Urethra stenosis

Macroscopically Non-stimulative Surfaces. When a biomaterial moves relative to the contacting tissue, the tissue surface is often damaged by mechanical abrasion resulting, for instance, in stenosis for the case of tubular tissues such as the urethra (1). Most of the inner and outer surfaces of soft tissues are lubricious because the surface is covered with a mucous layer though skin is one exception. Due to this lubricity serious damage to the tissue surfaces can be avoided even if they are brought in frictional contact with each other. In contrast to natural tissues, artificial materials generally do not possess such lubricious surfaces. A method to render the artificial surface lubricious is to coat it with a hydrophilic layer. 

Obstruction of the lower urinary apparatus can be caused by primitive lesions of the urethra or lesions secondary to compression by an enlarged prostate or perineal masses. The most frequent cause of non-prostatic obstructive dysuria is acquired stenosis, which can be divided into post-inflammatory, post-traumatic and post-surgical. 

Fig. 19.5. Post-surgical stenosis after prostatectomy. Voiding sonography shows a stenosis (arrowheads) at the distal end of the prostatic urethra...

Fig. 19.7. Distal urethral stenosis studied with sonourethrography. Long stenosis of the bulbo-perineal urethra. The mucosa is hyperechoic with strong spots due to fibrotic strictures. The corpus spongiosum is thinned and hyperechoic due to chronic inflammation...

Because of its length, the male urethra is vulnerable to traumatic lesions that may cause acute urinary retention and sudden onset of urethrorrhagia and even late stenosis. Urethral trauma can be divided into external trauma, either contusive or penetrative, and internal or endourethral trauma. Internal traumas usually follow iatrogenic maneuvers. External traumas are frequent events and can occur in the penile urethra as a result of road or work accidents, sporting activities or sex. The urethra can be compressed by subcutaneous or intraspongiosal hematomas and may present complete or incomplete mucosal interruption. 

Fig. 19.12. Infiltrating transitional cell carcinoma of the bulbous urethra. Sonourethrography in sagittal scan. The sonogram shows the lesion protruding in the urethral lumen (arrowheads) with secondary stenosis. The surrounding spongiosa is involved (curved arrows)...

Hoebeke PB, Van Laecke E, Raes A et al (1997) Membrano-bulbo-urethral junction stenosis. Posterior urethra obstruction due to extreme caliber disproportion in the male urethra. Eur Urol 32 480-484 Kawashima A, Sandler CM, Wasserman NF et al (2004) Imaging of urethral disease a pictorial review. Radiographics 24 [Suppl 1] S195-216... 

Fig. 21.11. Sagittal scan obtained after SonoVue microbubble administration showing a stenosis of the bulbar urethra (arrowhead)...

Fig. 6.11. VCU in a 7-year-old boy with history of dys-uria no history of trauma. During micturition, a distended posterior urethra was identified as well as a diverticulum associated with stenosis...

Hypospadia is a frequent anomaly of the urinary meatus that can be associated with significant stenosis and dilatation of the male urethra. Though possible in most cases, catheterization of the urethra can be difficult and painful. 

Fig.6.13a,b. US and VCU in a 7-year-old boy with gross hematuria and painful dysuria. a Irregular thickening of the base of the bladder on US. b Elevation of the bladder, irregular stenosis of the bladder neck, and proximal posterior urethra. Prostatic rhabdomyosarcoma was suspected. Cystoscopy and biopsies were negative. Urinary culture was positive. Final diagnosis was E. coli pseudotumoral cystitis... 

Distal hypospadias is more likely to have a urethra of normal diameter with no meatal stenosis and... 

The key questions to address by imaging are as follows is there any urethral leak (the absence of a leak cannot exclude hematoma or contusion) and is there any retrograde opadfication of the bladder (allowing the differential diagnosis between complete and partial disruption of the urethra) The followup of patients is of primary importance. The aim is to detect urethral stenosis or diverticulum. Again, prudent retrograde opacification is the optimal examination. 

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