Small prostate associated with higher incidence of detrusor underactivity and tendency of combination with bladder stone in patients with bladder outlet obstruction

Benign prostate hyperplasia is the leading cause of lower urinary tract symptoms due to bladder outlet obstruction (BOO) in elderly male patients. The impact of prostate volume (PV) on clinical and urodynamic characteristics was evaluated in those patients with BOO requiring prostate de-obstruction maneuvers in this study. We retrospectively reviewed the clinical data of 301 patients underwent transurethral resection of prostate due to combination with urinary retention (UR) alone and bladder stone (BS) alone. The present study investigated the differences of subjective symptoms, sonographic parameters, and urodynamic characters and assessed the proportion of UR to BS as well as the incidence of detrusor underactivity (DU) in those patients according to PV. There was not a difference of age, international prostate symptoms scores, post-voiding residual, and peak flow rate (Qmax) among 3 groups (all P > .05), whereas increasing of intravesical prostate protrusion (IPP), bladder wall thick (BWT), detrusor pressure at Qmax, bladder contractility index, bladder outlet obstruction index (BOOI), and quality of life scores with enlargement of PV was found (all P < .05). Correlations between PV and IPP (R = 0.251), Qmax (R = -0.188), post-voiding residual (R = 0.215), BWT (R = 0.170), and quality of life scores (R = 0.165) at large prostate and relationships between BWT and BOOI (R = 0.246) and bladder contractility index (R = 0.239) in moderate prostate as well as IPP and BOOI (R = 0.204) in large prostate were significantly found (all P < .05). Significant higher proportion of UR was found in patients with moderate (18%) and large prostate (47.6%) when compared to that of small prostate (3.7%), whereas higher proportion of BS was found in patients with small prostate (96.7%) compared to that of moderate (82%) and large (52.4%) prostate. Lower incidence of DU was discovered in large prostate (31.9%) compared with small (55.6%) and moderate (47.2%) prostate. BOO patients with small prostate were associated with less severity of BOO but higher incidence of DU and had a tendency of occurrence of BS, which gave a support for the theory that multifactor involved in the formation of BS rather than BOO only.