Increased detrusor collagen is associated with detrusor overactivity and decreased bladder compliance in men with benign prostatic obstruction

Background This study aimed to investigate the relationship between detrusor collagen content and urodynamic parameters in men with benign prostatic obstruction. Material and methods Nineteen consecutive patients undergoing open prostatectomy for bladder outlet obstruction (BOO) due to benign prostatic hyperplasia (BPH) were evaluated. Urodynamic tests were performed in all patients. BOO and detrusor contractility were assessed with the BOO index (BOOI) and the bladder contractility index (BCI), respectively. A bladder fragment was obtained during prostatectomy. Eight cadaveric organ donors composed the control group. Bladder sections were stained with picrosirius red and hematoxylin-eosin. The collagen to smooth muscle ratio (C/M) in the detrusor was measured and its relationship with urodynamic parameters was investigated. Results Seven (36.8%) patients were operated on due to lower urinary tract symptoms and 12 (63.2%) had urinary retention. The mean prostate volume was 128.6 cm 3 ± 32.3 cm 3 , the mean BOOI was 76.4 ± 33.0, and the mean BCI was 116.1 ± 33.7. The mean C/M in BPH patients and controls were 0.43 ± 0.13 and 0.33 ± 0.09, respectively ( P = 0.042). A negative correlation was shown between C/M and bladder compliance ( r = –0.488, P = 0.043). The C/M was increased in BPH patients with detrusor overactivity (DO) compared to those without DO (0.490 ± 0.110 and 0.360 ± 0.130, respectively; P = 0.030) and also in patients with urinary retention ( P = 0.002). No correlation was shown between C/M and maximum cystometric capacity, BOOI, or BCI. Conclusion Men with BOO/BPH have increased detrusor collagen content which is associated with decreased bladder compliance, detrusor overactivity, and urinary retention.