Uterine "twisting sign": A new potential ultrasonographic soft marker for deep endometriosis

The objective of the current study was to evaluate the "twisting sign," defined as uterine fundus rotation observed on transvaginal sonography (TVS), as a potential soft marker for deep endometriosis (DE) and its association with specific DE localizations and indirect signs.

A prospective observational study was conducted at an endometriosis referral center. We enrolled 158 reproductive-aged women with pelvic pain requiring specialist evaluation. Exclusion criteria included prior endometriosis diagnosis or conditions affecting uterine positioning, such as large myomas, uterine malformations, or previous pelvic surgery. Standardized TVS assessments, following IDEA (International Deep Endometriosis Analysis) criteria, were performed by a single experienced operator. The twisting sign was defined as a uterine rotation angle between 15° and 90° in the fundal transverse section.

The twisting sign was detected in 24.1% of participants and was significantly associated with posterior compartment DE, particularly rectosigmoid nodules (44.8.7% vs. 14.0%, P < 0.001) and uterosacral ligament involvement (41.4% vs. 23.3%, P = 0.046). It was also linked to indirect DE markers, including ovarian fixation to the uterine wall (37.9% vs. 19.4%, P = 0.031) and absence of the posterior sliding sign (37.9% vs. 9.3%, P < 0.001). Multivariate analysis confirmed the twisting sign as an independent predictor of rectosigmoid junction nodules (odds ratio [OR], 9.84 [95% confidence interval [CI], 1.69-58.83], P = 0.012) and absence of the posterior sliding sign (OR, 6.63 [95% CI, 1.88-24.34], P = 0.004).

The twisting sign may represent a novel and potentially valuable ultrasonographic marker of DE, particularly in the posterior pelvic compartment. It likely reflects mechanical distortion of the uterine axis due to DE nodules and adhesions. Multicenter validation is warranted.