is any growth on or within an ovary, ranging from a harmless fluid-filled cyst to a solid tumor. The vast majority are benign. When a mass is discovered, usually during a routine pelvic exam or ultrasound, the immediate goal is figuring out what type it is, how large it is, and whether it shows any features that warrant closer attention or removal.
How Ovarian Masses Are Classified
The term “ovarian mass” is broad on purpose. It covers anything from a simple cyst (a thin-walled sac of fluid) to a solid growth made of connective tissue, and everything in between. Doctors typically sort these growths into three categories based on their internal structure: cystic (fluid-filled), solid, or mixed (containing both fluid and solid components). A mass that is entirely fluid-filled is far more likely to be benign. One that is partially or completely solid gets more scrutiny because solid components raise the possibility of cancer.
Functional cysts are the most common type and arguably the least concerning. They form naturally during the menstrual cycle when a follicle either doesn’t release its egg or doesn’t shrink back down afterward. These tend to be small and typically resolve on their own within two to three menstrual cycles without any treatment.
Common Benign Types
Dermoid cysts are one of the more unusual growths. They develop from cells that can produce many tissue types, so they sometimes contain hair, teeth, skin, or fatty material. Despite sounding alarming, dermoid cysts account for 10 to 20% of all ovarian tumors and are almost always noncancerous. They do tend to grow slowly over time, which is why they’re often eventually removed.
Endometriomas form when tissue similar to the uterine lining grows on or inside the ovary. These are sometimes called “chocolate cysts” because they contain old, dark blood. They affect 25 to 35% of people with endometriosis and can cause significant pelvic pain, especially during menstruation.
Cystadenomas are fluid-filled growths that develop from the surface of the ovary. They come in two main varieties: serous (filled with thin, watery fluid) and mucinous (filled with thicker, gel-like fluid). Cystadenomas tend to grow larger than other benign ovarian masses and sometimes reach considerable sizes before being detected.
Fibromas are solid masses made of connective tissue. Because they are entirely solid, they can initially look more suspicious on imaging, but they are benign.
Symptoms to Recognize
Many ovarian masses cause no symptoms at all, especially when they’re small. They’re often found incidentally during an ultrasound done for another reason entirely. When symptoms do appear, they tend to develop gradually as the mass grows and begins pressing on nearby structures.
The most commonly reported symptoms are bloating, pelvic or lower abdominal pain, feeling full quickly when eating, and urinary changes like needing to urinate more often or more urgently. These symptoms overlap heavily with everyday digestive complaints, which is one reason ovarian masses can go unnoticed for a long time. Persistent symptoms lasting more than a few weeks, particularly bloating and pelvic pressure that don’t come and go with your cycle, are worth investigating.
How Doctors Evaluate a Mass
Transvaginal ultrasound is the first-line imaging tool. It shows the size of the mass, whether it’s cystic or solid, and whether it has features like internal walls (septations), small finger-like projections, or significant blood flow. These details matter because they help predict whether the mass is likely benign or potentially malignant.
Researchers developed a practical scoring system using five features that suggest a benign mass and five that suggest a malignant one. Benign indicators include a simple single-chamber cyst, no detectable blood flow, and the presence of acoustic shadows (a pattern typical of dermoid cysts or fibromas). Malignant indicators include an irregular solid mass, fluid buildup in the abdomen, four or more small projections inside the cyst, and heavy blood flow visible on Doppler imaging. When only benign features are present, the mass is classified as likely benign. When only concerning features show up, it’s flagged for further evaluation. Sometimes features from both categories appear, and additional workup is needed.
Blood Tests
CA-125 is a protein that can be elevated in ovarian cancer, and it’s frequently checked when a mass is found. The standard threshold is 35 units per milliliter. But this test has real limitations. About 20% of ovarian cancers don’t produce elevated CA-125 at all. And many benign conditions raise it, including endometriosis, menstruation, anovulatory cycles, and even a higher body mass index. In one study, 80% of people with elevated CA-125 levels did not have ovarian cancer.
Because of this high false-positive rate, the American College of Obstetrics and Gynecology recommends using a higher cutoff of 200 units per milliliter for premenopausal women with pelvic masses. Among asymptomatic women screened at the standard 35 threshold, only about 1 in 100 positive results actually corresponds to cancer. CA-125 is more useful for tracking a known cancer’s response to treatment than for screening on its own.
When a Mass Might Be Cancer
The risk of malignancy depends heavily on age and menopausal status. Among epithelial ovarian cancers, which are the most common type, 58% are diagnosed after menopause and 42% before. The median age at diagnosis is 53. That said, certain subtypes skew younger. Germ cell tumors have a median diagnosis age of just 23, with 95% occurring before menopause. Sex-cord tumors have a median age of 44.
Mucinous carcinomas also behave differently from most epithelial cancers. About 77% are diagnosed before menopause, while only 23% occur afterward. The more common serous, endometrioid, and clear-cell subtypes follow the expected pattern, with roughly 60% diagnosed after menopause.
A mass that is entirely cystic, thin-walled, and under 10 cm has a very low probability of being malignant, even in postmenopausal patients. The concern rises with solid components, irregular borders, or rapid growth.
Size Thresholds and Monitoring
Not every ovarian mass needs surgery. Current guidelines from the American College of Obstetrics and Gynecology state that simple cysts up to 10 cm in diameter on ultrasound are likely benign and can be safely monitored with repeat imaging, even in postmenopausal patients.
For premenopausal women, the practical breakdown works like this: simple cysts under 5 cm usually resolve within two to three menstrual cycles and need no further workup. Cysts between 5 and 7 cm should be rechecked with ultrasound yearly. Cysts larger than 7 cm generally need advanced imaging like MRI or surgical evaluation. At that point, referral to a gynecologist is appropriate if you’re not already seeing one.
Ovarian Torsion Risk
One complication that requires emergency attention is ovarian torsion, where the ovary twists on its blood supply. This causes sudden, severe pelvic pain often accompanied by nausea and vomiting. Masses between 6 and 8 cm carry the highest torsion risk. In pregnant patients with known ovarian masses, about 15% experienced torsion, and masses in that 6 to 8 cm range had a torsion rate of 22% compared to about 9% for other sizes. This is one reason mid-sized masses are sometimes removed even when they appear benign.
Surgical Options
When surgery is needed, the two main approaches are cystectomy (removing only the mass while preserving the ovary) and salpingo-oophorectomy (removing the ovary and its fallopian tube). The choice depends on the type of mass, how suspicious it looks, and whether you want to preserve fertility.
Cystectomy preserves more ovarian tissue, which matters for future egg production. In studies of borderline ovarian tumors, patients who had cystectomy had higher pregnancy rates afterward compared to those who had an ovary removed. However, cystectomy also carries a higher recurrence rate, up to 9.3%, with a shorter interval before the mass comes back (around 23 months on average). Removing the ovary and tube significantly reduces recurrence risk without appearing to lower overall pregnancy chances, since the remaining ovary can still function normally. For this reason, removing one ovary with its tube is generally the preferred approach when a borderline tumor is found and fertility is still desired.
For clearly benign masses in younger patients, cystectomy alone is often sufficient. In older patients or those past menopause, removing the ovary is more common since preserving ovarian tissue is less of a priority.