Defining the Degree of Intravesical Prostatic Protrusion in Association With Bladder Outlet Obstruction

Abstract

PurposeThe present study was done to define the degree of intravesical prostatic protrusion (IPP) causing bladder outlet obstruction (BOO) in patients with benign prostatic hyperplasia (BPH)/lower urinary tract symptoms.Materials and MethodsWe retrospectively evaluated 239 patients with BPH, analyzing age, IPP, prostate volume, International Prostate Symptom Score (IPSS), and the results from a pressure-flow study. Urethral resistance was quantified by using the BOO index (BOOI), according to the formula BOOI=PdetQmax-2×Qmax (where Pdet is detrusor pressure at the peak flow rate and Qmax is peak flow rate). BOO was defined by a BOOI above 40. Patients with a BOOI below 20 were excluded. Patients were classified into two groups (obstructed and unobstructed groups) by the BOOI. Correlations were determined by logistic regression analysis, and receiver operating characteristic curves were plotted to estimate the optimal cutoff for IPP.ResultsThere were significant differences in total prostate volume, postvoiding residual urine (PVR), IPP, and Qmax (p<0.001, p<0.001, p<0.001, and p=0.026, respectively) between the obstructed and unobstructed groups, but there were no significant differences in age (p=0.653), IPSS total score (p=0.624), or quality of life score (p=0.138). IPP had a significant prognosis (p<0.001) but was weakly correlated with prostate volume (p=0.026). The correlation coefficients between IPP and Qmax, PVR, prostate volume, and BOO were 0.551, -0.159, 0.225, and 0.391, respectively. For IPP, the area under the curve was 0.759 (95% confidence interval, 0.657 to 0.861) and the cutoff to indicate BOO was 5.5 mm with 66.7% sensitivity and 80.5% specificity.ConclusionsAn IPP exceeding 5.5 mm was significantly associated with BOO.

Combination of intravesical prostatic protrusion and resistive index is useful to predict bladder outlet obstruction in patients with lower urinary tract symptoms suggestive of benign prostatic hyperplasia

“…In addition, TPV is not a useful predictor, because the AUC of TPV is lower than that of IPP. These findings agree with previous studies …”

“…The present results also showed that IPP is a better predictor of BOO than other parameters, with a sensitivity, specificity, PPV, and NPV of 75.0%, 75.3%, 76.2% and 74.0%, respectively. Although other researchers have proposed other cut‐off values for IPP, the differences in cut‐off values might be caused by differences in the patient populations …”

“…These findings agree with previous studies. [13][14][15][16][17][18][19][20][21] Because of the inability to predict BOO by TPV alone, morphological approaches to the prostate have been investigated to predict BOO. TZ is one of the three zones of the prostate, and is the main site of the origin of prostate hyperplasia.…”

“…Although other researchers have proposed other cut-off values for IPP, the differences in cut-off values might be caused by differences in the patient populations. 17,18,21 RI is an indicator of vascular resistance. 28,29 For predicting BOO, Kojima et al reported that the RI of the prostatic blood supply was significantly higher in patients with infravesical obstruction than in those without, and that RI and urodynamic parameters obtained in pressure flow studies were significantly correlated.…”

Clinical Considerations for Intravesical Prostatic Protrusion in the Evaluation and Management of Bladder Outlet Obstruction Secondary to Benign Prostatic Hyperplasia

“…In a 2015 study, postoperative changes in IPSS and QoL score were higher in the significant IPP group (IPP ≥ 5 mm) than in the group with no significant IPP (IPP < 5mm) [36]. Another study demonstrated that IPP ≥ 5.5 mm was significantly associated with BOO [37]. Early detection of IPP by TRUS will obviate the delay encountered by refractory pharmacological response.…”