THE URODYNAMIC IMPACT OF TRANSRECTAL HIGH-INTENSITY FOCUSED ULTRASOUND ON BLADDER OUTFLOW OBSTRUCTION

Objectives: The aim of this study was to determine the urodynamic impa ct of transrectal high-intensity focused ultrasound (HIFU), which is p resently evaluated as a minimally invasive treatment option for benign prostatic hyperplasia (BPH), on bladder outflow obstruction by means of pressure flow analyses. Methods: A total number of 30 patients suff ering from symptomatic BPH underwent pressure flow studies before and after transrectal HIFU (mean time interval. 4.5 months; range: 3-6 mon ths). In parallel, the international prostate symptom score (IPSS), fr ee flow and postvoid residual volume were determined at regular time i ntervals postoperatively. Results: The IPSS decreased from preoperativ ely 15.8 +/- 5.9 (n = 30; mean +/- SD) to 6.9 +/- 4.4 at 3 months (n = 30) and 7.2 +/- 5 at 6 months (n = 30). Within the same time period t he maximum uroflow (Q(max); ml/s) increased from 8.8 +/- 2.2 to 11.3 /- 3.4 (3 months) and 12.1 +/- 3.6 (6 months) and the postvoid residua l volume (ml) declined from 100 +/- 47 to 44 +/- 33 and 55 +/- 50, res pectively. Pressure flow studies revealed a reduction of the minimal v oiding pressure (cm H2O) from preoperatively 70 +/- 23 (mean +/- SD) t o 51 +/- 22 (p < 0.005) postoperatively and a decline of the detrusor pressure at maximum flow (cm H2O) from 74.2 +/- 24 to 57 +/- 15 (p < 0 .005). The linear passive urethral resistance relation (linear PURR) d ropped from 3.7 +/- 1.1 to 2.2 +/- 1.2 (p < 0.005). According to the A brams-Griffiths nomogram, 24 (80%) patients were classified preoperati vely as obstructed, the remaining 20% as being in equivocal zone. Post operatively, 13% were unobstructed, 50% in the equivocal zone and 37% of patients were rated as obstructed. Conclusion: Transrectal HIFU is capable of improving objective and subjective BPH parameters as well a s of decreasing the degree of bladder outflow obstruction.