Detrusor Overactivity in Urology

Detrusor Overactivity (DO)

• DO is characterized by a rise in amplitude during pressure/flow cystometry, often with associated leakage and urgency.
• There are two types of DO: neurogenic detrusor overactivity (NDO) with a known neurological cause, and idiopathic detrusor overactivity (IDO) with an unknown cause.
• DO was previously known as detrusor instability, and NDO was previously known as detrusor hyperreflexia.
• During cystometry, the volume at which DO occurs and the rise in amplitude should be documented, as well as any associated leakage.
• It is also important to note if the DO was spontaneous or provoked.

Characteristics of DO

• Phasic contraction activity with increasingly frequent and higher amplitude contractions often occurs as the bladder continues to be filled.
• A large terminal contraction typically occurs, at which point the patient feels that they can no longer delay micturition and has reached maximum cystometric capacity.
• If voiding is delayed, the patient will frequently be incontinent.

Cough-Induced Incontinence

• Coughing can provoke urinary incontinence due to the abrupt change in intra-abdominal pressure.
• This is often confused with stress incontinence on the history alone, but during video urodynamics, DO is seen immediately following a cough with associated urinary leakage.
• Changing patient position, such as to the standing position, may similarly trigger DO.

Stress Urinary Incontinence (SUI)

• SUI is predominantly a female problem, affecting between 4% and 35% of the adult female population, with an apparent increase in prevalence with age.
• In men, SUI is most commonly seen in patients following a radical prostatectomy.
• The current International Continence Society definition of SUI is "the complaint of involuntary leakage on effort or exertion, or on sneezing or coughing".
• If involuntary leakage is observed during increased abdominal pressure, in the absence of a detrusor contraction during a urodynamic assessment, then the patient is described as having urodynamic stress incontinence.

Causes of Stress Incontinence

• SUI can affect females of any age and parity, but is particularly common in multiparous women who have had traumatic or prolonged vaginal deliveries.
• The causes of SUI include loss of pelvic floor support and/or damage to the sphincter mechanism, resulting in either:
  • Descent or hypermobility of the bladder neck and proximal urethra.
  • Intrinsic sphincter deficiency (ISD).

Treatment Options

• Initial therapy can be commenced empirically by the primary care physician.
• If this fails, the patient should be evaluated in secondary care for consideration of invasive management.
• Available treatment choices include:
  • Fluid intake advice.
  • Pelvic floor muscle training.
  • Devices (e.g. pads, adult nappies/diapers, cones, urethral plugs, electrical stimulation).
  • Bulking agents (to increase urethral resistance).
  • Sphincter cell injection therapies (currently at an investigative stage).