Determination of transition zone volume by transrectal ultrasound in patients with clinically benign prostatic hyperplasia: Agreement with enucleated prostate adenoma weight - Editorial Comment

Purpose: Accurately estimating transition zone volume is important for the medical or surgical management of symptomatic benign prostatic hyperplasia and determination of prostate specific antigen density of the transition zone. We evaluated whether preoperative transrectal ultra- sound measurements of the transition zone predict enucleated adenoma weight. Materials and Methods: We measured transition zone volume preoperatively using transrectal ultrasound and the prolate ellipsoid method in 50 patients with presumed benign prostatic hyperplasia who underwent suprapubic prostatectomy. Transition zone volume corresponds to the adenoma. Enucleated adenoma weight was then correlated with preoperatively determined transition zone volume. Results: As measured by transrectal ultrasound, mean transition zone volume plus or minus standard deviation was 80.88 ± 37.42 cc (range 31 to 200). Mean enucleated adenoma weight was 68.70 ± 36.26 gm. (range 18 to 180). There was a statistically significant correlation of estimated transrectal ultrasound volume of the transition zone with enucleated prostate adenoma weight (r = 0.95 p <0.001). However when prostate adenoma weight was determined using the formula prostate adenoma weight = -6.00 + 0.92 x transition zone volume we noted a significant difference in mean prostate adenoma weight and mean transition zone volume (p <0.001). Since the regression coefficient of transition zone volume was significantly different from 1, we identified no agreement of prostate adenoma weight with estimated transrectal ultrasound volume of the transition zone. Conclusions: These data reveal a significant difference in mean prostatic adenoma weight and mean transition zone volume. Although transition zone volume measurements are well described, clear agreements on such measurements should be obtained to determine transition zone volume more precisely.