The value of transrectal biplane ultrasound in assessing vaginal morphology and elasticity for the diagnosis of vaginal laxity

To investigate the utility of transrectal biplane ultrasound in assessing vaginal morphology and elasticity for the diagnosis of vaginal laxity. This descriptive study included 62 women with clinically diagnosed vaginal laxity syndrome (VLS) and 60 controls recruited at a tertiary gynecology unit. All participants underwent transrectal biplane ultrasound. Vaginal length and thickness were measured in the sagittal plane, and shear wave elastography (SWE) was used to assess vaginal elasticity through shear wave velocity (SWV) measurements. Vaginal cavity width was measured in the transverse plane. Vaginal length and thickness did not significantly differ between groups. However, vaginal cavity width and the SWV of the lower posterior vaginal wall during pelvic floor contraction were significantly different between the VLS and control groups (P < 0.05). Binary logistic regression identified vaginal cavity width as an independent predictor of VLS. Receiver operating characteristic (ROC) curve analysis revealed an area under the curve (AUC) of 0.956 for vaginal cavity width with an optimal cutoff of 2.785 cm, yielding 93.75% sensitivity and 84.62% specificity. Transrectal biplane ultrasound enables quantitative assessment of vaginal morphology and biomechanical properties in women with VLS, providing objective imaging evidence for the condition. Among the parameters evaluated, vaginal cavity width shows the strongest correlation with VLS and appears to be a promising imaging metric, although validation in multicenter studies is required.