A Systemic Review and Meta-analysis of Transabdominal Intravesical Prostatic Protrusion Assessment in Determining Bladder Outlet Obstruction and Unsuccessful Trial Without Catheter

Urodynamic study (UDS) provides the most objective assessment of bladder outlet obstruction (BOO) but is impractical to be recommended routinely in outpatient services. Intravesical prostatic protrusion (IPP) had been described to obstruct urinary flow by creating an anatomical ball-valve effect, but there remains a lack of pooled evidence that can objectively correlate with BOO in benign prostatic hyperplasia. To update the current evidence on the predictive role of IPP in determining BOO and unsuccessful trial without catheter (TWOC). A comprehensive literature search was performed to identify studies that evaluated IPP in diagnosing UDS-determined BOO and TWOC. The search included the PubMed/MEDLINE, EMBASE, and Cochrane Library up to January 2021. An updated systemic review and meta-analysis was performed. A total of 18 studies with 4128 patients were examined. Eleven studies with 1478 patients examined the role of IPP in UDS-determined BOO. The pooled area under the curve (AUC) was 0.83 (95% confidence interval [CI]: 0.79–0.86), and at a cut-off of >10 mm, the sensitivity (Sn) and specificity (Sp) were 0.71 (95% CI: 0.61–0.78) and 0.77 (95% CI: 0.68–0.84), respectively. The probability-modifying plot revealed positive and negative likelihood ratios of 3.34 (95% CI: 2.56–4.36) and 0.35 (95% CI: 0.26–0.45), respectively. Seven studies with 2650 patients examined IPP in predicting unsuccessful TWOC, with a pooled AUC of 0.74 (95% CI: 0.70–0.84), with Sn of 0.51 (95% CI: 0.43–0.60) and Sp of 0.79 (95% CI: 0.73–0.84) at an IPP cut-off of >10 mm. Five studies compared prostate volume (PV) and IPP and revealed a lower AUC of PV at 0.71 (95% CI: 0.67–0.75), which was an inferior parameter in diagnosing BOO (p < 0.001). This systemic review provided evidence that IPP is a reliable clinical parameter that correlates strongly with underlying BOO and unsuccessful TWOC. In this review, we comprehensively reviewed all the literature to date on evaluating the clinical utility of intravesical prostatic protrusion (IPP). We have demonstrated that IPP correlates strongly with urodynamic study (UDS)-determined bladder outlet obstruction and failure of trial without catheter (TWOC). Outpatient IPP measurement is a quick, inexpensive, and reproducible clinical parameter that can determine the severity of benign prostatic hyperplasia. The clinical role of IPP in predicting failure of TWOC selects patients who are best treated with aggressive surgical approaches rather than