From the Guidelines
Ovarian cysts smaller than 10 centimeters in diameter are generally considered benign, especially if they are simple cysts with thin walls, no solid components, and no internal septations, as evidenced by the American College of Radiology's O-RADS US risk stratification and management system 1.
Key Characteristics of Benign Ovarian Cysts
- Size: Simple cysts up to 10 cm in diameter are likely to be benign, even in postmenopausal patients 1
- Appearance on ultrasound: Simple cysts with thin walls, no solid components, and no internal septations are more likely to be benign
- Presence of solid components, septations, blood flow, and menopausal status are important factors in determining if a cyst might be concerning ### Management of Ovarian Cysts
- Simple cysts less than or equal to 5 cm in diameter in premenopausal patients do not require follow-up 2
- Simple cysts greater than 5 cm but less than 10 cm in premenopausal patients may require follow-up in 8-12 weeks to confirm their functional nature or to reassess for cyst wall abnormalities 1
- Postmenopausal patients with simple cysts greater than 3 cm but less than 10 cm should have at least 1-year follow-up showing stability or decrease in size, with consideration of annual follow-up for up to 5 years if stable 1 ### Importance of Evaluation by a Healthcare Provider
- Any ovarian cyst should be evaluated by a healthcare provider to determine appropriate management based on its specific characteristics
- The healthcare provider should consider the cyst's appearance on ultrasound, size, and other factors to determine the best course of action
- Regular follow-up and monitoring may be necessary to ensure the cyst does not cause symptoms or become malignant 2
From the Research
Ovarian Cyst Size and Benignity
- The size of ovarian cysts considered benign can vary, but several studies provide insight into this matter 3, 4, 5, 6, 7.
- According to a study published in 2014, functional cysts, particularly when they are < 5 cm diameter, usually resolve spontaneously without the need for intervention 3.
- Another study from 2001 suggests that conservative management of simple cysts (anechoic, diameter < 5 cm with normal Doppler and CA 125 serum level) is more reasonable and safer than surgical treatment 4.
- A 2020 study found that 1-3 cm cysts represented the most common size range (> 40%) in postmenopausal women, with the majority being stable over follow-up with a benign outcome, supporting a 3 cm size threshold for simple cyst follow-up in postmenopausal women 5.
- A 1998 study reported that simple ovarian cysts less than 5 cm in greatest diameter can be classified as benign lesions and can be followed conservatively, with a low likelihood of malignancy 6.
- The American College of Obstetricians and Gynecologists (ACOG) states that simple cysts found on ultrasound may be safely followed without intervention, even in postmenopausal women, as they are not likely cancer precursors or markers of increased risk 7.
Size Thresholds for Benign Ovarian Cysts
- A size threshold of < 5 cm is often considered for benign ovarian cysts in premenopausal women 3, 4.
- For postmenopausal women, a size threshold of < 3 cm may be appropriate for simple cyst follow-up, with the majority of cysts in this size range being stable and benign 5.
- Cysts larger than 5 cm in postmenopausal women or those with raised CA125 levels may require referral to secondary care for further evaluation 3.