How does Benign Prostatic Hyperplasia (BPH) cause urinary difficulties?
The Prostate can lead to the constipation of the urethra and bladder by 2 mechanisms. One by the urethral lumen stenosis for the increase of the prostatic volume (static component).
The other one is the dynamic component that consists of the smooth muscle tone, mediated by the noradrenaline effect in the adrenergic receptors found on the prostate stroma, on the prostate capsule, and the urethra.
Increasing this tone can hurry the sudden reduction of the urinary flow or even acute urinary retention, needing a catheterization. The tone can be decreased with adrenergic agonists (α-blockers), being the basis of one of the main forms of current medical therapy.
The fact that adrenergic receptors exist in other body areas explains the wide range of adverse effects frequently visible with this medication. This way, urinary complaints associated with benign prostatic hyperplasia (BPH) have two origins: anatomic and neurohormonal.
A large part of the symptoms is related to the muscular tone increase and the muscular pressure on the urethra, prostate stroma, and bladder neck through α-adrenergic receptors.
The volumetric increase with consequent anatomic compression of the urethra, which stays long and with an exaggerated posterior shape, is another essential factor. Other factors are neurotransmitters and neuroendocrine cells in the prostate tissue.
As a whole, benign prostatic hyperplasia (BPH) leads to trabeculation and hyperplasia of the detrusor muscle by chronic constipation (“urinary incontinence”), which can be accompanied by venous dilation.