Urethral Trauma

Introduction

Trauma to the male urethra must be efficiently diagnosed and effectively treated to prevent serious long-term sequelae. Patients with urethral stricture disease from poorly managed traumatic events are likely to have significant voiding problems and recurring need for further interventions. Many of these men have significant orthopedic and neurologic injuries as well. Rehabilitation requires reconstruction of the urinary tract in a manner that does not interfere with the healing process.

History of the Procedure

Most urethral injuries are associated with well-defined events, including major blunt trauma such as caused by motor vehicle accidents or falls. Penetrating injuries in the area of the urethra may also cause urethral trauma. Straddle injuries may cause both short- and long-term problems. Iatrogenic injury to the urethra from traumatic catheter placement, transurethral procedures, or dilation is not uncommon.

Problem

Urethral injuries can be classified into 2 broad categories based on the anatomical site of the trauma. Posterior urethral injuries are located in the membranous and prostatic urethra. These injuries are most commonly related to major blunt trauma such as motor vehicle accidents and major falls. They are most commonly associated with pelvic fractures. Injuries to the anterior urethra are located distal to the membranous urethra. Most anterior urethral injuries come from blunt trauma to the perineum (straddle injuries), and many have delayed manifestation, appearing years later as a stricture.

External penetrating trauma to the urethra is rare, but iatrogenic injuries are quite common in both segments of the urethra. Most are related to difficult urethral catheterizations.

Frequency

Posterior urethral injuries are most commonly associated with pelvic fracture, with an incidence of 5-10%. With an annual rate of 20 pelvic fractures per 100,000 population, these injuries are not unusual occurrences. Anterior urethral injuries are less commonly diagnosed emergently, thus the actual incidence is difficult to determine. However, many men with bulbar urethral strictures recall an antecedent perineal blunt injury or straddle injury, making the true frequency of anterior injury much higher. Penetrating injury to the urethra is rare, with major trauma centers only reporting a few per year.

Etiology

As with many traumatic events, the etiology of a urethral injury can be classified as blunt or penetrating. In the posterior urethra, blunt injuries are almost always related to massive deceleration events such as falls from some distance or vehicular accidents. These patients most often have a pelvic fracture involving the anterior pelvis. Blunt injury to the anterior urethra most often occurs from a blow to the bulbar segment such as occurs when straddling an object or from direct strikes or kicks to the perineum. Blunt anterior urethral trauma is sometimes observed in the penile urethra in the setting of penile fracture.

Penetrating trauma most often occurs to the penile urethra. Etiologies include gunshot and stab wounds. Iatrogenic injuries to the urethra occur when difficult urethral catheterization leads to mucosal injury with subsequent scarring and stricture formation. Transurethral procedures such as prostate and tumor resections and ureteroscopy can also lead to urethral injury.

Pathophysiology

Injury to the posterior urethra occurs when a shearing force is applied at the prostatomembranous junction in blunt pelvic trauma. The prostatic urethra is fixed in position because of the attachments of the puboprostatic ligaments. Displacement of the bony pelvis from a fracture type injury thus leads to either tearing or stretching of the membranous urethra.

Anterior urethral injury most often results from a blunt force blow to the perineum, producing a crushing effect on the tissues of the urethra. The initial injuries are often ignored by the patient, and urethral injury manifests years later as a stricture. The stricture results from scarring induced by ischemia at the site of the injury. Penetrating injuries also occur in the anterior urethra as a result of external violence.

Presentation

Diagnosis of urethral injuries requires a reasonably high index of suspicion. Urethral injury should be suspected in the setting of pelvic fracture, traumatic catheterization, straddle injuries, or any penetrating injury near the urethra. Symptoms include hematuria or inability to void. Physical examination may reveal blood at the meatus or a high-riding prostate gland upon rectal examination. Extravasation of blood along the fascial planes of the perineum is another indication of injury to the urethra. "Pie in the sky" findings revealed by cystogram usually indicate urethral disruption.

The diagnosis is made by performance of a retrograde urethrogram, which must be performed prior to insertion of a urethral catheter to avoid further injury to the urethra. Extravasation of contrast demonstrates the location of the tear. Further management is predicated on the findings of urethrography in combination with the patient's overall condition.

Relevant Anatomy

The male urethra may be divided into 2 portions. The posterior urethra includes the prostatic urethra, which extends from the bladder neck through the prostate gland. It then joins the membranous urethra, which lies between the prostatic apex and the perineal membrane. The anterior urethra begins at that point and includes 3 segments. The bulbar urethra courses through the proximal corpus spongiosum and ischial cavernosus-bulbospongiosus muscles to reach the penile urethra. The penile urethra then extends through the pendulous portion of the penis to the final segment, the fossa navicularis. The fossa navicularis is invested by the spongy tissue of the glans penis.

Potential areas for injury can be deduced from further study of the urethral anatomy. The membranous urethra is prone to injury from pelvic fracture because the puboprostatic ligaments fix the apex of the prostate gland to the bony pelvis and thus cause shearing of the urethra when the pelvis is displaced. The bulbar urethra is susceptible to blunt force injuries because of its path along the perineum. Straddle-type injuries from falls or kicks to the perineal area can result in bulbar trauma. Conversely, the penile urethra is less likely to be injured from external violence because of its mobility, but iatrogenic injury from catheterization or manipulation can occur, which is also possible in the fossa navicularis.

Contraindications

In cases of urethral trauma, patients often have multiple injuries. Immediate urethral repair is contraindicated because life-threatening injuries must be corrected first in any trauma algorithm. Urethral repair must be delayed until the pelvic hematoma has stabilized and hemorrhage is less of a concern.

Penetrating anterior urethral injuries should be explored; however, defects longer than 2 cm in the bulbar urethra and longer than 1.5 cm in the penile urethra should never be emergently repaired. They should be reconstructed at an interval following the injury to allow for resolution of other injuries and proper planning of the tissue transfers required for the repair.