What is the approach for evaluating an adnexal mass?

Evaluation of Adnexal Mass

Transvaginal ultrasound combined with transabdominal ultrasound is the most appropriate initial imaging modality for evaluating any adnexal mass, with sensitivity exceeding 90% and should include color Doppler assessment of vascularity. 1

Initial Imaging Strategy

The combined transvaginal and transabdominal ultrasound approach is essential because the transvaginal component provides detailed evaluation of smaller masses while the transabdominal component captures larger lesions (>10 cm) that may be suboptimally visualized transvaginally. 1

Key Technical Components

• Color or power Doppler must be included as an integral part of the complete ultrasound examination to identify internal vascularity within solid components, which helps differentiate malignancy from benign solid elements like clot or debris. 1

• The transvaginal approach alone may be performed when transabdominal imaging cannot be tolerated, though a full bladder provides better acoustic windows for transabdominal evaluation. 1

Risk Stratification Systems

Multiple validated classification systems exist to standardize interpretation and improve risk-stratified management. 1

O-RADS (Ovarian-Adnexal Reporting and Data System)

• O-RADS demonstrates superior sensitivity for malignancy (96.8%) compared to IOTA simple rules (92.1%) with equivalent specificity (92.8% versus 93.2%). 1

• Uses color score ranging 1-4 (no flow to very strong flow) combined with morphologic features. 1

IOTA Simple Rules

• Employs a binary system (no flow versus very strong flow) for Doppler evaluation. 1

• Combines classically benign imaging features with assessment of lesion size, locularity, solid components, and vascularity. 1

SRU Consensus Statement

• Has been shown to decrease unnecessary follow-up of benign lesions while maintaining high sensitivity and specificity for detecting ovarian malignancy. 1

Features Suggesting Benign vs. Malignant Disease

Benign Characteristics

• Simple cysts establish a benign process in 100% of both premenopausal and postmenopausal women. 1

• Single thin septation <3 mm is considered benign. 1

• Classically benign lesions include follicles, functional cysts, hemorrhagic cysts, dermoids, and endometriomas. 1

Malignant Features

• Irregular thick septations, papillary projections, or mural nodules indicate variable to high risk of malignancy. 1

• Solid components with internal vascularity on Doppler. 1

• Presence of ascites. 2, 3

• Bilaterality. 2, 3

Second-Line Imaging: When and What

MRI Pelvis With and Without IV Contrast

• MRI with IV contrast is the best alternative imaging modality when ultrasound is inconclusive or limited by large mass size (>10 cm), poor acoustic window from body habitus or adjacent viscera, or unclear organ of origin. 1, 4

• Contrast-enhanced MRI performs superiorly to both ultrasound and noncontrast MRI due to its ability to confirm internal enhancing soft tissue components. 1

• Noncontrast MRI demonstrates sensitivity of 85%, specificity of 96%, and accuracy of 94.2% for detecting cancer, and may be used when IV contrast is contraindicated. 1

• MRI can accurately diagnose classically benign lesions (simple cysts, endometriomas, dermoids, extraovarian benign lesions) and can be confidently categorized as almost certainly benign. 1

CT Has Limited Role

• CT is usually not useful for initial workup and characterization of adnexal masses due to suboptimal soft tissue delineation in the adnexal region. 1

• CT's primary role is for staging known malignancies and follow-up posttreatment, not initial characterization. 1

• Some diagnostic features visible on CT include calcifications (teeth in teratoma), macroscopic fat, or uniform simple fluid attenuation. 1

FDG-PET/CT

• FDG-PET/CT has no role in initial evaluation or follow-up of benign adnexal masses in premenopausal patients. 1

• May play a role only in women with known history of malignancy to identify other sites of disease. 1

Clinical Symptoms Warranting Evaluation

• Pelvic or abdominal pain, increased abdominal size, bloating, urinary urgency/frequency, early satiety, difficulty eating, or weight loss occurring daily for more than two weeks warrant evaluation for ovarian pathology. 2, 3

• These vague symptoms are present for months in up to 93% of patients with ovarian cancer. 2

Referral Criteria

• All prepubescent girls and postmenopausal women with an adnexal mass should be referred to a gynecologist or gynecologic oncologist. 2

• Refer all women regardless of menopausal status if they have: evidence of metastatic disease, ascites, complex mass with malignant features, adnexal mass >10 cm (some sources suggest >6 cm), or any mass persisting longer than 12 weeks. 2, 3

Common Pitfalls to Avoid

• Do not rely solely on transabdominal ultrasound—the transvaginal component is essential for detailed evaluation. 4

• Do not omit color Doppler assessment—it is crucial for identifying vascular flow within solid areas to differentiate malignancy from benign components like clot. 1, 4

• Do not assume negative pelvic examination excludes pathology—pelvic examination has low sensitivity for detecting adnexal masses, and symptomatic women warrant further workup despite normal examination. 3

• Do not order CT for initial characterization—ultrasound and MRI have well-established superior roles for soft tissue evaluation. 1