Summary of the Urodynamics Workshops on IC Kyoto, Japan

Urodynamics has traditionally played a valuable role in the diagnostic evaluation of patients with irritative bladder symptoms. The investigation allows the clinician to distinguish the oversensitive bladder (interstitial cystitis) from the overactive bladder (detrusor overactivity or instability). The importance of urodynamics was exemplified by the NIDDK consensus committee on interstitial cystitis (IC) who included cystometry as an essential diagnostic tool in selecting patients for clinical trials related to IC.1 However, since then, as a wider choice of more effective medical therapies for urgency, frequency, and even urge incontinence have become available, there has been a shift away from urodynamics as a first-line investigation of these patients and a move towards empiral treatment on the basis of symptoms alone. This appears to be the case in interstitial cystitis (IC) also.2 The author, who moderated the urodynamics workshops, made the case for using cystometry in the diagnostic workup of all patients suspected of having IC. The main aim of urodynamics is to exclude detrusor overactivity (DO) as the cause of the patient's symptoms. Filling cystometry also allows for an assessment of the patient's pelvic pain and how this relates to bladder filling while a voiding study allows an assessment of voiding pressure, which may be elevated in the case of bladder outlet obstruction or dysfunctional voiding. The place of urodynamics in the author's diagnostic algorithm is well-defined, being employed in those patients with typical symptoms (pelvic pain, urinary frequency, nocturia, and urgency), who have sterile urine (on repeated urine cultures) and who have typical frequency–volume records showing 1–2 hourly frequency when awake, nocturia (at least once) and functional bladder capacities less than 400 mL.3 The importance of the frequency–volume record should not be underestimated. Filling cystometry is performed in the manner described by the International Continence Society, with the bladder being filled on top of any immediate postvoid residual using normal saline at a filling rate of 50–60 mL/minute.4 The aim is to fill the bladder to at least the patient's functional bladder capacity and to reproduce the symptoms of which the patient complains. The volume at first urge (‘first sensation’) is recorded; ideally this should be less than 150 mLs in the case of bladder hypersensitivity (although the author recognizes that this is a rather variable and subjective parameter). Detrusor overactivity is actively sought during the filling phase by getting the patient to cough or stand and the filling phase ideally ought not to finish until the patient's bladder has been filled to at least his or her functional bladder capacity. This is recorded as the cystometric bladder capacity. Throughout the filling phase the clinician can observe the relation, if any, between steady bladder filling and the patient's experience of bladder or pelvic pain as well as any association with clinical events (urgency or incontinence). In this algorithm one may therefore determine whether a patient's symptoms are due to bladder hypersensitivity or to detrusor overactivity (1, 2). Filling and voiding cystometry in a 38-year-old lady with pain, frequency, and urgency, who has a functional bladder capacity of 160 mL. She has a hypersensitive (first sensation at 53 mL), stable bladder with a cystometric capacity of only 219 mL. Filling and voiding cystometry in a 40-year-old lady with pain, frequency, and nocturia who had a functional bladder capacity of only 90 mL. Her bladder was stable during the filling phase (filled to 65 mL only), but two large end-filling phasic detrusor contractions were provoked prior to voiding (detrusor overactivity). If detrusor overactivity is identified on the cystometrogram, the author treats the patient as such, using anticholinergic agents such as tolterodine, trospium, or propiverine. The author recognizes however, that patients suspected of having IC can also have detrusor overactivity and that the presence of DO should not exclude a diagnosis of IC. Indeed, the interstitial cystitis database study confirmed that approximately 14% of IC patients have overactive detrusors.5 If the patient's symptoms persist despite use of anticholinergics, he then proceeds to cystoscopy under general anesthesia. If the voiding phase of the urodynamic study shows evidence of bladder outlet obstruction then sphincter electromyography (EMG) studies may be required. There are limitations to urodynamics however, and these were discussed individually during each workshop: Should cystometry be used in the diagnostic workup of all patients or should it be confined to research studies? If DO is found on filling cystometry, does this imply that the patient cannot have IC? If no DO is found, despite provocation and filling to at least the functional capacity, does this mean that the patient always has a stable bladder? Is there a role for ambulatory urodynamics? Just what is ‘bladder hypersensitivity’? We tend to define it as a first sensation of urgency at a bladder volume less than 150 mL. However, this is a very subjective parameter and is influenced greatly by patient anxiety in the totally unnatural environment of the urodynamics lab. Is there a way of making ‘first sensation’ more objective or meaningful? Does the potassium sensitivity test have a role here? What about dysfunctional voiding and the bladder outlet? Should sphincter EMGs be an integral part of the urodynamic investigation of these patients? It was widely agreed that DO and IC can coexist and that the presence or absence of DO makes little difference to patient management. It appeared that the vast majority of delegates do not employ urodynamics as a routine investigational tool but rather treat their patients on the basis of symptoms alone (or on the basis of symptoms plus the findings from one or two further investigations). The general consensus from all three workshops was that urodynamics are not necessary in the routine evaluation of patients suspected of having IC. Only three of the workshop delegates (all European) employed urodynamics routinely in all their patients (Drs Wyndaele, Cervigni, and the author). The main argument against the routine use of urodynamics is that the majority of patients are treated on the basis of symptoms alone and that the presence or absence of DO makes little difference to the use of anticholinergic medication as a first-line therapy. An interesting concession was proposed by several delegates, namely that those clinicians who routinely employ urodynamics as part of their standard diagnostic workup of IC cases should continue to do so. This would not only allow one to maintain experience in this area but would also provide potential research data into detrusor function and bladder sensitivity in the long term. Most delegates agreed that male patients and those patients with concomitant urinary incontinence ought to have urodynamics as part of their diagnostic evaluation because bladder outlet obstruction and detrusor overactivity are important conditions to be excluded and treated. Failure to respond to standard treatment was also considered to be a justifiable indication for formal urodynamic investigation. It is recognized that conventional cystometry may underdiagnose detrusor overactivity in as many as 50% of cases where it has been detected using ambulatory monitoring.6 The general consensus was that ambulatory urodynamic monitoring is relatively specialized and ought to be employed only for specific research projects. Nonetheless, the author made the point that if detrusor overactivity is deemed to be an important (and far more prevalent) cause of symptoms than bladder hypersensitivity, ambulatory monitoring ought to be investigated more in this group of patients. Pelvic floor dysfunction may occur quite commonly in association with IC and good therapeutic responses have been reported from techniques such as biofeedback and neuromodulation, which provide for pelvic floor/external sphincter relaxation.7,8 While Drs Wyndale and Cervigni argued that pelvic floor dysfunction should be investigated in all potential IC cases, the general consensus was that EMG studies were too complex to be employed in routine clinical work-up and ought to be reserved for patients with symptoms of or cystometric evidence of bladder outlet obstruction. As in the case of ambulatory urodynamics, sphincter EMGs were considered to be worthwhile investigation tools in refractory or difficult cases but ought only to be used in specialized units. This provoked an observation from the author that by demoting urodynamics to second-line investigation and research, we may be in danger of deskilling from the point of view of this important diagnostic modality. There were several suggestions therefore that those clinicians who currently employ urodynamics routinely should continue to do so, despite the fact that the presence or absence of DO should not make any difference to diagnosis or management. This could potentially create even more confusion in the future as two separate groups of patients might emerge, those with IC in whom DO and sphincter problems have been actively excluded and those with IC who might also have DO or dysfunctional voiding due to sphincter problems. Many suggested that a frequency–volume record might be used in place of a routine urodynamic study as it would provide evidence of daytime frequency, nocturia, and functional bladder capacity. However, there was a general agreement that no limits should be set to individual parameters. The frequency–volume record would also be valuable in patient follow-up. Dr Diokno stated that there are strong correlations between frequency, nocturia, and functional bladder capacity and the findings on urodynamics, a point exemplified in a presentation made by Dr Takei.5 Once again, there was a general consensus that patients should not be excluded from research trials simply because they have not had a urodynamic study or, where it has been done, because they have DO. Several attendees, Dr Nickel in particular, suggested that urodynamics should be recommended only in situations where a specific question needed to be addressed. Precisely what sort of questions these might include was not clarified. The author strongly recommended that the crucial question was whether IC (bladder hypersensitivity) and DO were distinct pathological entities or whether they are part of a neurourological continuum. If as clinicians, or more importantly as researchers, we seek to make this distinction, and then perhaps ambulatory urodynamic studies are required, as this modality will pick up 50% of cases missed by conventional urodynamics.6 Only a handful of delegates had direct clinical experience with the potassium sensitivity test as a diagnostic tool. There was some divergence of views concerning its value. Dr Parsons felt that a positive test was diagnostic of IC, while the majority of those who had some (albeit considerably less than that of Dr Parsons) experience felt that its role was limited. Dr Nickel stated that 80–90% of patients with symptoms of pain, frequency, and urgency are test positive, but that test-positivity is not specific to IC. A Canadian study also failed to find any correlation between the potassium test and either bladder capacity or cystoscopic findings.9 Dr Sant felt that everyone with an interest in IC should employ the potassium sensitivity test in order to evaluate its usefulness. A: The majority of delegates felt that: Routine urodynamic investigation has no role in the diagnostic work-up of patients suspected of having IC. Urodynamics should be reserved for special cases, which include i) male patients. ii) patients with associated urinary incontinence. iii) patients whose symptoms remain refractory to standard therapy. iv) research, but only to answer specific questions. Frequency–volume records should be used more widely, both for diagnosis and follow-up, but no limits should be placed on number of voids, nocturia, or functional capacity. Those who routinely use urodynamics in diagnosis should continue to do so. B: There was a clear difference of opinion as to the value of urodynamics between European delegates (favoring routine use) and those from non-European countries (who felt that urodynamic investigation had a minor role, if any). C: Isolated strong cases were made in support of: Widespread use of the potassium-sensitivity test to evaluate its usefulness in diagnosis. Routine use of sphincter EMGs to evaluate pelvic floor function. Further research to determine whether detrusor overactivity and bladder hypersensitivity are discrete entities or part of a continuum.

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