Management of Persistent Simple Ovarian Cysts
For simple ovarian cysts that persist without resolution, continued ultrasound surveillance is appropriate without routine laboratory testing, as these cysts carry a near-zero malignancy risk regardless of size or menopausal status. 1
Evidence Supporting Conservative Management
The most recent and robust evidence demonstrates that simple ovarian cysts are essentially benign:
Large-scale studies involving over 72,000 women show an absolute 3-year ovarian cancer risk of 0 to 0.5 cases per 10,000 women with simple cysts—no different from women with normal ovaries. 1
Simple cysts are not cancer precursors and approximately 32% resolve spontaneously within one year, while 13-14% of postmenopausal women develop new simple cysts during follow-up. 1
The current understanding is that invasive serous cystadenocarcinoma originates from solid precursors in the fallopian tube (serous tubal intraepithelial carcinoma), not from simple ovarian cysts, further supporting their benign nature. 1
Recommended Follow-Up Strategy
Ultrasound Surveillance
Transvaginal ultrasound with color or power Doppler is the primary follow-up modality for persistent simple cysts. 1
For postmenopausal women: Follow-up is recommended only for simple cysts >3 cm (or >5 cm if exceptionally well-visualized), representing an updated threshold from previous 1-cm recommendations. 1
Color or power Doppler should be included to differentiate true solid components from debris and assess for concerning vascular patterns. 1
The rationale for continued surveillance is based on potential risk of mischaracterization of larger cysts, not actual malignant potential. 1
Laboratory Testing: CA-125
CA-125 testing is NOT routinely indicated for simple ovarian cysts, as it provides limited diagnostic value and may lead to unnecessary interventions. 1, 2
Here's why CA-125 should generally be avoided:
CA-125 has only 50% sensitivity for stage I ovarian cancer, meaning it misses half of early malignancies even when present. 1, 3
CA-125 performed worse than ultrasound alone in distinguishing benign from malignant lesions and only improved specificity for lesions already suspected to be malignant on imaging. 1
False-positive elevations occur commonly with benign conditions including endometriosis, pelvic inflammatory disease, and benign cysts themselves. 1, 4
For truly simple cysts (unilocular, anechoic, thin-walled), CA-125 adds no meaningful information since the malignancy risk is already established as near-zero by imaging characteristics. 1, 2
When to Consider CA-125 Testing
CA-125 may have limited utility in specific scenarios:
When the cyst develops concerning features on ultrasound (solid components, papillary projections, thick septations >3mm, abnormal vascularity). 1, 5
In postmenopausal women with cysts that are indeterminate or complex on imaging, where CA-125 >35 U/mL has 98.5% specificity. 1, 2, 3
When combined with resistive index <0.5 on Doppler, raising the CA-125 cutoff to 65 U/mL can achieve 100% specificity and positive predictive value. 1
Indications for Further Intervention
Surgery or advanced imaging (MRI) should be considered when:
- Progressive increase in cyst size on serial ultrasounds 5, 6
- Development of solid components, papillary projections, or thick septations 5, 6
- Abnormal Doppler flow patterns suggesting neovascularity 5
- Cyst becomes symptomatic 6
- Patient preference for removal or non-compliance with surveillance 5
Advanced Imaging Considerations
MRI with IV contrast is the next step for cysts that become indeterminate on ultrasound, not CT scanning. 1
MRI is superior to CT for characterizing adnexal masses and determining organ of origin. 1
CT has little role in further characterization of indeterminate lesions given MRI's established superiority. 1
Critical Pitfalls to Avoid
Do not obtain CA-125 reflexively for simple cysts, as this leads to unnecessary anxiety and interventions when false-positive results occur. 1, 2
Ensure ultrasound quality is adequate—the diagnosis of "simple cyst" requires expertise in ovarian imaging, as mischaracterization is the primary risk. 1, 5
Do not use PET/CT for characterization, as it cannot reliably differentiate benign from malignant adnexal lesions and has low uptake in certain malignant subtypes. 1
Remember that borderline and low-grade malignancies may have normal CA-125 levels, so reassuring CA-125 does not eliminate all risk if imaging features are concerning. 1, 2