Prostate volume measurement by suprapubic and transrectal ultrasonography in the assessment of benign prostatic hyperplasia patients: a cross sectional study.

Abstract

Title: Prostate volume measurement by suprapubic and transrectal ultrasonography in the assessment of BPH patients. Objective: To compare preoperative volumes of the whole prostate as measured by SPUS, TRUS and the correlation between preoperative volume and weight of enucleated adenoma of the prostate among patients with BPH. Methods: A Cross Sectional Study involving 50 patients who presented with symptomatic BPH and an IPSS> 20 with histological confirmation of BPH were included using a consecutive sampling. The volume of the whole prostate was estimated by a Radiologist using two modalities SPUS and TRUS on each patient during the same session. Open prostatectomy was done and the weight of the enucleated prostatic adenoma measured using an electronic weighing machine. Analysis included paired t test of means and mean of differences, sensitivity, specificity, positive and negative predictive values and Bland-Altman analysis of the degree of agreement between the two methods. Results: The mean age was 69.94 years (range 51 to 91). The mean volume of the prostate by SPUS and TRUS were respectively 95.89±51.38 ml and 95.98±51.55 ml. The mean of the differences between the prostate volume estimates by the two methods was 0.09 ml ( 95% CI: -2.07 to + 1.89 ) and was not statistically significant (p= 0.93).The correlation coefficient between preoperative volume of prostate estimates by SPUS and by TRUS was strong (r= 0. 98, p-value< 0.001). Bland and Altman analysis confirmed the strong degree of agreement between SPUS and TRUS. The sensitivity, specificity, positive and negative predictive values of the SPUS to detect prostate volume ≤ 80ml were both over 95%. The mean difference between the volume of the enucleated adenoma and the preoperative volume of the whole prostate estimated by SPUS and TRUS were 12. 39ml (95% CI: 7.89 16.88, p< 0.001) and 12.47ml (95% CI: -8.17 33.12, p< 0.001) respectively. Conclusion: The study has shown that SPUS is as accurate as the TRUS in assessing preoperative volume of prostate among symptomatic BPH patients. Suprapubic ultrasonography has excellent sensitivity and specificity for assigning patients to TURP relative to TRUS as gold standard. Suprapubic ultrasonography prostate volume estimates are highly correlated with the volume of the enucleated prostatic adenoma.