In a premenopausal woman with a small (<5 cm) hypoechoic ovarian lesion lacking internal Doppler flow, is it considered a simple cyst?

Hypoechoic Ovarian Mass Without Internal Vascular Flow

A hypoechoic ovarian lesion without internal Doppler flow is NOT automatically a simple cyst—it may represent a hemorrhagic cyst, endometrioma, or other complex lesion that requires different management than a true simple cyst. 1

Defining a True Simple Cyst

A simple ovarian cyst must meet strict ultrasound criteria to be classified as such and managed conservatively: 2, 3

• Completely anechoic fluid content with no internal echoes
• Thin, smooth wall without thickening or irregularity
• No septations, solid components, or nodularity
• No vascularity on color Doppler imaging

The term "hypoechoic" indicates the presence of internal echoes, which by definition excludes the lesion from being classified as a simple cyst. 2

What a Hypoechoic Lesion May Represent

Hemorrhagic Cyst (Most Common in Premenopausal Women)

• Contains blood products with low-level internal echoes creating a hypoechoic appearance
• May show retracting clot and peripheral vascularity (not internal flow)
• Typically resolves in 8-12 weeks on follow-up ultrasound 1, 3

Endometrioma

• Classically demonstrates "ground glass" low-level internal echoes (hypoechoic)
• Usually lacks internal vascularity
• Requires yearly surveillance due to small malignant transformation risk (<1%) 1, 2

Other Considerations

• Dermoid cysts can have variable echogenicity
• Early complex cystic lesions may appear hypoechoic

Management Algorithm for Small (<5 cm) Hypoechoic Lesions in Premenopausal Women

If Hemorrhagic Cyst Features Present

• Follow-up ultrasound in 8-12 weeks (during proliferative phase after menstruation) 1, 3
• Expect resolution or significant decrease in size
• If persistent or enlarging, refer to gynecology or consider MRI 1

If Endometrioma Features Present

• Optional initial follow-up at 8-12 weeks, then yearly surveillance if stable 1, 2
• Annual ultrasound monitoring is recommended long-term 1

If Features Are Indeterminate

• Transvaginal ultrasound with color/power Doppler to assess for any solid components or vascularity 1
• MRI with contrast serves as the problem-solving tool when ultrasound is indeterminate 1
• Contrast-enhanced MRI achieves 85% sensitivity and 96% specificity for detecting malignancy 2

Critical Pitfalls to Avoid

Do not assume absence of internal flow equals benignity—solid components without vascularity can still represent malignancy, though this is less common. 1

Do not label hypoechoic lesions as "simple cysts" in radiology reports, as this creates management confusion and may lead to inappropriate surveillance intervals. 2, 3

Do not skip follow-up imaging—even benign-appearing hemorrhagic cysts require documentation of resolution to exclude mischaracterization. 1, 3

Risk Context

• The malignancy risk for true simple cysts <10 cm in premenopausal women is 0.5-0.6%, with zero malignancies found in large cohorts of women <50 years 2
• Hemorrhagic cysts ≤5 cm in premenopausal women require no further management after confirmation of resolution 2
• The risk of acute complications (torsion, rupture) in conservatively managed benign-appearing lesions is 0.2-0.4% 2