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Related Experiment Videos

Relationship between bladder neck diameter and hydraulic energy at maximum flow

M Tojo1, K Yasuda, T Yamanishi

  • 1Department of Urology, School of Medicine, Chiba University, Japan.

The Journal of Urology
|July 1, 1994
PubMed
Summary

This study identified the "flow rate controlling zone" in males. In men with wider bladder necks, this zone is the external urethral sphincter; in those with narrower necks, it

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Area of Science:

  • Urology
  • Fluid dynamics
  • Physiology

Background:

  • Bladder outlet obstruction is a common urological issue.
  • Identifying the precise location of flow limitation is crucial for effective treatment.
  • Previous studies have not definitively localized the primary resistance zone in the male urethra.

Purpose of the Study:

  • To investigate the location of the primary resistance zone influencing urinary flow rate.
  • To differentiate the flow controlling zone based on bladder neck diameter.
  • To apply fluid dynamics principles to understand urethral pressure and energy loss.

Main Methods:

  • Performed pressure-flow studies using a 5-micro-tip transducer catheter.
  • Measured intraurethral pressure at multiple sites during maximum flow.

Related Experiment Videos

  • Calculated hydraulic energy loss using the Bernoulli equation.
  • Compared energy loss at the external urethral sphincter and bladder neck.

    • Main Results:

    • Subjects were divided into groups based on bladder neck diameter (≥0.73 cm vs. ≤0.60 cm).
    • Relative hydraulic energy loss at the external urethral sphincter was significantly higher (p < 0.01) in the wider bladder neck group.
    • Relative hydraulic energy loss was greater at the bladder neck in the narrower bladder neck group.

    Conclusions:

    • The external urethral sphincter acts as the primary flow rate controlling zone in males with larger bladder neck diameters.
    • The bladder neck is the primary flow rate controlling zone in males with smaller bladder neck diameters.
    • This finding has implications for diagnosing and managing bladder outlet obstruction.