From the Guidelines
Small ovarian cysts, typically less than 3 cm in diameter, are considered a normal finding in many women, particularly in premenopausal women, as they are often functional cysts that resolve on their own without requiring treatment. These cysts, including follicular cysts and corpus luteum cysts, are a common occurrence during the normal menstrual cycle as follicles grow and release eggs 1. According to the American College of Radiology's Ovarian-Adnexal Reporting and Data System (O-RADS) committee, simple cysts up to 10 cm in diameter on transvaginal ultrasonography are likely to be benign and may be safely monitored using repeat imaging without surgical intervention, even in postmenopausal patients 1.
The risk of malignancy in simple cysts is extremely low, with studies suggesting that the risk is approximately 0.5% in premenopausal women and 1.5% in postmenopausal women 1. A recent meta-analysis by Parazzini et al found that the risk of malignancy in unilocular cysts removed surgically in premenopausal women was 0.6% 1. The American College of Obstetricians and Gynecologists recommends that simple cysts less than or equal to 5 cm in diameter in premenopausal patients do not require additional management, and those less than or equal to 3 cm should be considered physiologic 1.
Key points to consider when evaluating small ovarian cysts include:
- Cyst size: Simple cysts up to 10 cm in diameter are likely to be benign
- Menopausal status: Premenopausal women have a lower risk of malignancy than postmenopausal women
- Cyst characteristics: Simple cysts with a thin wall and no septations or solid components are more likely to be benign
- Symptoms: The presence of symptoms such as pelvic pain or irregular bleeding may warrant further evaluation
In general, small ovarian cysts can be safely monitored with routine imaging, and further evaluation is only necessary if the cyst is large, persists for multiple cycles, or causes symptoms. This approach prioritizes the patient's quality of life and minimizes the risk of unnecessary interventions, while also ensuring that any potential malignancies are detected and treated promptly 1.
From the Research
Prevalence of Small Ovarian Cysts
- Small ovarian cysts are a common finding in postmenopausal women, with a prevalence of 6.6% to 8.2% 2, 3, 4
- These cysts are often detected incidentally by high-resolution transvaginal ultrasound in asymptomatic women 2, 4
Natural History of Small Ovarian Cysts
- Many small ovarian cysts will resolve spontaneously, with resolution rates ranging from 23.28% to 46.30% 3, 4, 5
- Some cysts will persist unchanged, while others may increase in size or develop solid components 3, 4, 5
- The risk of malignant transformation is low, with only one case of ovarian cancer reported in a study of 619 patients with simple ovarian cysts 5
Management of Small Ovarian Cysts
- Conservative management is recommended for simple ovarian cysts less than 5cm in diameter with normal CA-125 levels 2, 3, 6
- Regular follow-up with sonography is necessary to monitor the cysts for changes in size or morphology 2, 3, 6
- Surgery may be indicated for cysts that increase in size, develop solid components, or have abnormal Doppler flow 2, 3