Conventional urodynamics (laboratory cystometry) is considered the ‘gold standard’ for measuring bladder function. However, it is a static short test, typically 20–30 minutes, and is considered ‘nonphysiological’. It involves rapid retrograde filling of the bladder in a laboratory setting, which does not always allow reliable reproduction of symptoms. Ambulatory urodynamic monitoring (AUM) relies on physiological bladder filling with natural stressors, including patient mobilisation over a longer time frame, to monitor bladder function which can then be directly compared to presenting symptoms. It is a useful additional test for women in whom conventional urodynamics fails to reproduce or explain the lower urinary tract symptoms of which they complain [1]. AUM is performed through a portable system which allows information to be recorded digitally, and downloaded and reviewed during or at the end of the test. The trace can then be expanded or compressed without loss of information.

A bladder diary provides an objective evaluation of the severity of urinary storage symptoms and associated urinary incontinence. Bladder diaries are not used to diagnose detrusor overactivity or urodynamic stress incontinence; however, they help to guide conservative management and to provide lifestyle advice, and keeping a bladder diary is the only method available to diagnose nocturnal polyuria.

Patient-centred questionnaires and patient-reported outcome (PRO) measures are terms that are used interchangeably to reflect an instrument that provides evaluation of the lived experience of symptoms from the patients’ perspective. PRO use has grown significantly in the past 10–15 years, due to recognition of the importance of placing patients at the centre of their care [1]. It is recognised that only those individuals experiencing symptoms can report on the more subjective elements [2]. This is particularly important in the case of urodynamics, which is a clinical test. PROs provide a method of measuring subjective phenomena in an objective way and provide context to the data provided by clinical measurements. PROs can be used to record the presence and severity of symptoms and also to measure their impact, in particular on quality of life. This is useful when interpreting patients’ priorities for treatment and understanding the most bothersome aspect of their symptoms.

Videocystourethrography (VCU), also known as videourodynamics, comprises synchronous radiological screening of the urinary tract during subtracted dual-channel filling and voiding cystometry [1].

According to the International Continence Society (ICS) (2016), cystometry is the continuous fluid filling of the bladder via a transurethral catheter (or other route, e.g. suprapubic or mitrofanoff), with at least intravesical and abdominal pressure measurements and display of detrusor pressure, including cough (stress) testing. Cystometry ends with ‘permission to void’ or with incontinence of the total bladder content [1].

The urethra is a complex organ essential for the maintenance of urinary continence. It has always been suggested that as long as the urethral pressure exceeds the one generated by the bladder, continence is maintained. This is a plausible explanation when the patient is at rest but cannot fully explain how this pressure differential is maintained during periods of raised intra-abdominal pressure.

Pad testing, most often used as an objective assessment of urinary incontinence, involves the use of pre-weighed continence pads to capture urinary leakage over a period of time. On completion of the tests, the pads are then weighed to calculate the amount of leakage.

Urodynamic equipment varies in complexity and a range of urodynamics machines are available. The choice of system depends on operator requirements. The Buyers’ Guide: Urodynamic Systems by Centre for Evidence-Based Purchasing may help to inform choice [1,2].

Data quality and documentation of variance are key for urodynamics studies to be valid, and symptoms must be reproduced to be able to make a diagnosis. Accurate reporting requires knowledge of pathophysiological parameters and the ability to detect artefacts. If inaccuracies are discovered, they should be corrected contemporaneously. Spurious and inaccurate observations are known as artefacts. The Oxford dictionary defines artefacts as something observed in a scientific investigation or experiment that is not naturally present but occurs as a result of the preparative or investigative procedure.’

VCU offers a comprehensive evaluation of the lower urinary tract by combining both anatomical and functional assessments.