Endometrial assessment in abnormal uterine bleeding: transvaginal ultrasound alone may not be good enough

To evaluate the proportion of optimal assessments of endometrial thickness (ET) achieved by transvaginal ultrasound (TVS) compared with a multimodal (MM) sonographic approach in women with abnormal uterine bleeding (AUB).

This prospective observational study was a subset of the EPI-SURE study conducted between June and November 2022 in a tertiary gynecology diagnostic referral center in the UK. All women aged ≥ 45 years with AUB who underwent TVS assessment of the endometrium were included. If the endometrium could not be visualized optimally on TVS, women were offered another method of endometrial assessment (MM approach), namely transabdominal ultrasound, transrectal ultrasound and/or saline contrast sonohysterography. We assessed the diagnostic performance of TVS compared with the MM approach in terms of the quality of endometrial visualization and measurement of ET, and used uni- and multivariable logistic regression analyses to evaluate associations between patient characteristics and imaging outcome.

We included 387 women who underwent TVS for endometrial assessment. In 245/387 (63.3%) cases, ET measurement was deemed optimal on TVS. The most common standalone reasons for suboptimal TVS were adenomyosis (37/142, 26.1%) and unfavorable uterine position (37/142, 26.1%), followed by uterine fibroids (21/142, 14.8%) and other pathologies or presence of intrauterine system (6/142, 4.2%). In 41/142 (28.9%) women, the reason for suboptimal TVS was multifactorial. The median angle of insonation on TVS in women with an unfavorable uterine position was 33° (interquartile range (IQR), 15-52°), which increased to 86° (IQR, 78-90°) on MM imaging (P < 0.0001). In cases with suboptimal TVS due to inadequate imaging of the uterine cavity and/or a suboptimal angle of insonation, ET measurement was significantly higher on TVS compared with the MM approach (median difference, -1.3 (95% CI, -1.7 to -0.9) mm; P < 0.0001). On multivariable analysis, factors associated significantly with suboptimal TVS included fibroids distorting the uterine cavity and younger age; women with fibroids had 10 times the odds of a suboptimal TVS assessment of the endometrium compared to those without. Cavity-distorting fibroids and higher body mass index were associated significantly with suboptimal MM imaging on multivariable analysis, with fibroids increasing the odds of this outcome by 4.2 times. A prespecified ET cut-off of ≥ 4.5 mm yielded a specificity of 85.8% (95% CI, 78.0-91.7%) with the MM approach for the diagnosis of endometrial cancer. Using the MM sonographic approach avoided the need for further procedures to assess the endometrium in 118/387 (30.5%) cases.

The MM sonographic approach is a better way to assess the endometrium compared with TVS alone in women presenting with AUB. The MM approach improved endometrial assessment by optimizing the angle of insonation and visualization of the uterine cavity, which resulted in significantly lower ET measurements and a higher specificity for endometrial cancer, thereby potentially reducing the number of invasive interventions, such as hysteroscopy and endometrial biopsy. © 2025 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.