The correlation between clinical outcome and residual prostatic weight ratio after transurethral resection of the prostate for benign prostatic hyperplasia

Objective To assess in a prospective study the use of a new variable, the residual prostatic weight ratio (RPWR), for evaluating the clinical outcome after transurethral resection of the prostate (TURP). Patients and methods From April 1996 to lune 1997, 40 men (mean age 70.4 years, range 53-85) with symptomatic benign prostatic hyperplasia were evaluated using the American Urological Association (AUA) symptom score, measurements of the mean and maximum urinary flow rate (Q(ave) and Q(max)), and by transrectal ultrasonography (TRUS) before and 16 weeks after TURF. The estimated total prostate weight was derived as 0.52 x length x width x height x the specific gravity of the prostate (1.010). The RPWR was calculated as the prostate weight after TURF divided by the initial weight, where the value after TURF was the initial weight minus that of the TURF specimen. The clinical outcome was evaluated by the difference (Delta) in AUA score, Q(ave) and Q(max) before and 16 weeks after surgery. Results There was a close correlation between the estimated prostate weight and the actual weight of the TURF specimen (r = 0.82 and 0.80 for the adenoma and total prostate, respectively). The mean (SD) RPWR, Delta AUA score, Delta Q(max) and Delta Q(ave) were 50.1 (17.1)%, 11.5 (5.3), 9.9 (4.2) mL/s and 6.2 (2.9) mL/s, respectively. There was a negative correlation between the RPWR and the Delta AUA, Delta Q(max) and Delta Q(ave) (r = -0.81, -0.68, and -0.70, respectively, P < 0.05). The prostate volume estimated by TRUS decreased significantly 16 weeks after TURF. Conclusions TRUS is a useful tool for estimating prostate weight before surgery. The smaller the RPWR at 16 weeks after TURF, the better the clinical outcome.