Ultrasound detrusor wall thickness measurement in combination with bladder capacity can safely detect detrusor underactivity in adult men

Purpose Detrusor underactivity (DU) has lately gained increasing interest because this bladder condition is an important cause of post-void residual urine and lower urinary tract symptoms (LUTS) in adult men. Until now, DU can only be diagnosed by pressure–flow measurement. Therefore, the aim of this study was to search for noninvasive tests which can safely predict DU in adult men. Methods Unselected, treatment-naïve male patients aged ≥40 years with uncomplicated, non-neurogenic LUTS were prospectively evaluated. All men received—after standard assessment of male LUTS–ultrasound detrusor wall thickness (DWT) measurements at a bladder filling ≥250 ml and computer urodynamic investigation. DU was defined as incomplete bladder emptying (>30 ml) in the absence of bladder outlet obstruction or dysfunctional voiding. Classification and regression tree (CART) analysis was used to determine parameters and threshold values for DU. Results The study population consisted of 143 consecutive men with medians of 62 years, IPSS 16, and prostate volume 35 ml. In total, 33 patients (23.1 %) had DU. CART analysis showed that all men with DWT ≤ 1.23 mm plus bladder capacity >445 ml had DU. This multivariate model has a sensitivity of 42 %, specificity of 100 %, positive predictive value of 100 %, and negative predictive value of 85 %. Conclusions This study showed that all men with ultrasound DWT ≤ 1.23 mm + bladder capacity >445 ml have DU. Combination of these two tests could help physicians to diagnose DU noninvasively in clinical practice. A prospective independent study should confirm these results.