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While injuries to the urethra are relatively rare compared to other segments of the genitourinary tract, urethral injury can be seen in 4-24% of male patients with pelvic fractures.1-4 Although rarely life-threatening, urethral injuries can lead to significant long-term morbidity. 1,2 Retrograde urethrography (RUG) continues to be the best initial diagnostic study for evaluating acute male urethral trauma and post-traumatic complications. 5,6 Accurate technique in performing these procedures in both the pre- and postoperative settings can be challenging, and knowledge of normal and abnormal findings is essential to guiding management and treatment. This review article will highlight normal urethral anatomy, describe the appropriate techniques for conducting RUG examinations, accompanied by practical troubleshooting strategies; and review post-traumatic pathologies.
Normal Anatomy
The male urethra extends from the external meatus to the urinary bladder with a length ranging from 17 to 24 cm (reported mean 22 ± 2.4 cm).7 The urethra is divided into anterior and posterior segments separated by the urogenital diaphragm (Figure 1). The anterior urethra extends from the external meatus to the urogenital diaphragm and is subdivided into a proximal bulbous segment and a distal penile segment, spanning approximately 16 cm. The distal-most aspect of the anterior urethra is termed the fossa navicularis; it is approximately 1 to 1.5 cm in length. The Cowper's glands, located within the urogenital diaphragm, drain into the proximal bulbous segment. The periurethral Littré glands are located in the dorsal aspect of the penile urethra and distal bulbous urethra.
The posterior urethra extends from the urogenital diaphragm to the urinary bladder, measuring approximately 5 cm. It is subdivided into a proximal prostatic segment and a distal membranous segment. The verumontanum is a 1 cm-long ovoid mound located in the posterior wall of the prostatic urethra, the center of which contains the prostatic utricle. The prostatic utricle is flanked bilaterally by the ejaculatory ducts. The internal urethral sphincter spans the length of the bladder neck to just proximal to the verumontanum. The intrinsic urethral sphincter is located distal to the verumontanum within the distal prostatic urethra. The extrinsic sphincter arises from the levator ani complex and surrounds the membranous urethra.
Indications
Indications for RUG include trauma, lower urinary tract structural abnormalities, urethral masses, and postoperative evaluation (Table 1). The most common...