[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