Strain elastography (SE) will be utilized as a non-invasive imaging technique to evaluate tissue elasticity and biomechanical properties in women with stress urinary incontinence (SUI) and in continent controls. The primary aim is to determine whether SE can detect differences in paraurethral tissue stiffness between these groups. Given the established role of tissue elasticity in the pathophysiology of SUI, SE will be investigated as a potential diagnostic tool in urogynecological evaluations.

This prospective cohort study will be conducted at a tertiary referral center. All participants will undergo introital two-dimensional (2D) ultrasound in the midsagittal plane at rest. SE will be performed in three predefined suburethral regions of interest (ROIs):

• internal urethral orifice (IUO) level
• midurethra (MU) level
• external urethral orifice (EUO) level

The adipose layer (AL) between the external urethral meatus and the pubic symphysis will serve as the reference tissue, representing the softest anatomical structure in the region.

Descriptive and comparative statistical analyses will be conducted to assess differences in paraurethral tissue stiffness between the study groups.

It is hypothesized that SE will be able to detect differences in paraurethral tissue elasticity, with SUI being associated with increased tissue compliance. The study also aims to determine whether SE can reliably distinguish between varying degrees of tissue stiffness in women with SUI and continent controls.

Pathophysiological focus:

The study will explore key mechanisms underlying SUI, including:

• Weakened bladder neck support
• Impaired urethral stabilization due to increased tissue elasticity and collagen degradation
• While conventional 2D ultrasound provides anatomical information, it does not directly evaluate tissue biomechanics. In contrast, SE enables real-time visualization of tissue elasticity, offering a promising adjunct to traditional urogynecological assessment methods.

Standardization and Protocol

The study will follow a standardized protocol to ensure reproducibility and high-quality data. Key methodological elements include:

• Minimal probe compression during introital ultrasound to avoid artifacts
• Bladder emptying prior to examination to eliminate confounding effects
• Carefully standardized ROI placement across all patients
• Controlled image acquisition conditions to reduce variability

Future Directions

• Future research based on this study will aim to:
• Optimize SE protocols and refine ROI placement strategies
• Establish clinical cutoff values for differentiating tissue stiffness in SUI vs. continent women
• Assess the long-term effects of pelvic floor muscle training (PFMT) and vaginal estrogen therapy on paraurethral biomechanics
• Facilitate the integration of SE into routine urogynecological practice to support early diagnosis and personalized treatment strategies for SUI

Inclusion Criteria:

• Clinical diagnosis of stress urinary incontinence (SUI) based on patient history, physical examination, and/or urodynamic assessment.

Exclusion Criteria:

• Pelvic malignancy or history of pelvic radiation therapy
• Urge urinary incontinence (UUI) or detrusor overactivity
• Pelvic organ prolapse (POP) stage ≥ II (based on POP-Q classification)
• Pregnancy or recent postpartum status (less than 6 months postpartum)
• Neurological disorders affecting bladder function
• Recurrent urinary tract infections (UTIs) or active lower urinary tract infection
• Inability to undergo study procedures
• Cognitive impairment or psychiatric conditions affecting informed consent or compliance

This study will include adult women in Hungary diagnosed with stress urinary incontinence (SUI), along with a control group of continent women. Participants will be recruited from urogynecology outpatient clinics, tertiary referral centers, and gynecology departments.

Quantitative strain elastography measurements of periurethral tissue elasticity.