Transurethral prostate resection in patients with hypocontractile detrusor: what is the predictive value of ultrastructural detrusor changes?

Purpose: Men with detrusor failure and chronic urinary retention have a lower voiding success rate and higher postoperative morbidity following transurethral prostatectomy than those with bladder outlet obstruction. Current investigations, including urodynamics, may be unable to predict the response to surgical treatment. We identified ultrastructural features on detrusor biopsy that correlated with the postoperative voiding outcome in patients with a hypocontractile detrusor undergoing transurethral prostatectomy.

Materials and Methods: Detrusor biopsies were obtained from 17 patients with urodynamic evidence of bladder outlet obstruction or a hypocontractile detrusor undergoing transurethral prostatectomy and from 5 controls. Specimens were examined by transmission electron microscopy. Ten individual detrusor ultrastructural features were analyzed. Findings were compared with preoperative and postoperative clinical parameters.

Results: Failure to void after transurethral prostatectomy was significantly associated with the ultrastructural features of variation in muscle cell size, muscle cell shape, collagenosis and abnormal fascicles. These 4 features were significantly associated with each other, defining a distinctive pattern of detrusor failure. For transurethral prostatectomy failure the sensitivity, specificity, and positive and negative predictive values of all 4 features together were 60%, 91%, 75% and 84%, respectively. Three or 4 features on detrusor biopsy predicted voiding failure.

Conclusions: Detrusor ultrastructural analysis is highly predictive of voiding outcome following transurethral prostatectomy in patients with detrusor failure. Patients with ultrastructural features previously described as part of the myohypertrophy pattern do not have a primary diagnosis of bladder outlet obstruction but rather detrusor failure secondary to bladder outlet obstruction.