Application value of biplane ultrasound combined with multimodal ultrasound elastography and ultra-micro angiography in stress urinary incontinence: a prospective clinical study.

BACKGROUND: Stress urinary incontinence (SUI) is the most prevalent phenotype of female urinary incontinence. Conventional pelvic-floor ultrasound depends on a patient-performed Valsalva maneuver and therefore often fails to detect incipient or occult SUI. Transvaginal biplane ultrasound (TV-BPUS) combined with shear-wave elastography and ultra-micro angiography (UMA) can quantify urethral sphincter thickness, stiffness, and microperfusion at rest, allowing for subclinical alterations to be visualized. The aims of this study were to validate the diagnostic performance of this multiparametric approach, construct a logistic prediction model, and provide an objective imaging tool for the early identification of female SUI.

METHODS: From August 1 to December 31, 2024, we prospectively recruited 50 women with clinically and sonographically confirmed SUI and 52 controls at The First Affiliated Hospital of Guangzhou Medical University. After bladder emptying, TV-BPUS integrated with shear-wave elastography and UMA was performed at rest to capture multiparametric data from both the internal urethral orifice and the mid-urethra. Continuous variables were first tested for normality; between-group differences were then evaluated with the independent-samples t test or Mann-Whitney U test, while categorical variables were compared via the χ2 test. To avoid overfitting, candidate predictors were screened via least absolute shrinkage and selection operator (LASSO; 10-fold cross-validation with the one-standard-error criterion) regression, and residual collinearity was examined via Spearman correlation. Finally, a parsimonious multivariable logistic model was constructed, and its discriminative performance was quantified via receiver operating characteristic curve analysis with 95% confidence intervals.

RESULTS: There were significantly lower maximum and mean Young moduli (maximum E value and mean E value) and maximum viscous and mean viscous values at the internal urethral orifice on elastography in patients with SUI cohort than in controls (all P values <0.05). In UMA, there were markedly reduced microvascular parameters, including vascular density (VD), flow-perfusion index (FPI), number of branch points per unit area (NBPPA), and resistance index (RI) in patients with SUI (all P values <0.05). Nine key indices were retained after LASSO screening. The final logistic model, which included age, body mass index (BMI), internal urethral orifice VD, FPI, NBPPA, RI, systolic-to-diastolic ratio (S/D), and maximum E value of both the internal urethral orifice and mid-urethra, achieved an area under the curve of 0.9327, with a sensitivity of 88% and a specificity of 84.6%.

CONCLUSIONS: TV-BPUS integrated with elastography and UMA demonstrated excellent accuracy in diagnosing female SUI. By quantifying urethral elasticity and microvascular alterations, the technique reliably identifies early and occult disease, offering a novel, reproducible imaging basis for clinical decision-making, therapy guidance, and prognostic evaluation.