What is the best course of action for a patient with a complex ovarian cyst?

Management of Complex Ovarian Cysts

For a complex ovarian cyst, perform transvaginal ultrasound with Doppler to assess for solid components or papillary projections, then use O-RADS risk stratification to guide management—complex cysts with solid components (O-RADS 4-5) require core needle biopsy or gynecologic oncology referral, while septated cysts without solid elements can be managed conservatively with surveillance. 1

Initial Diagnostic Evaluation

• Obtain transvaginal ultrasound combined with transabdominal imaging as the primary diagnostic modality 1
• Include color or power Doppler evaluation to assess vascularity of any solid components 1
• Document the following key features: maximum cyst diameter, presence and count of papillary projections, presence of ascites, and thickness of septations 1
• The critical distinction is whether the cyst has true solid components versus only septations—this fundamentally changes management 1

Risk Stratification Using O-RADS Classification

The O-RADS system provides a structured approach to determine malignancy risk:

• O-RADS 2 (almost certainly benign, <1% malignancy risk): Multilocular cyst <10 cm with smooth inner walls and septations only, no solid areas or papillary projections, color score 1-3 1
• O-RADS 3 (low risk, 1-10% malignancy risk): Multilocular cyst ≥10 cm with smooth inner walls, or any size with color score 4 1
• O-RADS 4 (intermediate risk): Cysts with some solid components or concerning features 1
• O-RADS 5 (high risk): Cysts with definite solid components, thick irregular septations, or papillary projections 1

The presence of papillary formations on the inside of the cyst wall and masses with solid components are the most statistically significant predictors of malignancy. 2

Management Algorithm Based on Risk Category and Menopausal Status

For O-RADS 2 Lesions (Septated Without Solid Components)

Premenopausal women:

• Cysts <5 cm: No additional management required 1
• Cysts 5-10 cm: Follow-up ultrasound in 8-12 weeks during the proliferative phase to confirm functional nature or reassess for wall abnormalities 1
• If the cyst persists or enlarges at follow-up, refer to a gynecologist 1, 3

Postmenopausal women:

• Cysts ≤3 cm: No further management required 1
• Cysts >3 cm but <10 cm: Follow-up ultrasound at 1 year showing stability or decrease in size, with consideration of annual surveillance up to 5 years if stable 4, 1
• If the cyst enlarges, refer to a gynecologist 4

For O-RADS 3 Lesions

• Refer to a general gynecologist for management 1
• Consider ultrasound specialist evaluation or contrast-enhanced MRI for further characterization of indeterminate features 1
• Complex cysts ≥10 cm should be managed by a gynecologist due to 1-10% malignancy risk 1

For O-RADS 4-5 Lesions (True Complex Cysts with Solid Components)

This is where the term "complex cyst" becomes clinically critical—these require tissue diagnosis:

• O-RADS 4: Require gynecologic oncology consultation prior to surgical removal or direct referral for management 1
• O-RADS 5: Direct referral to gynecologic oncologist is mandatory 1
• Perform core needle biopsy for complex cystic and solid masses, as these have a relatively high risk of malignancy (14-23% in published studies) 4
• Initial surgery by a gynecologic oncologist improves outcomes through complete staging and optimal cytoreduction 1

Role of Advanced Imaging

• Contrast-enhanced MRI performs superiorly to both ultrasound and noncontrast MRI for further characterization of indeterminate adnexal masses 1
• Noncontrast MRI may be used when IV contrast is contraindicated 1
• CT is usually not useful for further characterization, and PET/CT cannot reliably differentiate between benign and malignant adnexal lesions 1

Common Pitfalls to Avoid

• Failing to distinguish between septated cysts (low risk) and cysts with solid components (higher risk): The former can be managed conservatively, while the latter require biopsy 1
• Inadequate follow-up for complex cysts: Establish clear follow-up intervals based on cyst size and patient menopausal status 1
• Overtreatment of septated cysts without solid components: These rarely represent malignancy, particularly in premenopausal women 1, 5
• Underestimating risk in postmenopausal women: While simple cysts have low malignancy risk (1.5%), complex features warrant more aggressive evaluation 5, 6

Special Considerations

• In postmenopausal women, the risk of malignancy increases with age—symptomatic postmenopausal women with cysts ≥5 cm or raised CA125 levels should be referred to secondary care 7
• Functional cysts, particularly when <5 cm diameter, usually resolve spontaneously without intervention in premenopausal women 7
• The majority of unilocular ovarian cysts with diameter <50 mm in postmenopausal women are benign and remain unchanged, and can be managed expectantly when serum CA125 is normal 6