From the Guidelines
Urodynamic findings in stress urinary incontinence are crucial for confirming the diagnosis, determining the severity of the condition, and guiding appropriate treatment selection. The key diagnostic finding is urine leakage that coincides with increased abdominal pressure (such as during coughing or Valsalva maneuver) while bladder pressure remains unchanged, confirming genuine stress incontinence 1. Other characteristic findings include normal bladder filling sensation, normal bladder capacity (usually 300-500 ml), and absence of uninhibited detrusor contractions. Urethral pressure profilometry often reveals decreased maximum urethral closure pressure (MUCP), with values below 40 cmH2O suggesting intrinsic sphincter deficiency. The abdominal leak point pressure (ALPP) is another important measurement, with values below 60 cmH2O indicating severe intrinsic sphincter deficiency, while values between 60-90 cmH2O suggest moderate deficiency 1. Some of the key points to consider when interpreting urodynamic findings in stress urinary incontinence include:
- The importance of urodynamic testing in confirming the diagnosis and guiding treatment selection 1
- The role of urethral pressure profilometry and abdominal leak point pressure in assessing the severity of intrinsic sphincter deficiency 1
- The need to exclude other conditions that may mimic stress incontinence, such as detrusor overactivity or mixed incontinence 1
- The value of urodynamic testing in determining the best course of treatment, whether conservative measures like pelvic floor therapy or surgical interventions such as midurethral slings 1 It is essential to consider the most recent and highest quality studies when making a definitive recommendation, and the 2023 update to the AUA/SUFU guideline on surgical treatment of female stress urinary incontinence provides the most current and comprehensive guidance on this topic 1.
From the Research
Urodynamics Findings for Stress Incontinence
Urodynamics findings for stress incontinence include several key measures, such as:
- Maximum urethral closure pressure
- Valsalva leak point pressure
- Urethral axis
- Stress urethral axis These measures are used to diagnose intrinsic sphincteric deficiency and assess the severity of stress urinary incontinence 2.
Diagnostic Criteria
The diagnostic criteria for intrinsic sphincteric deficiency include:
- Maximum urethral closure pressure < or = 20 cm H2O
- Valsalva leak point pressure < or = 50 cm H2O
- Stress urethral axis < or = 20 degrees These criteria are used in combination with clinical severity criteria to diagnose intrinsic sphincteric deficiency 2.
Urodynamic Parameters
Urodynamic parameters, such as urethral functional length and urethral closure pressure, are altered in patients with stress urinary incontinence 3.
- Decrease in urethral functional length under the stress of bladder filling and change of position
- Decrease in urethral closure pressure
- Decreased ability to voluntarily increase urethral pressure
- Pressure equalization on Valsalva maneuver and coughing
Role of Urodynamics
The role of urodynamics in stress urinary incontinence is debated, with some studies suggesting that preoperative urodynamics do not improve outcome of incontinence surgery in women with uncomplicated stress urinary incontinence 4. However, urodynamic study can provide valuable information on:
- Detrusor overactivity
- Voiding inefficiency
- Asymptomatic detrusor overactivity
- Severity of stress urinary incontinence This information can influence the choice of treatment and predict outcome 5.
Predictive Measures
Urethral closure pressure at stress (s-UCP) is a predictive measure for the diagnosis and severity of urinary incontinence in women 6.
- s-UCP values less than or equal to 20 cm H2O had a sensitivity of 73.1% and a specificity of 93.0% for predicting stress urinary incontinence
- s-UCP is strongly inversely correlated with the severity of stress urinary incontinence.