Detrusor contraction strength in men undergoing prostatectomy.

Elective prostatectomy is a frequently performed operation but the outcome may not always be satisfactory. This is probably because a significant number of men, despite subjective symptoms, are not urodynamically obstructed before operation and the preoperative assessment of obstruction is not easy using conventional urodynamic criteria. We have calculated detrusor contraction strength (WF) in men before and after prostatectomy. Our aim was to determine its relationship with symptomatic and urodynamic findings before and after prostatectomy and whether it was associated with clinical outcome. One hundred and twenty nine men listed for operation because of symptoms and low urinary flow rates were studied by means of urodynamic investigation and symptom scoring both before and 6 months after prostatectomy. A significant association was found between persistent obstructive symptoms after operation and a low WF before operation (P = 0.01), suggesting that weak detrusor function before operation was the cause of persistent symptoms afterwards. A significant correlation was also found between a high pre-operative WF and a high post-operative urinary flow rate; (P = 0.003); men with high detrusor power achieving the better flow rates after operation. Despite this relationship, the overall subjective clinical outcome was not strongly associated with WF and WF was no better than simple measurement of voiding pressure in predicting outcome in a multivariate analysis. The measurement of detrusor contraction strength provides some insight into the relationship between bladder function and clinical outcome after prostatectomy, but we have found it unable to predict outcome for the individual patient.