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ovErviEw oF tHE EvalUation oF lowEr Urinary tract dysFUnction

in patients with a small contracted bladder and increased due to repeated stretching in patients with chronic outflow obstruction.

•Abdominal leak point pressure – is the intra-vesical pressure at which urine leakage occurs due to increased abdominal pressure in the absence of detrusor contraction. It measures the ability of the bladder neck and the urethral sphincter mechanism to resist increases in intraabdominal pressure.

•Detrusor leak point pressure – is the lowest detrusor pressure at which urine leakage occurs in the absence of either a detrusor contraction or increased abdominal pressure. It measures the capacity of the bladder neck and urethral sphincter mechanism to resist increased pressure.

Abnormal findings include:

•Detrusor overactivity – activity during storage or associated with episodes of urgency or incontinence

•Poor bladder compliance/capacity – usually noted with small shrunken fibrotic bladders

•Low abdominal leak point pressure – increases in intra-abdominal pressure will precipitate stress urinary incontinence

•Lowdetrusorleakpointpressure–Increases in bladder pressure will precipitate stress urinary incontinence

Measurements During the Voiding Phase:

•Premicturition pressure – pressure recorded prior to the initial isovulometric contraction in the bladder

•Opening pressure – pressure recorded at the onset of urine flow

•Opening time – time from initial rise in detrusor pressure to actual flow

•Maximum pressure – peak amplitude of voiding pressure

•Pressure at maximum flow – lowest pressure recorded at maximum flow rate

•Closing pressure – the pressure as measured at the end of flow

•Minimum voiding pressure – minimum pressure sufficient to produce flow

Abnormal findings include:

•Detrusor underactivity – A detrusor contraction insufficient to achieve complete bladder emptying

•Acontractile detrusor – No detrusor activity

•Bladder outflow obstruction – characterized by increased detrusor pressures and reduced flow rates

Video dynamics during voiding may be able to visualize the bladder outlet and urethra defining the level of obstruction. Also during video urodynamics the stop test maybe performed. The patient is asked to stop their void. During this the urine lying between the bladder neck sphincter and the distal prostatic sphincter is normally pushed back into the bladder, however in patients with bladder neck hypertrophy this urine is unable to return to the bladder and is captured via contrast screening.

Abnormal Function

Disordered lower urinary tract function can result from:

•Disruption of the normal peripheral or central nervous system (CNS) control mechanisms

•Disordered bladder muscle function, either primary (of unknown etiology) or secondary to an identifiable pathology such as prostaticmediated bladder outflow obstruction.

Patients who have disordered lower urinary tract function in routine clinical practice represent a heterogeneous collection for most of whom there is no identifiable neurological abnormality. Some of these patients will have a primary neural or muscular disorder (e.g. primary idiopathic detrusor overactivity) in contrast to post-obstructive secondary detrusor overactivity where the major etiological factor is likely to be peripheral disruption of local neuromuscular function.

It is essential to use standardized terminology when discussing lower urinary tract symptoms (LUTS) and the results of urodynamic investigations, to allow accurate exchange and comparison of information for clinical and research purposes. The official terminology is as