Diagnostic values and limitations of conventional urodynamic studies (uroflowmetry.residual urine measurement.cystometry) in benign prostatic hypertrophy

Abstract

Diagnostic values and limitation of conventional urodynamic study (UDS) were assessed in 380 patients with benign prostatic hypertrophy (BPH), in terms of uroflowmetry, measurement of postvoid residual urine and cystometry. Maximum and average flow rate on uroflowmetry improved with increasing voided volume. Neither maximum nor average flow rate correlated with size of the prostate, subjective symptom (International Prostate Symptom Score) and bothersomeness for prostatism. Pre-TUR maximum flow rate did not predict outcomes on postoperative flow rate and surgical treatment failures. Uroflowmetry did not differentiate between obstruction and weakness of detrusor contraction. The intraindividual variation of postvoid residual urine was great and the volume of residual urine correlated poorly with subjective symptom, size of the prostate, maximum and average flow rate. On filling cystometry, although uninhibited detrusor contraction was much more frequently observed in patients with urge incontinence as compared with continent patients, there was no significant difference in other parameters between the two groups. Every parameter on cystometry did not correlate with nocturnal frequency. Postoperative persistence of urge incontinence did not correlate with the bladder volume at the first desire to void or at the maximum desire to void, an amplitude of uninhibited detrusor contractions, or bladder compliance. In some cases, evaluation of the intravesical pressure on voiding phase and uroflowmetry was diagnostic of apparent obstruction. In diagnosis of BPH, conventional UDS has limitation for certain and some caution showed be taken in interpretation of the data. However, since conventional UDS provides important and objective information on obstruction and detrusor function, which are independent of subjective symptom and prostate size, these should be necessary in diagnosis, determination of treatment options and evaluation of treatment outcomes in BPH.