Novel ultrasound-based volume estimation of prostatic benign enlargement to improve decision-making on surgical approach

Abstract

Aim: To assess the precision of preoperative ultrasonography (US)-determined prostate volume and to propose formulas for improving it. Methods: This retrospective study comprised 155 consecutive men who underwent open prostatectomy for benign prostatic hyperplasia (BPH) between 2013 and 2019. Preoperative prostate volume was estimated by either abdominal US (AUS) ( n = 92) or transrectal US (TRUS) ( n = 63), and was compared with the weight of surgically enucleated tissue at a conversion rate of 1 ml (US) = 1 g tissue. Statistical analysis was conducted and a novel formula for prostate volume was constructed. Results: The median prostate volumes by AUS and TRUS were 140 ml [interquartile ratio (IQR) 111–182] and 108 ml (IQR 93–120), respectively. Enucleated tissue weight was lower than the AUS assessment by a median difference of 50 g (IQR 28.7–75.7; p < 0.001), and lower than the TRUS assessment by a median difference of 27 g, IQR 10–43, p < 0.001). Using a cutoff of 80 ml, 30 (33%) AUS patients and 23 (36%) TRUS patients underwent unneeded open procedures. Mathematical calculations revealed two formulas that significantly adjusted for the actual weight: 1.082*Age + 0.523*AUS − 53.845 for AUS and 0.138*age + 2.22*prostate-specific antigen + 0.453*TRUS + 11.682 for TRUS ( p < 0.001). These formulas increased the overall US prostate volume accuracy from 65% to 85%. Conclusion: Assessment of prostate volume by US is imprecise for decision-making of whether to perform open simple prostatectomy for BPH. Our novel formulas may enhance stratification of patients with prostatic enlargement to a more optimal surgical approach. Future studies in larger cohorts are needed to substantiate our results.