Transperineal Ultrasonography in Stress Urinary Incontinence

Application of the ultrasound transducer to the patient's perineum can visualise three female pelvic compartments, and the images can be frozen to assess the positions of anatomical structures in relation to the pelvic bones and the pre-set planes as well as measure their mutual distances and predefined angles.

The aim of the study was to assess the utility of ultrasound in the detection of UI, particularly for establishing the most useful anatomical and functional parameters and to propose cut-off points for ultrasonographic parameters. The presence of stress urinary incontinence (SUI) requiring surgical management was the inclusion criterion. All patients underwent transperineal ultrasound (TPU) with a Voluson E6 (GE Medical systems, Milwaukee, WI, USA). The probe was oriented to coaxially visualise the pubic symphysis on one side and the anus and rectum on the other side of the 2D image. When all three compartments could not be visualised in one image, one image showing the anterior and medial compartments and another image showing the medial and posterior compartments were obtained instead. Next, 3D/4D ultrasound was performed to obtain an image in the coronal plane at the level of the arms of the levator ani muscle, showing the pubic symphysis and the anus. All measurements were performed in three states: during pelvic muscle relaxation, during Valsalva manoeuvre, and during perineal squeezing. The following quantitative parameters were assessed and compared across two arms of the study (with and without SUI):

• Bladder-symphysis distance (BSD) - measured as the distance between the urine bladder neck and the symphysis,
• Alpha angle - the angle between the axis of the proximal urethra and the x-axis of the symphysis pubis (central line),
• Beta angle - the angle between the line parallel to the proximal urethra and the line parallel to the distal axis of urethra,
• Gamma angle - the angle between the lower margin of the symphysis pubis and the urinary bladder neck),
• Retrovesical angle (RVA) - the angle between the axis of the proximal urethra and the tangent line to the lowest part of the posterior wall of the urinary bladder,
• Mean urethral diameter - the sum of the urethral diameters at three points (proximal, central, and distal parts) divided by 3.

Inclusion criteria

• Stress Urinary Incontinence

Exclusion criteria

• Failure to obtain endpoint measurements due to lack of cooperation during the ultrasound examination
• Prior surgery for either UI or POP
• Pelvic tumours
• Lack of consent to participate in the study