Are Hypoechoic Lesions on Ovaries Simple Cysts?
No, hypoechoic ovarian lesions are not simple cysts—by definition, simple cysts must be completely anechoic (echo-free), not hypoechoic. 1, 2
Defining Simple Cysts vs. Hypoechoic Lesions
Simple cysts are strictly anechoic with a smooth thin wall (<3 mm), no internal elements whatsoever, and demonstrate acoustic enhancement. 1, 2
Hypoechoic lesions contain internal echoes (low-level echoes that appear gray rather than black on ultrasound), which automatically disqualifies them from being classified as simple cysts. 1, 3
The presence of any internal echoes—even subtle ones—changes the classification and management pathway entirely. 2
What Hypoechoic Ovarian Lesions Typically Represent
Hemorrhagic Cysts (Most Common)
Hemorrhagic corpus luteum cysts are the most frequent cause of hypoechoic ovarian lesions in premenopausal women, appearing as thick-walled cysts with characteristic internal echoes showing a reticular (lace-like) pattern or retracting clot with concave/angular margins. 2, 3
These lesions demonstrate peripheral vascularity on color Doppler with absent internal blood flow, which is critical for confirming their benign nature. 2
The overwhelming majority (92%) of hemorrhagic cysts show increased sound through-transmission despite their internal echoes, and 83% appear as heterogeneous masses—almost half being predominantly anechoic with hypoechoic material. 3
Other Differential Diagnoses
Endometriomas can appear hypoechoic with homogeneous low-level internal echoes (ground-glass appearance). 2
Solid components with low color score may appear hypoechoic and represent O-RADS 4 lesions (intermediate malignancy risk 10-50%). 2
Infarcted ovarian tissue from torsion can present as hypoechoic solid masses, sometimes with small cysts and pelvic fluid. 4
Critical Management Implications
Risk Stratification Depends on Specific Features
Classic hemorrhagic cysts ≤5 cm with reticular pattern or retracting clot are O-RADS 2 (<1% malignancy risk) and require no follow-up in premenopausal women. 2
Hypoechoic lesions >5 cm or those lacking classic hemorrhagic features warrant follow-up ultrasound at 8-12 weeks to confirm functional nature. 2, 5
Any hypoechoic solid component with internal vascularity (color score 1-3) elevates the lesion to O-RADS 4, requiring gynecology referral. 2
Color Doppler Is Mandatory
Always use color Doppler interrogation to confirm absence of internal vascularity before assuming hypoechoic material represents benign hemorrhagic content rather than solid tissue. 2
Failure to perform color Doppler assessment is a critical pitfall that can lead to misclassification of solid malignant components as benign hemorrhagic debris. 2
Menopausal Status Modifies Management
In postmenopausal women, any hemorrhagic-appearing (hypoechoic) cyst is atypical and requires referral to an ultrasound specialist or MRI, as these patients have higher baseline malignancy risk. 2
In premenopausal women, hypoechoic lesions with classic hemorrhagic features ≤5 cm can be managed conservatively without follow-up. 2, 5
Key Pitfalls to Avoid
Do not call hypoechoic lesions "simple cysts"—this terminology error can lead to inappropriate management, as simple cysts require no follow-up while hypoechoic lesions may need surveillance or intervention depending on their characteristics. 1, 2
Never assume hypoechoic material is benign without color Doppler confirmation of absent internal vascularity. 2
Ensure complete evaluation with both transvaginal and transabdominal views, as incomplete assessment may miss wall irregularities or solid components in larger lesions. 2, 5