Urodynamic investigations are used to investigate bladder function and dysfunction in women with urinary symptoms, the most common being urinary incontinence. Guidance from the National Institute for Health and Clinical Excellence covers much of when investigations should be performed. Women are often anxious and embarrassed when they attend the tests. Recognition of the artificial test conditions and the feelings of the woman are crucial to optimising the chances of reproducing symptoms. Before cystometry, written information explaining the test should be provided with the appointment letter or when the woman attends the clinic. The information should include instructions on providing a urine sample in a sterile container, bladder chart and questionnaires and advice to come with a comfortably full bladder. Women who are using drugs to treat lower urinary tract dysfunction should normally stop using the medication for an appropriate period of time before the investigation.

Urodynamic equipment varies in complexity and a range of urodynamics machines. External pressure transducers are mounted on the urodynamic equipment and connected to the fluid-filled lines. A fluid-filled pressure catheter is placed in the bladder to measure intravesical pressure, and a second catheter is inserted into the rectum or the vagina to measure intra-abdominal pressure. Solid-state catheters with a single-tip transducer inserted into the rectum and covered with a condom, sheath or gloved finger, can be used to measure intra-abdominal pressure. Setting up can be considered as connecting the transducers and filling line and setting zero pressure. The calibration of solid-state catheter-tip transducers should be checked regularly. This requires that the transducers are immersed to a set depth in water, rather than raised in air, or by means of a special calibration chamber which is capable of generating pressures in centimetres of water.

Flow rate testing is a simple, non-invasive test, which can provide useful clinical information. The two most common flow rate measurement systems are gravimetric and rotating disc. This chapter discusses preparation and procedures for performing the flow rate testing and clinical cases of the flow rate testing. The flow rate machine should be in a private area. The patient should be well hydrated and prepared to wait for as long as needed to obtain an adequate result. The patient is instructed to void normally in their normal voiding position. Post-void residual urine volume (PVR) is measured within 10 minutes of voiding. Low Qmax may be associated with voiding dysfunction after continence surgery or pelvic organ prolapse. A high PVR may occur infrequently after anticholinergic drug administration in overactive bladder syndrome. Low Qmax can also result from bladder outlet obstruction. Elevated PVR can occur in conjunction with detrusor failure.

Cystometry is the measurement of pressures inside the bladder both during the storage phase and the voiding phase of urodynamics. Post-void residual urine is assessed prior to cystometry by a dedicated bladder scanner, conventional ultrasound scanner or via inserting and draining the residual urine through the urethral filling catheter. Cystometry is usually postponed if the patient has a urinary tract infection because this could influence the urodynamic findings. The bladder diary provides a good idea of the patient's normal functional bladder capacity, and is helpful in conducting the cystometrogram. Detrusor overactivity describes involuntary detrusor contractions occurring during the filling phase of cystometry. The International Continence Society defines urodynamic stress incontinence as urinary leakage seen during filling cystometry in the presence of raised abdominal pressure but in the absence of a detrusor contraction. Leakage seen during coughing while the cystometric trace shows no evidence of a detrusor contraction confirms the diagnosis.

Videocystourethrography (VCU) uses iodine-based contrast rather than 0.9% physiological saline, to allow simultaneous imaging of the lower urinary tract during urodynamic assessment. In addition to equipment for conventional cystometry, it is necessary to have a fluoroscopy unit with a high-resolution image intensifier and a tilt table. Fluoroscopic images can be obtained selectively during the filling and voiding study. VCU allows accurate visualisation of the functional anatomy of the lower urinary tract. It enables classification of urinary stress incontinence into four types (0-3), although this classification is no longer commonplace. In patients with neurogenic bladder, VCU provides a more complete assessment, including identification of vesicoureteric reflux during filling or voiding phase and, in some patients, it may visualise detrusor sphincter dyssynergia. VCU will enable visualisation of anatomical abnormalities such as bladder or urethral diverticulae or fistulae and bladder herniation. Although rare in women, it may allow identification of bladder outlet obstruction.

Ambulatory urodynamic monitoring (AUM), using micro-tip pressure transducers and a digital solid-state recorder, 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. This system allows information to be recorded digitally, downloaded and reviewed at the end of the test. AUM is performed in accordance with the International Continence Society (ICS) Standardisation of Ambulatory Urodynamic Monitoring. The care and observation of a patient undergoing AUM is as important in the diagnosis as the objective measurements and neither should be carried out in isolation. Checks on signal quality are highly important at the start, during the test and again before the test terminates. AUM has a role in monitoring voiding function. It allows women to pass urine in a flowmeter in a private setting as and when they desire.

Artefacts during uroflowmetry may arise owing to several factors, which can be broadly classified into two groups: extracorporeal and intracorporeal. Recommendations to minimise uroflowmetry artefacts include ensuring privacy, checking the report and tracing immediately, correcting artefacts manually and checking that the void was representative of normal. Initial quality checks will prevent the majority of artefacts. Artefacts may arise during the voiding phase owing to displacement of the vesical or rectal pressure transducer or inadequate pressure transmission. Artefacts are spurious and inaccurate urodynamic observations. Artefacts at uroflowmetry are minimised by checking calibration regularly and asking the patient to void normally in private. Artefacts during cystometry can be minimised by zeroing transducers to atmospheric pressure, expelling air bubbles and checking for good subtraction with cough testing before filling, at 1-minute intervals during filling and before and after voiding.

This chapter discusses the tests of urethral function. The International Continence Society (ICS) has suggested standardisation of the performance of the urethral function and defined parameters for measurements. Two tests may be included to assess urethral function specifically during filling cystometry: vesical or detrusor leak-point pressure estimation and abdominal leak-point pressure (ALPP). Tests of urethral function during voiding cystometry measure the relationship between pressure in the bladder and urine flow rate. Urethral pressure profilometry (UPP) provides a graph indicating the intraluminal pressure along the length of the urethra. Urethral retro-resistance pressure (URP) has been defined as the pressure required to achieve and maintain an open urethral sphincter. Urethral pressure reflectometry (UPR) is measured using a 5-mm diameter polyurethane bag and urethral transducer. Tests of urethral function may also be useful in identifying incompetent urethral closure mechanisms before obstructive surgery for stress urinary incontinence.

The bladder diary is an important tool in the investigation of patients with lower urinary tract symptoms and voiding dysfunction. There are different methods for recording information on voiding patterns. A frequency-volume chart is the simplest method and collects information on volumes voided and micturition times. A voiding or bladder diary provides a more detailed record. The paper diary is the most common as it is easy to produce and store, inexpensive and convenient to post or hand directly to the patient. The electronic bladder diary such as the UroDiary uses an intelligent character recognition programme and calculates a centile ranking for results, correcting for age and 24-hour voided volume. Bladder diaries are more accurate than recall when recording urinary symptoms. The bladder diaries guide many aspects of conservative treatment, especially timing and types of fluids.

Pad testing is most often used in the objective assessment of women with urinary incontinence. It involves the use of pre-weighed continence pads to capture urinary leakage over a period of time. The pads are then weighed to calculate the amount of leakage on completion of the test. The two most common methods used for pad testing are 1-hour and 24-hour tests. One-hour pad tests are performed in a clinical setting, under the supervision of a continence nurse or doctor. Twenty-four-hour tests are performed at home. Women are provided with a set of pads and advised not to modify their normal drinking or activities. The ICS Standardisation Committee has set out a standard protocol for the 1-hour pad test. Pad tests are of most value in the research setting before and after treatment, as an objective endpoint of urinary incontinence. Women's compliance with 24-hour pad tests decreases once cured.

The King's Health Questionnaire (KHQ) is a condition-specific, self-completion questionnaire. The KHQ has been extensively used in pharmaceutical clinical studies. The National Institute for Health and Clinical Excellence (NICE) has recommended use of the KHQ in the assessment of women with lower urinary tract symptoms. The KHQ measures nine domains of quality of life: general health perception, incontinence impact, social limitations, role limitations, physical limitations, personal relationships, severity measures, sleep/energy and emotions. The electronic personal assessment questionnaire to measure, process and present pelvic floor symptoms and their impact on quality of life (ePAQ-PF) was originally derived from paper-based instruments. ePAQ's urinary dimension provides scores for stress urinary incontinence, overactive bladder, voiding, pain and quality of life. The International Consultation on Incontinence Modular Questionnaire (ICIQ) was developed to provide a universally applicable, standardised series of self-completion assessment instruments to evaluate lower urinary symptoms, lower bowel symptoms and vaginal symptoms.

Ultrasound of the bladder is used in clinical practice as a non-invasive estimate of bladder volume when assessing post-void urinary residual. Two types of ultrasound equipment are dedicated bladder scanner and standard linear array transabdominal or transvaginal ultrasound. Ultrasound of the bladder neck can be used to assess urethral hypermobility. Increased bladder neck mobility is associated with stress urinary incontinence. The volume of the urethral sphincter can be measured using three-dimensional ultrasound. Measurement of the thickness of the bladder wall has been validated using the transvaginal, transperineal, translabial or transabdominal approach. The ultrasound is likely to be used increasingly to provide the anatomical parameters in conjunction with functional parameters provided by urodynamics. Two-dimensional and three-dimensional ultrasounds have been employed to statically and dynamically image the pelvic floor. The application of ultrasound in the identification of levator injury is currently being used as a research tool.