To investigate the accuracy of the bladder and prostate sonomorphologic parameters for the diagnosis of bladder outlet obstruction (BOO) in patients with lower urinary tract symptoms (LUTS)/benign prostatic hyperplasia (BPH).

First-visit men, aged ≥ 50 years, with LUTS/BPH were prospectively enrolled. Added to the initial basic evaluation, all patients underwent pelvic ultrasonography and pressure flow study. The pressure flow study was used as a reference standard for BOO, and according to its results, patients were divided into BOO and non-BOO groups. The sonomorphologic findings were compared between both groups, and the diagnostic accuracy of the significant parameters was determined.

In total, 157 patients were included. Of these, 48 (30.57%) had BOO and 109 (69.43%) did not. Bladder wall thickness (BWT), ultrasound estimated bladder weight (UEBW), and intravesical prostatic protrusion (IPP) were the sonomorphologic parameters that differed significantly between both groups (P < .001). By receiver operating characteristic curve analysis, the optimal cutoff values distinguishing patients with BOO were BWT of 3.7 mm (area under the curve [AUC]: 0.940), UEBW of 31.5 g (AUC: 0.835), and IPP of 10.9 mm (AUC: 0.874). The sensitivity, specificity, and accuracy of BWT, UEBW, and IPP were 95.00%, 90.91%, and 93.55%; 75.44, 57.97%, and 65.62%; and 87.90%, 76.43%, and 82.17%, respectively.

BWT, UEBW, and IPP measurements can be used to detect BOO in LUTS/BPH patients. The simple estimation of these sonomorphologic parameters by suprapubic approach makes these measurements potentially suitable methods to judge BOO noninvasively during the routine clinical evaluation of BPH.