Uterus and Adnexae Imaging

Definition

An adnexal mass is a lump in the tissue of the adnexa of the uterus, usually in the ovary or fallopian tube. Adnexal masses can be benign or malignant.

Incidence and Pathogenesis

• Adnexal masses are detected in 1%–4% of pregnant women.

• One percent to 3% of adnexal masses detected in pregnancy are malignant (although usually of low malignant potential).

Diagnostic Features

• Cystic:

  • Follicular cysts are <3 cm, with no internal echoes.

  • Corpora lutea are 3–6 cm, with a color Doppler circumferential “ring of fire.”

  • Theca lutein cysts are multiloculated.

  • Cystadenomas are predominantly cystic but may have internal excrescences.

• Solid:

  • A fibroma may appear similar to a uterine myoma.

• Solid with cystic components:

  • Hemorrhagic cysts have internal echoes with “sludge.”

  • Endometriomas have blood in the cystic component.

  • Teratomas have multiple echogenic and cystic components and may have shadowing due to calcifications.

Differential Diagnosis

• Paraovarian cyst

• Hydrosalpinx

• Leiomyoma

Associated Anomalies

• Bilaterality

• Metastasis if malignant

Prognosis

• Resolution occurs in 80%–90% of cases.

• Lesions more likely to resolve include simple cysts <6 cm in diameter and those diagnosed before 16 weeks of gestation.

• Persistent and large masses are more likely to result in torsion (up to 25%, typically in the first trimester), rupture (0%–9%), or obstruction of labor (2%–17%).

• Malignancy occurs in 1%–3% of lesions overall.

Imaging

Management