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 June 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 (Qave and Qmax), and by transrectal ultrasonography (TRUS) before and 16 weeks after TURP. 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 TURP divided by the initial weight, where the value after TURP was the initial weight minus that of the TURP specimen. The clinical outcome was evaluated by the difference (Delta) in AUA score, Qmax and Qave before and 16 weeks after surgery.
Results: There was a close correlation between the estimated prostate weight and the actual weight of the TURP specimen (r = 0.82 and 0.80 for the adenoma and total prostate, respectively). The mean (SD) RPWR, DeltaAUA score, DeltaQmax and DeltaQave were 50.1 (17.1)%, 11.5 (5. 3), 9.0 (4.2) mL/s and 6.2 (2.9) mL/s, respectively. There was a negative correlation between the RPWR and the DeltaAUA, DeltaQmax and DeltaQave (r = -0.81, -0.68, and -0.70, respectively, P < 0.05). The prostate volume estimated by TRUS decreased significantly 16 weeks after TURP.
Conclusions: TRUS is a useful tool for estimating prostate weight before surgery. The smaller the RPWR at 16 weeks after TURP, the better the clinical outcome.