Kun Shen, Dawei Zhang, Leinan Yu
Small-volume BPO should be considered a distinct clinical phenotype in which functional mechanisms play a prominent role, although anatomical contributors may still coexist in selected patients. PUD may represent an emerging dilation-based strategy that is potentially relevant in this setting. High-quality randomized trials with long-term follow-up are required to define its durability, safety, and position in contemporary management algorithms.
BACKGROUND: Lower urinary tract symptoms (LUTS) in men have traditionally been interpreted within a volume-based paradigm, in which benign prostatic enlargement is considered the principal driver of bladder outlet obstruction. However, a subset of patients with an operationally defined small prostate volume (≤30 mL) present with disproportionate symptom severity, indicating that prostate size alone is an insufficient determinant of disease burden.
OBJECTIVES: To review the pathophysiological basis of benign prostatic obstruction in men with small prostate volume and to evaluate the emerging role of prostatic urethral dilation (PUD) within a pathophysiology-informed therapeutic framework.
EVIDENCE SYNTHESIS: Small-volume BPO is increasingly recognized as a functionally driven condition involving multiple interacting processes. Enhanced α1-adrenergic-mediated smooth muscle tone contributes to dynamic obstruction, while chronic inflammation promotes extracellular matrix remodeling and fibrotic stiffening, leading to reduced urethral compliance. In parallel, alterations in neural signaling within the bladder-prostate axis may amplify both storage and voiding symptoms. These mechanisms collectively disrupt the relationship between prostate size and symptom severity. Current treatments predominantly target either smooth muscle tone or anatomical obstruction but have limited impact on fibrosis, tissue biomechanics, or neural dysregulation. PUD represents a non-ablative, non-resective intervention that reduces urethral resistance through controlled mechanical expansion while preserving mucosal integrity. This resistance-modulating approach may be pathophysiologically relevant to small-volume BPO. Early clinical studies have reported improvements in urinary flow and symptom scores, although the evidence base remains limited.
CONCLUSION: Small-volume BPO should be considered a distinct clinical phenotype in which functional mechanisms play a prominent role, although anatomical contributors may still coexist in selected patients. PUD may represent an emerging dilation-based strategy that is potentially relevant in this setting. High-quality randomized trials with long-term follow-up are required to define its durability, safety, and position in contemporary management algorithms.