Male urethral strictures - Causes and pathogenesis

Causes of urethral stricture in men

Strictures of the urethra in men can be caused by sexual trauma, which occurs when the cavernous bodies of the penis are torn (fractured), and also when masturbating with various foreign bodies.

Inflammatory strictures associated with gonorrhea are now less common than they used to be, due to the availability of effective antibacterial treatment. These strictures most often affect the bulbous and, less often, the penile parts of the urethra, and the strictures are often long, sometimes extending to the entire spongy part.

The importance of chlamydia and ureaplasma (non-specific urethritis) in the development of inflammatory narrowing of the urethra remains unclear.

Xerotic obliterating balanitis (lichen sclerosus) is classified as a non-venereal infection, but its etiological factor remains unclear.

The scleroatrophic process initially affects either the skin of the glans penis or the inner layer of the foreskin and only then moves to the external opening of the urethra (meatus) and the scaphoid fossa, causing the development of meatostenosis. The lesion can also spread to a significant part of the spongy part of the urethra, causing the development of an extensive and severe stricture. Although the use of antibiotics in these patients is advisable to limit obstructive symptoms of urination, the literature data do not confirm the limiting role of antibiotic therapy in the progression of urethral strictures.
A urethral catheter can also be the cause of inflammatory stricture, contributing to the development of acute and chronic urethral infections, and therefore urethral strictures. Invasive nosocomial infection plays a special role here.

Congenital strictures of the urethra occur in the form of meatostenosis in hypospadias, as well as at the border of the bulbous and membranous urethra, where two embryonic rudiments merge. They are detected in early childhood, the diagnosis is established by excluding traumatic and infectious factors.

Idiopathic strictures, i.e. strictures of unclear etiology, are more common in the bulbous region. According to statistics, their frequency reaches 11-15% when an adult man has no history of trauma, urethritis, catheterization, etc.

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Pathogenesis of urethral stricture in men

Injuries to the membranous urethra in pelvic bone fractures

Pelvic bone fractures, ruptures of the muscles of the urogenital and pelvic diaphragms usually cause a complete rupture of the urethra, i.e. a rupture through all layers along the entire circumference with a divergence of the ends of the urethra by a smaller (0.5 cm) or greater (1-3 cm) distance. The hematoma in the area of injury to the urethra is absorbed and replaced by fibrosis. The scar area always has clear boundaries with normal tissues. The more severe the injury, the longer it will take for the hematomas to be resorbed and collagen scar fields to form. Therefore, the terms of restorative surgery after mild and moderate pelvic bone injuries with their favorable rehabilitation and uncomplicated course of injury to the urethra, timely and complete bladder diversion of urine can be 2.5-3 months. Severe bone injuries and/or complications from the urinary system (pelvic urinary infection, pelvic or paraurethral abscesses with opening) shift the recovery period of the urethra to 4-6 months after the injury.

Injuries to the bulbous urethra due to blunt trauma to the perineum

The injury may affect only the spongy body without damaging the mucosa or be penetrating, i.e. with a rupture of the mucosa. The injury may be with a complete interruption of the urethra (the divergence of the ends is usually insignificant: 0.5-1 cm) or partial, when part of the urinary tract remains. In any case, a periurethral hematoma is formed either in the form of tissue impregnation with blood or in the form of a blood cavity. Resorption of hematomas will occur mainly within 2, maximum 3 weeks. By 6-8 weeks, a dense scar of the urethra and periurethral tissues will be formed. Restoration of the urethra is possible and advisable 6-8 weeks after the injury. In the presence of infection in the area of the injury and drainage of the inflammatory focus, the period of restoration of the urethra is shifted to the end of the 3rd month after the injury.

The distinctive features of inflammatory strictures of the spongy part of the urethra are:

1. as a rule, a hidden beginning of development;
2. slow gradual progression over months and years
3. lack of clear boundaries of the lesion of spongy tissue;
4. progression of inflammation and spongiofibrosis after surgical treatment of inflammatory strictures of the urethra;
5. periurethral fibrosis with damage to the muscles and tissue of the perineum;
6. inflammatory lesion of the skin of the perineum, scrotum, penis in some cases.

The role of urinary infiltration in the development of inflammatory strictures is exaggerated. Of course, after desquamation of the epithelium, the subepithelial connective tissue comes into contact with urine during urination, but it is not the urine itself that is harmful, but the bacterial factor, which is capable of causing tissue destruction with subsequent fibrosis even without urine. It is the structural feature of the spongy body (the "bundle" of venous trunks) that contributes to the progression of inflammation throughout the body and the absence of clear boundaries of the lesion.