A 35-year-old nulliparous woman undergoes routine pelvic ultrasound and is found to have a 3 cm unilateral ovarian mass with a smooth contour and no internal vascularity on Doppler. The mass appears cystic with a thin wall. Serum tumor markers (AFP, β-hCG, inhibin) are normal. Which investigation is most appropriate to further characterize this lesion and guide management?

Explanation

## Management of Indeterminate Ovarian Mass in Young Woman **Key Point:** In reproductive-age women with indeterminate ovarian masses and normal tumor markers, conservative follow-up with repeat imaging is the standard approach before considering surgical intervention. ### Clinical Context and Risk Assessment This patient has several features favoring a benign lesion: - **Age 35** — low pretest probability of malignancy in reproductive age - **Unilateral, smooth, thin-walled cyst** — morphologic features of benign cyst - **No internal vascularity** — absence of neovascularization suggests benignity - **Normal tumor markers** — AFP, β-hCG, and inhibin rule out germ cell and sex cord–stromal tumors - **Nulliparity** — increased risk of ovarian cancer, but current imaging is reassuring ### Rationale for Repeat Ultrasound 1. **Functional cysts resolve spontaneously** — simple cysts <3 cm often regress within 6–8 weeks 2. **Avoids unnecessary surgery** — reduces morbidity and preserves ovarian function in reproductive-age women 3. **Cost-effective and safe** — ultrasound carries no radiation or contrast risk 4. **Standard guideline recommendation** — endorsed by ACOG and ASRM for indeterminate masses in young women ### Ultrasound Criteria for Benignity (IOTA Simple Rules) | Feature | Benign Indicator | |---|---| | **Size** | <3 cm | | **Morphology** | Unilocular cyst, no solid components | | **Vascularity** | No internal blood flow on Doppler | | **Wall characteristics** | Thin wall, no papillations | | **Septations** | None or thin septa (<3 mm) | **Clinical Pearl:** In reproductive-age women, the threshold for surgery should be high. A simple cyst with normal markers and benign ultrasound features can be safely followed. Surgery is reserved for masses that persist, grow, or develop suspicious features on follow-up imaging. **High-Yield:** The combination of young age, normal tumor markers, and benign ultrasound morphology makes malignancy unlikely. Repeat ultrasound in 6–8 weeks is the most appropriate next step to confirm resolution or stability before considering surgery. **Mnemonic: IOTA Simple Rules** — **I**nternational **O**varian **T**umor **A**nalysis criteria for distinguishing benign from malignant ovarian masses using ultrasound alone. [cite:Park 26e Ch 24]