# A New Technique for Computed-Tomography Urethrography in Males: The Clamp Method
## 3 Results  
Because of the risk of gonadal irradiation, we excluded 9 patients with reproductive plans in whom the diagnosis of the urethral anomaly was evaluated by urethrography and/or urethrosonography and another 3 patients who received urethral manipulation (urethrocyystoscopy) between the urethrography/sonography and the CT. The study included 22 men with a mean age of 64 \(\pm\) 6.9 (SD) years (range, 51-77 years) and CT-RUG with the clamp method was performed successfully in all of them. The patients were distributed into 3 groups according to their urethral pathology: anterior urethral stenosis (\(n\) = 11), perinethral fistula (\(n\) = 8) and those with a urethral stent (\(n\) = 3). RSUG was only done in the 11 cases with anterior urethral structures, whereas CT-RUG and RUG were performed in all cases. VCUG was not done in 5 cases with perinethral fistulas (as RUG was enough to detect them) and VCUG revealed 3 cases with urethromeatal alterations: hypospadias (\(n\) = 1) and meatal strictures (\(n\) = 2). Of the 11 cases with anterior urethral stenosis, most were located in the bulbar urethra (\(n\) = 7) and the rest in the penile or penobulbar urethra (\(n\) = 4). All the cases had previous urethral manipulation: radical retropubic prostatectomy (\(n\) = 2), urethroplasty (\(n\) = 2), transurethral resection of the prostate (TURP) (\(n\) = 2), internal urethotomy (\(n\) = 2), urethroscopy (\(n\) = 2) and urinary catheterisation (\(n\) = 1). In the 2 cases with urethroplasty the focal strictures between the tortuous lumen of the plasty were only revealed by CT-RUG (Figure 2). In the remaining 9 cases the mean length of the stricture was 2 \(\pm\) 0.7 (SD) cm (range, 1.1-3.1 cm) on urethrography, 2.8 \(\pm\) 0.9 (SD) cm (range, 1.8-4.2 cm) on RSUG and 2.9 \(\pm\) 0.9 (SD) cm (range, 1.9-4.3 cm) on CT-RUG. An underestimation of the stricture length was found on RUG when compared to RSUG and CT-RUG (\(p\) = 0.008) (Figures 3 and 4). Figure 2: Urethral anomalies detected only by CT-retrograde urethrography: (**a**) retrograde urethrography (RUG) of patient with hypospadias and tortuous urethroplasty in the penile urethra, but no evident stenosis; (**b**) CT-RUG of the same patient showing bubble in hypospadic orifice (arrow), focal stenosis in urethroplasty and urethral lithiasis in bulbar cone (curved arrow); (**c**) 3D CT-RUG image of the same patient, showing focal stenosis in the urethroplasty (arrow) and urethral lithiasis (curved arrow), not visualized on RUG; (**d**) CT-RUG of the patient with bulbar urethral stent showing intrauterinehal bubble due to purging error (curved arrow) and discrete intra-stent spongofibrosis (arrow) not visualized on RUG. Figure 4: Patient with bulbar stenosis of a length underestimated by urethrography: (**a**) RUG showing 2.8 cm stenotic bulbar segment; (**b**) RSUG in panoramic mode (extended FOV) to visualise all of the bulbar stenosis and surrounding spongiofibrosis, measuring 4.2 cm in length; (**c**) CT-RUG showing 4.3 cm stenotic bulbar segment. (**d**): 3D CT-RUG image. Figure 3: Patient with bulbar stenosis of a length underestimated by urethrography: (**a**) RUG showing 1.7 cm stenotic bulbar segment with a drastic reduction in the caliber of the urethral lumen; (**b**) retrograde sonourethrography (RSUG) showing the stenotic bulbar segment and surrounding spongiofibrosis, measuring 3.1 cm in total; (**c**) CT-RUG showing stenotic bulbar segment measuring 3.2 cm in length (measurement similar to RSUG and greater than RUG). (**d**): 3D CT-RUG image. The eight cases with periurethral fistulas had previous surgery: radical retropubic prostatectomy (\(n=3\)), colorectal resection (\(n=3\)), TURP (\(n=1\)) and internal urethotomy (\(n=1\)). The fistula in most cases communicated the posterior urethra (\(n=3\)) or bladder (\(n=3\)) with the colorectal lumen; the case with internal post-urethotomy showed fistulous tracts towards periurethral soft tissues and a further case had a urethrovesical fistula.