X-ray urethrography remains the essential procedure for assessing urethral stricture disease[1]. Simultaneous RUG and VCUG allow precise assessment to define the location, length, number, and severity of strictures. These factors will guide management decisions, especially for obliterative strictures where it is important to determine the full extent[2, 5, 8–10]. Furthermore, these key factors directly affect the choice of surgical methods and recurrence rate[2, 8, 11, 12] .
However, the single voiding method may not demonstrate certain abnormalities of the male anterior urethra because the normal anterior urethra is not fully distended[13]. To fully visualize the actual urethral caliber by filling the urethral lumen with contrast liquid, retrograde injection of contrast medium should be performed and the external meatus of the urethra should be blocked off to prevent contrast from running out[3, 4, 13].
Bach et al suggested that the operating urologist may be better off performing and interpreting the urethrogram, as this would lead to the most accurate identification of strictures and description of stricture length[14]. In this study, the urologist successfully performed urethrography procedures in all cases and obtained comprehensive key characteristics of strictures. The contrast medium was retrogradely injected through a sponge plug that occluded the urethral orifice to prevent reflux.
The amount of contrast medium is controlled during the procedures, as the approximate volume of the anterior urethra is 20–30 cc[6, 10]. This volume should serve as a guide to ensure appropriate luminal distension. Under distension of the urethral lumen can lead to underestimation of the true stricture length[8], while excessive pressure may cause the plug to slip off. Additionally, lidocaine gel was not utilized in this study to enhance the success rate[15], as it could potentially cause the plug to slip off or result in contrast medium leakage[7], and its benefit for patient comfort is questionable[10].
Several reports[6, 8, 13, 15–17] have mentioned the use of a Foley catheter, in which the balloon is gently inflated just proximal to the fossa navicularis to block the urethra. This method is attractive because it avoids contrast leakage around the genitalia and also allows the investigator to keep his or her hands well clear of the field of radiation[13]. However, Ayoob et al. have reported that proper positioning of the catheter in the urethra is crucial because placing it too far inside can obscure a distal anterior urethral stricture[8]. Ramanathan et al prefer using fluid to inflate the balloon because it is more uncompressible than air, but accidental withdrawal of the balloon can still occur during the study[6]. Excessive or overly rapid balloon distention can cause mucosal laceration, leading to intense and long-lasting pain as well as urethral bleeding. In some cases, the pain may be necessary[15–17].
Another frequently used method is the clamp system, which tightly bands the balanoprepucial sulcus with a padded ring[13, 18]. The 2–4 cm of the distal urethra (inside the glans) is not visualized in the retrograde study[3]. Ayoob et al reported that cine imaging or spot images at 2–4 frames/sec could be used to visualize the far anterior urethra as the catheter is removed and contrast empties[8]. However, this was not the actual lumen because the anterior urethra was not fully distended[13]
In this study, we observed several characteristics of the sponge plug. Firstly, it plugs the urethral meatus to prevent overflow of contrast liquid and maintain fluid pressure in the urethral lumen. Secondly, it can be easily pinched down and inserted into the meatus of the urethra, gradually expanding and adapting to its shape. This adaptation is not forceful or tough[5], but rather gentle, allowing the sponge to naturally conform to the shape of the orifice. Thirdly, the sponge absorbs contrast material, making the external urethral meatus visible in a urethrogram. Lastly, due to its soft and gentle insertion method, 72.5% of patients reported no pain with a VAS score of 0; while 27.5% experienced slight discomfort.
However, the sponge plug is still ineffective for patients suffering from urethral external meatus stricture, especially lichen sclerosis. The narrow orifice requires a slimmer adapter[5], and there is not enough space for compression and expansion of the sponge. Urologists cannot accurately observe the extent of spongiofibrosis through X-ray urethrography using sponge plugs or other conventional methods. However, sonourethrography, computed tomography urethrography, and magnetic resonance urethrography may have advantages in this regard[1, 3].