Analysis of the pathophysiology of lower urinary tract symptoms in patients after prostatectomy

OBJECTIVES: To analyze the pathophysiology of persistent lower urinary tract symptoms (LUTS) in patients after transurethral prostatectomy (TURP). METHODS: A total of 185 patients who had persistent LUTS after TURP were enrolled into this study. All of these patients underwent multichannel videourodynamic studies and were classified into 6 groups according to the urodynamic results. Preoperative prostate volume, resected adenoma weight, and preoperative Q(max) were determined in each of the groups and the symptomatology and urodynamic findings were compared. RESULTS: A normal videourodynamic tracing was found in 17 patients (9.1%), pure detrusor instability in 18 (9.6%), low detrusor contractility in 35 (18.7%), detrusor instability and inadequate detrusor contractility (DHIC) in 27 (14.4%), poor relaxation of the urethral sphincter in 36 (19.3%), and bladder outlet obstruction (BOO) in 52 (27.8%). Incontinence was noted in 74 patients (40%), and 18 of them had BOO (24.3%). In urodynamic findings, Q(max) and residual urine showed no significant difference among patients with low contractility, poor relaxation of sphincter, DHIC and BOO. Concerning the preoperative prostatic volume, patients with low contractility, poor relaxation of urethral sphincter, and DHIC had a nonsignificantly smaller prostate volume and resected prostate weight than other groups. Preoperative Q(max) showed no significant difference among all groups. CONCLUSIONS: Symptoms alone are unreliable in predicting urodynamic findings with respect to obstruction and detrusor instability after TURP. Over half of the patients with persistent LUTS had a small prostate volume and small resected adenoma weight, indicating that some of these patients may not have had BOO. Videourodynamic study is helpful in making an accurate diagnosis for refractory LUTS after TURP.