What is an adnexal mass?

What is an Adnexal Mass?

An adnexal mass is any abnormal growth or structure located in the adnexa—the anatomical region encompassing the ovaries, fallopian tubes, and surrounding connective tissues adjacent to the uterus. 1, 2

Anatomical Definition

• The term "adnexal" refers specifically to masses arising from the ovary, fallopian tube, or surrounding pelvic tissues 1, 2, 3
• These masses represent a broad spectrum of conditions that can originate from gynecologic or non-gynecologic sources 4, 5

Clinical Spectrum

Benign vs. Malignant Nature

• The vast majority of adnexal masses are benign, though the primary goal of evaluation is always to exclude malignancy 1, 2, 4
• In pregnancy specifically, approximately 2% of adnexal masses are malignant, with most being early-stage disease 6
• In premenopausal women, simple cysts have less than 0.4% risk of malignancy 7
• In postmenopausal women, simple cysts establish a benign process in 100% of cases 8

Common Types by Population

In Premenopausal Women:

• Most simple cysts are functional (follicular or corpus luteum cysts) that resolve spontaneously 7
• Approximately 70% of functional cysts resolve within 8-12 weeks 7
• The most common benign cystic teratoma (dermoid cyst) has characteristic ultrasound features 6

In Pregnancy:

• Three-quarters of incidentally identified masses are simple cysts <5 cm 6
• Among complex masses requiring surgery, the distribution is: dermoid cysts (32%), serous/mucinous cystadenomas (19%), endometriomas (15%), and functional cysts (12%) 6
• Pregnancy-specific masses include hyperreactio luteinalis and luteomas 6

In Postmenopausal Women:

• Simple cysts occur in 17-24% of postmenopausal women and are typically benign 8
• Pedunculated leiomyomas (fibroids) are the most common solid adnexal masses, present in 20-30% of this population 6, 8

Clinical Presentation

Detection Methods

• Most adnexal masses are detected incidentally on physical examination or pelvic imaging 1, 2
• Pelvic examination has low sensitivity for detecting adnexal masses; negative findings should not deter further workup in symptomatic women 5

Symptom Patterns

• Many patients are asymptomatic 9
• When symptomatic, the most common complaint is pain (acute, intermittent, or subacute) 6, 9, 1, 2
• Red flag symptoms suggesting possible malignancy include: pelvic/abdominal pain, increased abdominal size, bloating, urinary urgency/frequency, early satiety, difficulty eating, and weight loss occurring daily for more than 2 weeks 4, 5, 3

Diagnostic Approach

Initial Imaging

• Transvaginal ultrasound is the essential first-line imaging modality for characterizing adnexal masses 6, 8, 7, 4, 5, 3
• Ultrasound should include color or power Doppler to assess vascularity and differentiate solid from cystic components 6, 8, 7

Ultrasound Characteristics

Benign Features:

• Simple cysts: anechoic, unilocular, smooth thin walls, no solid components 6, 7
• Single thin septation <3 mm is considered benign 6
• Endometriomas: low-level internal echoes, mural echogenic foci 6
• Teratomas: echogenic attenuating component or small horizontal interfaces 6, 9

Malignant Features:

• Thick or irregular septations (>2-3 mm), mural nodules, solid or papillary components, diameter >5 cm 6, 4
• Doppler flow to solid components, bilaterality, presence of ascites 4, 3

Key Clinical Pitfalls to Avoid

• Do not assume size alone determines malignancy risk—morphologic features on ultrasound are far more important than size in premenopausal women 7
• Do not mistake pedunculated fibroids for ovarian masses—always identify normal ovaries and blood supply from uterine vessels 6, 8, 9
• Do not rely solely on CA-125—it performs worse than ultrasound in distinguishing benign from malignant lesions and may be low with borderline and low-grade malignant tumors 8
• Do not assume all cystic masses are benign—continue evaluation until definitive diagnosis is obtained 9