DETRUSOR CONTRACTION DURATION AS A URODYNAMIC PARAMETER OF BLADDER OUTLET OBSTRUCTION FOR EVALUATING MEN WITH LOWER URINARY-TRACT SYMPTOMS

Purpose: Recent studies suggest that detrusor contraction duration inc reases with bladder outlet obstruction and correlates with the America n Urological Association (AUA) symptom index. Since the detrusor contr action duration may also depend on detrusor contractility and bladder volume, its use alone in characterizing bladder outlet obstruction is debatable. Therefore, we studied the relationship between detrusor con traction duration and bladder outlet obstruction, bladder capacity, de trusor contractility and symptoms to determine whether detrusor contra ction duration is a useful parameter for characterizing bladder outlet obstruction in men with lower urinary tract symptoms. Materials and M ethods: Pressure-flow studies were performed in men with lower urinary tract symptoms. Bladder outlet obstruction was defined as passive ure thral resistance relation greater than grade II and contractility was determined from Schafer's nomogram. Detrusor contraction duration was defined as the contraction time elapsed between the first rise in detr usor pressure from baseline to the time at which detrusor pressure ret urned to baseline at the end of voiding. AUA symptom index was attaine d from each patient and categorized as mild (0 to 7), moderate (8 to 1 9) and severe (20 to 35). Results: Detrusor contraction duration was d etermined from 58 consecutive pressure-flow studies. This parameter wa s not significantly different among 23 patients with mild (116.7 +/- 3 4.0 seconds), 15 with moderate (102.7 +/- 61.9 seconds) and 9 with sev ere (89.2 +/- 44.4 seconds) AUA symptom index scores. AUA symptom inde x, as well as irritative and obstructive scores did not significantly correlate with detrusor contraction duration. Detrusor pressure at max imal flow was weakly correlated with detrusor contraction duration (r = 0.322, p = 0.014). However, detrusor contraction duration in 27 obst ructed patients (111.6 +/- 53.7 seconds) was not significantly differe nt from that of 31 nonobstructed patients (91.5 +/- 41.5 seconds) and it did not increase with the severity of bladder outlet obstruction. D etrusor contraction duration in 40 patients with good contractility (9 4.3 +/- 49.2 seconds) was significantly lower than in 18 patients with poor contractility (115.5 +/- 43.3 seconds). Detrusor contraction dur ation was significantly lower in nonobstructed patients with good cont ractility (72.0 +/- 21.7 seconds) compared with either nonobstructed p atients with poor contractility (118.4 +/- 47.7 seconds) or obstructed patients with good contractility (112.5 +/- 58.0 seconds). There was no difference in detrusor contraction duration between nonobstructed p atients with poor contractility and obstructed patients with good cont ractility. Multiple regression analysis showed that detrusor contracti on duration can be best predicted by a combination of detrusor pressur e at maximal flow, bladder capacity and contractility (r = 0.576). Con clusions: Our study showed that detrusor contraction duration cannot d istinguish patients with from those without bladder outlet obstruction , and it does not correlate with the severity of symptoms. Since our r esults also showed that detrusor contraction duration depends an sever al factors related to detrusor and outlet function, it cannot be used as a reliable parameter to diagnose bladder outlet obstruction.