Urodynamic Testing Guidelines

Introduction to Urodynamic Testing

The American Urological Association (AUA) guidelines recognize that proper medical history and physical examination are integral in determining the etiology of complex lower urinary tract symptoms, but urinary symptoms and physical findings often do not adequately predict the underlying pathophysiology 1
Urodynamic testing helps reproduce the patient's symptoms and determine their cause 1

It provides objective information about what is wrong with the lower urinary tract, helping understand underlying mechanisms for both filling and voiding phases, and increases accuracy of prognosis and enables effective patient counseling 2

A study found significantly better postoperative outcomes in patients who underwent urodynamic evaluation before treatment compared to those who had office evaluation only, and women who received treatment concordant with their urodynamic findings were more likely to report improvement in bladder symptoms (57% vs 45%; p=0.02) 2

Urodynamic testing carries a small risk of discomfort, embarrassment, and urinary tract infection 2

The AUA guidelines note there is insufficient evidence to recommend for or against the use of urodynamics over other methods of assessing bladder function in all cases, but urodynamic studies should be performed in patients with urinary retention when invasive or irreversible treatments are being considered 1, 3
Urodynamic studies are indicated when planning invasive treatment, especially in men with maximum flow rate (Qmax) >10 ml/second, and in patients with neurological conditions affecting bladder function, especially when storage parameters place upper tracts at risk 4, 5, 6
Pressure flow urodynamic studies are the only method to differentiate between detrusor underactivity (weak bladder muscle) and bladder outlet obstruction 1, 4

Uroflowmetry should be performed when voiding dysfunction is suspected, with at least 2 flow rates obtained (ideally with >150ml voided volume), and can assess flow rate pattern, voiding time, and maximum flow rate, helping to differentiate between bladder outlet obstruction and detrusor underactivity 1, 4
Maximum flow rate (Qmax) is the best single measure of voiding function 4
Pressure flow studies (PFS) are the gold standard for diagnosing obstruction, relating detrusor pressure at maximum flow to the maximum flow rate 4
Multichannel filling cystometry is preferred over single channel cystometrogram for evaluating storage phase abnormalities, assessing for altered compliance, detrusor overactivity, or other abnormalities 1
Post-void residual (PVR) measurement via ultrasound is a non-invasive method that eliminates the risks of urinary tract infection and urethral trauma associated with catheterization, and is a critical first step in evaluating urinary retention, with PVR >50-100ml suggesting significant retention 1
Abdominal ultrasound provides a non-invasive method to assess bladder function, prostate abnormalities, and rule out other significant pathologies, including detecting potentially serious conditions such as renal carcinomas, abdominal aortic aneurysms, and urinary tract calculi 1

Alpha-adrenergic receptor antagonists (alpha-blockers) may be beneficial for urinary symptoms in patients with confirmed BOO, while treatment for those with detrusor overactivity without obstruction should focus on bladder retraining and potentially anticholinergics, as recommended by the American Urological Association 1
Addressing constipation is essential, as treatment of constipation alone can result in significant improvement in urinary symptoms, according to the American Gastroenterological Association 7
The American Heart Association recommends consideration of removal of indwelling catheters within 48 hours to reduce infection risk, and use of silver alloy-coated catheters if catheterization is necessary, in acute stroke patients 3

In women with pelvic organ prolapse, PVR should be measured with and without reduction of the prolapse to assess its impact on voiding function, as recommended by the American Urological Association 1
For patients with neurological conditions, PVR assessment should be part of both initial evaluation and ongoing follow-up, as recommended by the American Urological Association 1
For patients with recurrent urinary tract infections, PVR measurement is essential to rule out incomplete emptying as a contributing factor, as recommended by the American Urological Association 8
Detrusor underactivity is diagnosed in 11-40% of men with lower urinary tract symptoms (LUTS) related to chronic prostatitis, and should be distinguished from other causes of LUTS, according to the European Association of Urology 9
Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) may present with similar symptoms but different urodynamic findings compared to chronic bacterial prostatitis, and should be diagnosed and treated accordingly, as stated by the American Urological Association 10

In patients with impaired storage parameters that place upper tracts at risk, repeat urodynamic studies should be performed at appropriate intervals following treatment, with an interval of two years or less being reasonable once pressures have been normalized 6
A single elevated PVR should not be used alone to make treatment decisions, as there can be significant variability, and PVR cannot differentiate between obstructive and non-obstructive conditions by itself 1
The initial workup for sudden onset urinary retention and incontinence should include assessment of bladder residuals, urinalysis, and evaluation for neurological causes, as recommended by the American Urological Association 11, 1