Value of intravesical prostatic protrusion estimated by ultrasound in the diagnosis of bladder outlet obstruction and acute urinary retention in benign prostatic hyperplasia

Abstract

Objective This prospective study compared the sensitivity, specificity, and accuracy of intravesical protrusion of prostate (IPP), prostate volume (PV), detrusor wall thickness (DWT), and post-voiding residual urine (PVR) for diagnosis of bladder outlet obstruction (BOO) and predicted acute urinary retention (AUR) in patients with benign prostatic hyperplasia. Patients and methods Eighty patients of 50 years or older with obstructed lower urinary symptoms owing to prostate enlargement were included in this study. Of them, 20 patients presented with acute retention of urine. All patients underwent the following: international prostatic symptoms score, quality-of-life question, digital rectal examination, free uroflowmetry (Qmax), and transabdominal ultrasound, which measured DWT, PV, IPP, and PVR. Pressure flow study (PFS) was done to differentiate obstructed from the nonobstructed bladder. IPP, PV, DWT, Qmax, and PVR were used as index tests. To differentiate the effectiveness of these index tests, the area under the curve was calculated for each index. Results Eighty patients were classified into four groups according to their presentation and PFS finding: group I included 30 patients with no BOO [bladder outlet obstruction index (BOOI) 40), group III included 20 patients who presented with AUR, and group IV included 20 normal men as a control group. There were significant differences in PV, IPP, DWT, Qmax, and PVR between obstructed and nonobstructed patients, with a significant correlation with the BOOI. There was no significant difference regarding age and international prostatic symptoms score. There was a significant correlation between IPP and DWT with PFS in the diagnosis of BOO in patients complaining from benign prostatic hyperplasia. IPP more than 7.5 mm had the best accuracy (90.5%) in the diagnosis of BOO. IPP more than 7.5 mm and DWT more than 2 mm diagnosed acute retention of urine in 90% of patients. Conclusion IPP measurement is the best noninvasive test in detecting BOO in comparison with other index tests. Combined IPP and DWT were more accurate in predicted BOO and AUR than other index tests.