[US] Case 181

臨床問題：20歲女性，右下腹痛伴隨嘔吐情形，持續五天

超音波：

解析：Right ovary shows grossly edematous, with a nodular appearance. No vascularity inside the right ovary. Ovarian torsion is first considered; ddx: ovarian neoplasm, PID: tubo-ovarian abscess, hemorrhagic cyst.

**Ovarian torsion

多出現在適合懷孕年齡，增加機率的因子有adnexa mass, 和懷孕。超音波影像特徵多元，如：enlarged (>4cm) ovary, ovarian edema, variable echogenicity, peripherally displaced follicle (”string of pearls” sign), absence of flow (complete torsion), increased diastolic flow in edematous ovary (incomplete torsion)

**Ovarian neoplasm

惡性或良性皆有可能發生，幾乎不會有急性腹痛的情形（除非伴隨torsion)，一般來說病人較年長，會想到腫瘤的US特徵：thicken septation (2-3mm), solid component, vegetation(小突起), increased vascular flow

**PID / TOA

注意臨床表現，通常伴隨有fever, cervical motion tenderness, vaginal discharge。US通常也可以發現hydrosalpinx. complex multiloculated mass (TOA)

**hemorrhagic cyst

無血流。急性期有lacelike echoes, 之後可能會出現fluid-fluid level

答案：ovarian torsion

Reference: Radiopaedia, https://radiopaedia.org/cases/ovarian-torsion-10