Urodynamics (UDS) is an interactive study of the lower urinary tract (LUT) that evaluates the transport, storage, and evacuation of urine. UDS is composed of a combination of tests that can be used collectively to obtain functional information about the LUT. The study can be divided up into two main phases: the storage (or filling) phase and the emptying (or voiding) phase. During the storage phase, cystometry is performed and includes measurement of bladder sensation, contractions, compliance, and capacity. Other tests, such as abdominal leak point pressure (ALPP) and detrusor leak point pressure (DLPP), can also be performed when indicated. The emptying phase consists of pressure flow studies and can give valuable information about voiding.
Collectively, the storage and emptying phases of UDS can be enormously helpful in providing objective sings to match an individual’s symptoms when the physical exam findings and other less invasive studies are inconclusive (Abrams et al, 2003). The purpose of UDS, in most cases, is to reproduce and objectively quantify a patient’s symptoms to better understand their underlying causes and to aid in diagnosis. In some cases, such as in patients with certain neurologic conditions, individuals may not experience symptoms and urodynamics may be necessary to ensure the safety of urine storage and emptying (Winters et al, 2012).
INDICATIONS FOR URODYNAMICS
Urodynamics should never be performed in isolation, but rather, should be employed when history and physical exam findings do not adequately diagnose or predict the pathophysiology of LUT complaints (Winters et al, 2012), or in cases when an individual has a neurologic condition (eg, spinal cord injury or multiple sclerosis) with a high risk for serious and irreversible upper and lower urinary tract complications.
Prior to each UDS, it is essential that there be a clear indication for the study and a specific clinical question that needs to be answered. Once the question is established, the study should be designed by selecting the appropriate tests to answer this question, and each study should be customized to the individual (Nitti and Combs, 1998). Studies should be performed on the basis of the following “good urodynamic practices”:
The clinician must have a clear indication for, and appropriate selection of, relevant test measurements and procedures.
There must be precise measurement with data quality control and complete documentation.
There must be accurate analysis and critical reporting of results (Schafer et al, 2001).
The American Urological Association (AUA) and the Society of Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction (SUFU) have published guidelines on urodynamics in adults and offer further guidance for appropriate use of UDS “to assist the clinician in the appropriate selection of urodynamic tests following an appropriate evaluation and symptoms characterization.” Their guidelines offer standards, recommendations, and options for the use of these studies in patients with stress-induced urinary incontinence and prolapse, overactive bladder, urgency urinary incontinence, ...