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

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.