ObjectiveTo assess the effect of the urodynamic catheter on the urinary flow rate and residual volume in various urodynamic diagnoses, and compare the outcome when using a smaller catheter, as the effect of this catheter on free uroflow variables is mostly studied in patients with bladder outlet obstruction (BOO) and little is known about its effect in other urodynamic diagnoses.Patients and methodsIn all, 319 men undergoing a pressure-flow study (PFS) with a 5 F filling and 5 F measuring bladder catheter were subdivided into three groups based on a urodynamic diagnosis, i.e. normal PFS (group 1), BOO (group 2) and detrusor underactivity (DU, group 3). Another group (4) comprised 61 patients who had a PFS with the filling catheter removed before the voiding phase. The effect of the catheters on the maximum urinary flow rate (Qmax) and the postvoid residual volume (PVR) was analysed statistically and compared among the groups. We also compared the free-flow variables with the clinical and urodynamic variables.ResultsGroups 1–3 (with two catheters) had a significantly lower Qmax and higher PVR than those voiding with one catheter (group 4). The reduction in Qmax was highest in group 3 (41.9%) and least in group 2 (21%). Group 4 showed no significant change in Qmax in cases with BOO and a normal PFS but a significant decline in those with DU (19.6%). The PVR was positively associated with the bladder capacity and negatively with detrusor contractility, but no association with a urodynamic diagnosis of BOO or any specific symptom.ConclusionDetrusor contractility was the strongest predictor of the obstructive effect caused by the catheter. This study justifies the use of a single 5 F catheter at the time of voiding, although that can also cause a reduction in flow in patients with DU.

Size of the external urethral meatus in adult Indian males is not yet documented. However, for choosing optimum size of an instrument, it is important to know the maximum stretchable external urethral meatal size in a particular patient. Hence, a prospective study was conducted at our institution to document the maximum stretchable adult male external urethral meatus size. After obtaining consent, 340 adult males who were undergoing urethral instrumentation for reasons other than the diseases of the urethra underwent urethral calibration using a "urethral calibrator" during February 2009 to April 2010. Data were analyzed using the SPSS 17. The average maximum stretchable external urethral meatal size in an Indian adult male was 28.49 Fr. Ours is the only study to document the maximum stretchable adult external urethral meatal size in Indian males which helps us for better instrumentation.

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INTRODUCTION:The effect of a transurethral catheter on urodynamic pressure-flow studies has been questioned, especially for patients with bladder outlet obstruction (BOO). The purpose of this retrospective study was to compare urodynamic outcomes measured during free uroflowmetry with pressure-flow studies using a transurethral catheter. METHODS:We retrospectively reviewed the records of 22 adult patients who had voided volume that did not differ by more than 20% during 2 assessments: free uroflow and pressure-flow with a transurethral 5 Fr catheter in situ. The outcome measures were maximum flow (Qmax), average flow rate, voiding time, time to Qmax, and flow acceleration. Free uroflow and pressure-flow outcomes were compared using paired t tests. A Bonferroni adjustment was applied; probability < .01 was considered statistically significant. RESULTS:There were 17 males and 5 females. The mean age was 39.9 years (range, 18-80 years). The urodynamic findings were reported as: normal (n = 6), hypocontractile detrusor (n = 5), BOO (n = 5), overactive bladder symptom complex (n = 4), and low pressure-low flow system (n = 2). Qmax was significantly higher during free uroflow than during pressure-flow recordings (P = .001). Average flow rate was also significantly higher during free uroflow (P < .001). Voiding time was significantly slower and acceleration was significantly faster during free uroflow (both with P = .001). There was no significant difference between recording conditions in the time to Qmax.CONCLUSION: There appears to be a significant decrease in some uroflow measurements with a 5 Fr urethral catheter in situ during pressure-flow studies, which is contrary to the previous claim that any catheter smaller than 6 Fr does not alter the results. This measurement artifact needs to be considered when interpreting urodynamic studies, particularly if the patient has BOO. To compensate for differences between the free uroflow rate and uroflow rate with a catheter, the free uroflow rate and detrusor pressure may need to be considered when evaluating the degree of BOO.UroToday International Journal ® UI J