pre and post void residual volumes and also highlighting bladder mucosal abnormalities.

Further Diagnostic Evaluation of Patients

Urodynamic Assessment:When Should Urodynamic Testing Be Performed?

Women with a history of pure stress urinary incontinence associated with urethrovesical hypermobility and no prior history do not necessarily require urodynamic evaluation prior to surgery for stress incontinence.10,11 However a diagnosis if made on the basis of history alone will not exclude detrusor overactivity in up to 25% of cases.Urodynamic assessment is therefore an important preoperative requisite in women with stress incontinence; particularly those who have other associated abnormalities or risk factors identified from their history and physical examination that may complicate the presentation and thereby influence treatment.12,13

These include:

•Women with significant overactive bladder symptoms or mixed stress-urgency incontinence14

•Those with recurrent incontinence following previous surgery

•Patients with associated neurological disease, and those whose presentation suggests predominantly intrinsic sphincter deficiency. Women who are dysfunctional voiders with high postvoid residual urine volumes are considered at higher risk of postoperative retention and should be urodynamically evaluated. Pure urgency incontinence not responding to behavioral and pharmacological management is also an indication for study

Male patients can only be clearly defined as being obstructed on the basis of a pressure/flow urodynamic assessment. Whilst the evidence base relating to this is based on observational studies there is a current consensus view that patients are more likely to have a better outcome following surgery for lower urinary tract symptoms if they are obstructed.

Certainly all symptomatic patients with neuropathic bladder dysfunction should undergo urodynamics, and preferably videourodynamics, in order to accurately characterize the detrusor

and sphincteric abnormalities, and to help identify patients who are at renal risk from their lower tract abnormality.More sophisticated electrophysiological studies are useful in the diagnosis of neuropathic bladder. The most commonly studied patients are those with multiple sclerosis, stroke, diabetes, Parkinson’s disease, and spinal cord injury.

Cystometry with or Without Video

The majority of urodynamic units do not have the benefit of fluoroscopically equipped facilities.In the assessment of the majority of patients presenting with urinary incontinence,frequency and/or urgency simple cystometry provides all of the necessary information. Synchronous cystography and cystometry recordings are most important in the assessment of complex cases, particularly where previous surgery has failed; since this investigation allows a combined anatomical and functional evaluation of lower urinary tract function. Nevertheless it must be remembered that simple cystourethrography can be carried out in all X-ray departments and can provide true, high quality, lateral views of the urethra during voiding.15,16

Cystometry

In equivocal or more complex cases, detailed urodynamic investigation is necessary. Cystometry is the method by which the pressure/volume relationship of the bladder is measured.The term cystometry is usually taken to mean the measurement of detrusor pressure during controlled bladder filling and subsequent voiding with measurement of the synchronous flow rate (filling and voiding cystometry). In simple cystometry the intravesical (total bladder) pressure is measured while the bladder is filled. It is not accurate as it assumes that the detrusor pressure approximates the intravesical pressure. However, as the bladder is an intra-abdominal organ, the detrusor pressure is subject to changes in the intra-abdominal pressure which may lead to inaccurate diagnoses. Subtracted cystometry involves the measurement of both the intra-vesical and the intra-abdominal pressure simultaneously. Electronic subtraction of the latter from the former enables the detrusor pressure to be determined. Cystometry helps characterize detrusor function by assessing bladder compliance, sensation, stability, and capacity.