Urodynamic studies

Urodynamic studies are tests which assess the function of the urinary tract. There are many different types, including uroflowmetry, pressure flow study, and leak point pressure. They're used to evaluate symptoms of lower urinary tract symptoms and urinary incontinence.

Uroflowmetry

• Only non-invasive urodynamic study
• Measures the volume of urine voided over time
• Should be done with ~150 mL in the bladder to prevent false positives
• Normal
  • Continuous, peaked, bell-shaped curve
  • Normal peak urine flow – > 30 mL/s
  • Duration < 30 seconds
• Abnormal
  • Flat/plateau curve (urine flow is constant but very low) -> urethral stricture
  • Saw-tooth curve -> detrusor sphincter dyssynergia
  • Flattened bell-shaped curve -> BPH

Pressure flow study

• Invasive urodynamic study
• Measures the detrusor pressure while voiding
• Gives information on bladder stability, contractility, and sensibility

Valsalva leak point pressure

• Measures the intraabdominal pressure at which urine loss occurs