Functional Evaluation of Upper Urinary Tract with Diuretic Mercaptoacetyltriglycine Renal Scans in Patients with Benign Prostatic Obstruction before and after Surgical Intervention: A Pilot Study

INTRODUCTION: We investigated which benign prostatic hyperplasia-related lower urinary parameters are related to upper urinary tract obstruction and whether transurethral prostatectomy could improve upper urinary tract obstruction. MATERIALS AND METHODS: Patients with prostate size over 30 g and urodynamically proven bladder outlet obstruction were enrolled in this prospective observational study. Bladder wall thickness and prostate size were measured by ultrasonography. A urodynamic study with laboratory tests including serum creatinine, prostate-specific antigen, and urinalysis was performed. Finally, a diuretic scintigraphy using mercaptoacetyltriglycine was performed. Tests except the urodynamic evaluation were repeated after transurethral prostatectomy. RESULTS: In total, 24 patients were enrolled, and 19 patients completed the present study. The mean values of age (yrs), prostate size (mL), bladder thickness (mm), bladder compliance (ΔmL/Δpr), and the bladder outlet obstruction index were 68.42 ± 8.25, 72.29 ± 32.78, 4.42 ± 1.14, 50.17 ± 32.15, and 82.11 ± 34.68, respectively. The mean T(1/2) (min) was 17.51 ± 16.34 on the left side and 15.30 ± 11.96 on the right side. Statistical analysis showed that bladder compliance and bladder thickness were preoperatively related to upper urinary tract obstruction (p = 0.001 and p = 0.007, respectively). Diuretic mercaptoacetyltriglycine scan in 19 patients showed improvement 6 months after prostate surgery. Clinically significant proteinuria was associated with upper urinary tract obstruction, and proteinuria was also improved after prostate surgery. CONCLUSION: Storage-phase bladder dysfunction could be a reliable urodynamic factor for the indication of upper urinary tract obstruction in patients with benign prostatic hyperplasia, and upper urinary tract obstruction with subsequent kidney damage could be improved by surgical decompression of benign prostatic obstruction.