Clinical characteristics and useful signs to differentiate detrusor underactivity from bladder outlet obstruction in men with non-neurogenic lower urinary tract symptoms

Abstract

Objective: To investigate the clinical characteristics and useful signs to differentiate detrusor underactivity from bladder outlet obstruction in men with non-neurogenic lower urinary tract symptoms.

Methods: A total of 638 treatment-naive men with non-neurogenic lower urinary tract symptoms who underwent subjective and objective evaluations were reviewed retrospectively. We divided the patients into detrusor underactivity and bladder outlet obstruction groups based on urodynamic findings, and compared parameters obtained from questionnaires and non-invasive tests. Detrusor underactivity was defined as bladder contractility index ≤100 and bladder outlet obstruction index ≤40, whereas bladder outlet obstruction was defined as bladder contractility index >100 and bladder outlet obstruction index >40.

Results: Of 638 patients, 145 (22.7%) had detrusor underactivity and 273 (42.8%) had bladder outlet obstruction. Total international prostate symptom score and international prostate symptom score-voiding subscore were significantly higher in the detrusor underactivity group. There were significant differences in prostate volume, intravesical prostatic protrusion, and all uroflowmetry parameters between the two groups. In multivariate logistic regression analysis, lower intravesical prostatic protrusion (cut-off value 8.2 mm), lower bladder voiding efficiency (cut-off value 70%), and the presence of sawtooth and interrupted waveform on uroflowmetry were significant predictive factors for detrusor underactivity. In particular, the incidence of sawtooth and interrupted waveform was significantly higher in the detrusor underactivity group (80%) than in the bladder outlet obstruction group (12.8%), which showed both high sensitivity (80%) and specificity (87.2%) in differentiating detrusor underactivity from bladder outlet obstruction.

Conclusions: Sawtooth and interrupted waveform on uroflowmetry can be a useful predictive factor for detrusor underactivity. In addition, lower intravesical prostatic protrusion and bladder voiding efficiency can be of supplementary use.

Keywords: bladder outlet obstruction; detrusor underactivity; lower urinary tract symptoms; underactive bladder; urodynamics.