Prostate Volume Measurement by Transrectal Ultrasonography: Comparison of Height Obtained by Use of Transaxial and Midsagittal Scanning

PURPOSE The purpose of this study was to compare prostate volume measured by transrectal ultrasonography (TRUS) between transaxial scanning and midsagittal scanning. We tried to determine which method is superior. MATERIALS AND METHODS A total of 968 patients who underwent TRUS for diagnosis of any diseases related to the prostate were included in this study. When measuring prostate volume by TRUS, we conducted the measurements two ways at the same time in all patients: by use of height obtained by transaxial scanning and by use of height obtained by midsagittal scanning. Prostate volume was calculated by using the ellipsoid formula ([height×length×width]×π/6). RESULTS For prostate volume measured by TRUS, a paired t-test revealed a significant difference between using height obtained by transaxial scanning and that obtained by midsagittal scanning in all patients (28.5±10.1 g vs. 28.7±9.9 g, respectively, p=0.004). However, there were no significant differences in the prevalence of prostate volume more than 20 g (known benign prostatic enlargement [BPE]) between the two methods by chi-square test (90.5% [n=876], 90.8% [n=879], respectively; p=0.876). When analyzed in the same way, there were no significant differences in the prevalence of prostate volume more than 30 g (generally, high-risk BPE) between the two methods (34.5% [n=334], 36.3% [n=351], respectively; p=0.447). CONCLUSIONS Although prostate volume by TRUS differed according to the method used to measure height, that is, transaxial or midsagittal scanning, we conclude that there are no problems in diagnosing BPE clinically by use of either of the two methods.