Does prostate size predict the urodynamic characteristics and clinical outcomes in benign prostate hyperplasia?

Bladder outlet obstruction (BOO) in large and small prostates is managed in a similar manner despite considerably different pathophysiology, which can result in higher failure rates. We investigate the clinical and urodynamic features and study the outcome of patients with benign prostate hyperplasia (BPH) according to their prostate size.

We prospectively analyzed 100 BPH patients undergoing urodynamic study between January 2015 and August 2016 and divided them into two groups according to their prostate size: small (≤30 mL) and large prostate (>30 mL) groups. We compared the groups regarding age, International Prostate Symptom Score, maximal flow rate (Qmax), postvoided residual, serum prostate-specific antigen (PSA), prostate volume measured by ultrasonography (USG), and urodynamic findings.

For testing the hypothesis, we used the Chi-square test, Student's t-test, and one-way analysis of variance when comparing between groups and conducted the logistic regression analysis for determining predictive factors of BOO.

Although the total prostate volume significantly correlated with the PSA, patients with a small prostate had lower Qmax (5.27 ± 4.8 mL/s vs. 6.14 ± 6.66 mL/s; P = 0.74), higher incidence of abnormal baldder capacity (39.9% vs. 31.25%), lower voiding efficiency (39.3 ± 40.5% vs. 40.57 ± 32.11%), low compliance (44.4% vs. 31.3%), higher incidence of indeterminate detrusor contractions (38.9% vs. 37.5%), lower incidence of detrusor underactivity (33.3% vs. 28.1%), lower BOO index (40.9 ± 43.2 vs. 49.10 ± 44.48), lower bladder contractility index (77.8 ± 48.84 vs. 92.09 ± 52.79), and lower PdetQmax (51.44 ± 42.23 vs. 61.38 ± 42.01 cmH₂O). Small prostates had higher failed voiding trials postsurgery.

BOO patients with a small prostate showed poor urodynamic parameters and reported higher postoperative complications.