PASTIS-Trial: Pre-operative Assessment by Sonourethrography Only in Anterior Urethral Strictures: A Prospective Feasibility Trial

Urethral stricture disease (USD) is a medical condition in which a narrowing of the urethral lumen occurs due to pathological fibrosis and cicatrix formation of the urethral mucosa and surrounding spongious tissue (spongiofibrosis). Urethral strictures may occur at any location from the bladder neck to the external urethral meatus and are categorized based on their localisation in anterior strictures (including the urethral meatus, penile urethra and bulbar urethra) and posterior strictures (including the prostatic urethra and membranous urethra). USD is a disease of all ages but the prevalence increases with increasing age since the cumulative risk of having had urethral instrumentation equally increases. All processes that cause urethral trauma may provoke USD. The majority of strictures nowadays is idiopathic or caused by iatrogenic trauma of the urethra.

The pathological narrowing of the urethral lumen can lead to a wide variety of symptoms which ask for specific diagnostic investigations, in which imaging of the urethra plays a central role. Retrograde urethrography (RUG) and voiding cystourethrography (VCUG) are considered to be the gold standard diagnostic investigation techniques for diagnosis of USD.

In both techniques, contrast is instilled in the urethra through the urethral meatus and radiographic imaging is used to visualize the urethra. RUG and VCUG offer the possibility to visualize the urethra completely and to evaluate the number, length and location of urethral strictures. On the other hand, these techniques have some crucial disadvantages. First and foremost, the radiation load of the genitopelvic region in often young patients is inevitable in RUG and VCUG. Secondly, it is impossible to evaluate the degree of spongiofibrosis with radiographic imaging.

In 1988, McAnnich, et al. were the first to describe sonourethrography (SUG) for the diagnosis of anterior urethral strictures in males. In this technique, a Foley catheter is inserted in the urethral meatus and a physiological solution is instilled in the urethra while a linear 7,5 MHz ultrasound probe is placed sagitally over the course of the urethra. SUG is not only able to evaluate the length and localization of a US, but it also enables the investigator to evaluate the grade of spongiofibrosis.

Different strudies have shown that SUG has a higher sensitivity for the measurement of urethral stricture length compared to classical radiographic imaging such as RUG or VCUG. Since the choice of the most adequate surgical technique depends on the length of the urethral stricture, correct estimation of the urethral stricture length is of the utmost importance.