Genitourinary System

Perspective

Despite considerable advances in the initial evaluation and management of the severely injured patient, confusion remains regarding the recognition and subsequent management of genitourinary trauma. Only major renovascular injuries or a severely shattered kidney, both of which are rare, portend a rapid death. Thus most genitourinary injuries pale in comparison with the potential immediate life threats posed by concomitant injuries to the head, chest, and abdomen. The urinary tract as an anatomically injured system is by necessity relegated to a position of secondary importance. Nevertheless, to maintain clinical excellence and expertise in the overall treatment of all injured patients, the emergency physician should have a thorough understanding of the global spectrum of genitourinary injury and how it can affect patient outcomes.

Genitourinary trauma is frequently a covert entity and is associated with a wide array of injury. Approximately 10% of all multiply injured patients have some manifestation of genitourinary involvement.¹ Because of its relatively infrequent occurrence and often subtle presentation, it may be overlooked in the initial evaluation of the multiply injured patient. Prompt identification and appropriate management of genitourinary injuries can minimize potential long-term complications, including renal insufficiency, chronic hypertension, incontinence, and sexual dysfunction. The astute emergency physician can accomplish these goals by a stepwise evaluation that considers the mechanism of injury, pertinent physical examination findings, urinalysis, and adjunctive diagnostic imaging.

For the stable patient, the urinary tract is unique in that diagnostic evaluation is done in a retrograde fashion—that is, clinical suggestion and elimination of urethral injury before bladder injury before ureteral or renal injury. Adherence to this axiom enables the discovery of virtually any important urinary tract injury. Deviations from this practice may be necessary when life-threatening renal injuries are suspected.

The digital rectal examination evaluates sphincter tone, bowel wall integrity, the presence or absence of gross blood, and the position of the prostate. Normally the posterior lobe of the prostate is palpable and well defined (Fig. 47-1). A pelvic fracture may disrupt the puboprostatic ligaments and the prostatomembranous urethra, resulting in significant retropubic venous bleeding. This may produce a large pelvic hematoma that can displace the prostate superiorly, resulting in a boggy, ill-defined mass on rectal examination (Fig. 47-2). Although it has long been recommended as part of the routine evaluation of all trauma patients, multiple studies have questioned the utility of the rectal examination in this setting and have specifically demonstrated that a palpably abnormal prostate is an insensitive indicator of urethral injury.^7–10 Thus the decision to evaluate for urethral injury should consider additional clinical features, especially the presence or absence of gross hematuria or blood at the urethral meatus, and not rely on the findings of the rectal examination.

Figure 47-1 Anatomy of male genitalia.

Figure 47-2 Injury to the posterior (membranous) urethra. The prostate has been avulsed from the membranous urethra secondary to fracture of the pelvis. Extravasation occurs above the triangular ligament and is periprostatic and perivesical. (From McAninch JW: Injuries to the Genitourinary Tract. In Tanagho EA, McAninch JW [eds]: Smith’s General Urology, 14th ed. Norwalk, Conn, Appleton & Lange, 1995.)

Foley Catheter

In any significantly injured trauma patient with a major mechanism of injury and the absence of any findings suggestive of urethral injury, a Foley catheter should be passed into the bladder. The initial bladder effluent should be observed by the physician. Because of its importance in dictating subsequent patient evaluation, gross hematuria is conservatively defined as any color to the urine other than clear or yellow. The presence of gross hematuria indicates urologic injury until proven otherwise. Rarely, severe rhabdomyolysis produces large quantities of urine myoglobin, the gross appearance of which can be confused with gross hematuria. In these cases, urinalysis documents the absence of red blood cells (RBCs) consistent with myoglobinuria. Most significant lower urinary tract injuries are accompanied by a pelvic fracture, blood at the urethral meatus, or gross hematuria on spontaneous voiding or Foley catheter placement. However, injuries to the upper tract tend to be more subtle. They are often coincident with nonurologic organ disruption, the bleeding from which can be life-threatening. These events may dictate rapid volume resuscitation that can clear gross hematuria quickly. Moreover, some significant upper tract injuries, including blunt injury to the renovascular pedicle or penetrating ureteral injury, may not produce gross or even microscopic hematuria.

Lower Urinary Tract

Urethral Trauma

Anatomy

The urogenital diaphragm divides the anterior (bulbous and pendulous) urethra from the posterior (membranous and prostatic) urethra. Contrary to early descriptions, the urogenital diaphragm does not completely encircle the membranous urethra, but rather forms an incomplete sling that offers posterior and lateral support.⁵ The prostatic urethra is attached to the posterior symphysis pubis by the puboprostatic ligaments. A fracture of the pelvis with displacement of the symphysis may result in a laceration or avulsion of the prostatic urethra because of the shearing force on the fixed prostatic and membranous urethra. Injuries to the anterior and posterior urethra are caused by different mechanisms, involve different symptoms, and are treated differently.

Pathophysiology

Urethral disruption is the most significant injury to be identified. Failure to do so may lead to significant morbidity. Overly aggressive urethral manipulation can convert a partial urethral tear into a complete tear, thus precluding accurate assessment of urinary output and subsequently potentiating the long-term complications of urethral trauma (e.g., urethral stricture formation and urinary incontinence). Anterior urethral injuries are most often caused by straddle injuries, falls, gunshot wounds, and self-instrumentation (Fig. 47-3).

Figure 47-3 Injury to the bulbous urethra. Left: Mechanism: Usually a perineal blow or fall astride an object, crushing the urethra against inferior edge of pubic symphysis. Right: Extravasation of blood and urine enclosed within Colles’ fascia. (From McAninch JW: Injuries to the Genitourinary Tract. In Tanagho EA, McAninch JW [eds]: Smith’s General Urology, 14th ed. Norwalk, Conn, Appleton & Lange, 1995.)

Pelvic fractures account for most posterior urethral injuries (see Fig. 47-2). The risk of urethral injury varies with the specific type of pelvic fracture. High-risk fractures include the straddle fracture, in which all four pubic rami are involved, and the Malgaigne fracture, which involves fracture and displacement of the hemipelvis—that is, both ischiopubic rami anteriorly and the ipsilateral sacrum, sacroiliac joint, or ilium posteriorly. Urethral injuries are rarely associated with fractures that do not involve the ischiopubic rami.^5,11 In a prospective, single-center study of 203 consecutive male patients with pelvic fractures, 51 sustained urethral injuries. Malgaigne and straddle fractures were significantly associated with urethral injuries, with odds ratios of 3.4 and 3.85, respectively. In the same series, the highest risk for urethral injury was seen in patients sustaining a straddle fracture with concurrent sacroiliac diastasis (odds ratio 24). Among those sustaining fractures not involving the anterior pelvic arch, none had urinary tract injury.¹¹

Clinical Features

During the secondary survey, examination of the lower abdomen, pelvis, and genitalia provides both direct and indirect evidence to support or refute urethral injury. Urethral integrity is supported by lack of pelvic and suprapubic tenderness; absence of penile, scrotal, or perineal hematoma; and lack of blood at the urethral meatus. These physical findings permit the safe passage of a 14- or 16-Fr Foley catheter into the bladder if the patient is unable to void and provide a suitable specimen for evaluation.

Diagnostic Strategies

Catheter Placement: The following technique for catheter placement assumes a normal urethra and includes the use of sterile technique, proper control of the foreskin, the use of copious amounts of lubricating jelly, and the gentle passage of a 14- or 16-Fr Foley or coudé catheter into the bladder. In all uncircumcised patients, continuous foreskin retraction with a folded 4 × 4-inch gauze pad is necessary to control the foreskin during catheter placement (Fig. 47-4). Without this maneuver, the foreskin tends to repeatedly reduce itself over the glans penis, which contaminates the field and complicates the catheterization attempt. Slight resistance to the advancing catheter should be expected secondary to voluntary contraction of the external sphincter. This is more apt to occur in a combative, anxious trauma patient than in a cooperative or unconscious patient. When this occurs, the patient should be reassured and asked to relax the perineum and rectal area while gentle advancing pressure is applied to the catheter. This combined approach allows the catheter to navigate the external sphincter successfully and pass easily into the bladder. If reassurance and relaxation do not allow easy passage of the catheter in a male patient with clinical features suggestive of urethral injury, it should be removed and retrograde urethrography performed. The catheter is passed to its fullest extent to ensure that the balloon is completely in the bladder when inflated, The catheter is then withdrawn to the point of balloon approximation with the bladder neck, secured to the patient’s leg to prevent accidental dislodgement, and left to drain. Inflation of the catheter balloon under any other circumstances may result in iatrogenic urethral trauma.

Figure 47-4 A, A normal uncircumcised man. B, Foreskin has been retracted and a folded 4 × 4-inch gauge sponge wrapped around it to prevent foreskin reduction during instrumentation.

Successful passage of a Foley catheter precludes a complete urethral disruption. Nonetheless, the possibility of a partial urethral injury not manifested by history, mechanism of injury, or physical examination does exist. If a possible urethral injury is suggested by physical examination findings before the placement of a Foley catheter, a retrograde urethrogram should be obtained. The presence of urethral extravasation together with contrast material filling the bladder is diagnostic of a partial urethral injury (Fig. 47-5). Identification of a partial urethral injury enables one careful attempt at urethral placement of a 12- or 14-Fr Foley or coudé catheter, depending on the size of the patient.⁶ If any difficulty is encountered, the catheter should be removed and a urologist consulted. If a partial urethral tear is suggested subsequent to successful passage of a Foley catheter, a small feeding tube can be placed alongside the urethral catheter and a modified retrograde urethrogram obtained. In this circumstance the urethrogram is for documentation and subsequent management purposes only because appropriate therapy (Foley catheter drainage) has already been instituted.

Figure 47-5 Retrograde urethrogram demonstrates a partial urethral disruption. Note the elongation of the posterior urethra with filling of the bladder. (From Spirnak JP: Pelvic fracture and injury to the lower urinary tract. Surg Clin North Am 68:1057, 1988.)

Radiology: In male patients with possible urethral injury, retrograde urethrography is the diagnostic procedure of choice. Retrograde urethrography is not an emergency procedure and should follow more critical diagnostic and resuscitative measures.

In a patient with a pelvic fracture, the entire retrograde urethrogram should be obtained with the patient in the supine position. Although some authors recommend oblique films for portions of the retrograde urethrogram to enhance urethral definition, these views add little information to a good supine study. More important, pelvic fractures are often associated with significant venous bleeding and hematoma formation. Maintenance of this stable hematoma can be crucial in the initial hemodynamic resuscitation of the patient. Any patient movement from the supine to the oblique position has the potential to disrupt the organized hematoma with resultant significant and potentially lethal rebleeding. The integrity of the entire urethral length can be defined with the patient in the supine position throughout the examination, aided by oblique stretching of the penis over the left or right thigh to promote necessary urethral unfolding.

A preinjection kidney, ureter, and bladder (KUB) film is first obtained. In uncircumcised patients, the penile foreskin is retracted and secured with a folded 4 × 4-inch gauze pad (see Fig. 47-4). The penis should be held between the long and ring fingers of the nondominant hand. A simple Christmas tree adapter, a Cooke adapter placed on the end of a 60-mL Toomey syringe, or a Toomey syringe alone is gently passed into the urethral meatus until a snug fit inside the meatus is confirmed. The distal end of the syringe is secured with the thumb and index fingers of the nondominant hand (Fig. 47-6). Some authors have recommended inflation of a Foley catheter balloon just proximal to the fossa navicularis or the use of other cumbersome adjuncts to facilitate injection of contrast media. These techniques should be avoided, however, because they promote leakage of contrast material around the penis, which can simulate extravasation on the urethrogram and promote a spurious examination. Next, 60 mL (or 0.6 mL/kg in children) of full-strength or half-strength water-soluble contrast medium is injected slowly over 30 to 60 seconds. Overly forceful injection may result in intravasation of contrast material into the urethral venous plexus. A radiograph is taken during the injection of the last 10 mL of contrast material. Retrograde flow through the urethra and into the bladder without extravasation ensures continuity of the urethra and absence of urethral injury (Fig. 47-7). Extravasation of contrast material outside the urethra with concomitant evidence of bladder filling distinguishes a partial urethral injury (see Fig. 47-5) from a complete urethral disruption, in which contrast material will be absent from inside the bladder (Fig. 47-8). The latter situation requires urologic consultation for appropriate management, the timing and specifics of which remain controversial and depend on the location and mechanism of injury.^6,12,13 In the interim, if measurement of urinary output is essential, the bladder should be accessed by the suprapubic placement of a peel-away sheath and Foley catheter through use of the Seldinger technique (Fig. 47-9). When venous intravasation of contrast is suggested, a postvoid film demonstrates clearing of any intravasated material while extravasated contrast from a urethral injury remains. Retrograde urethrography should be deferred if pelvic angiography is indicated, as extravasated contrast material from a urethral injury may obscure computed tomography (CT) scans and angiographic images and complicate attempts to control significant pelvic hemorrhage by vascular embolization.¹⁴

Figure 47-6 Christmas tree adapter on the end of a 60-mL syringe has been gently placed inside the fossa navicularis in preparation for retrograde urethrography.

Figure 47-7 Normal anatomy is demonstrated by a line drawing (A) and by dynamic retrograde urethrography (B). 1, Bladder; 2, prostatic urethra; 3, verumontanum; 4, membranous urethra; 5, position of the urogenital diaphragm; 6, bulbous urethra; and 7, penile urethra. The penile and bulbous urethra together are considered the anterior urethra; the prostatic and membranous urethra constitute the posterior urethra. (Adapted from McCallum RW, Colapinto V: Urological Radiology of the Adult Male Lower Urinary Tract. Springfield, Ill, Charles C Thomas, 1976.)

Figure 47-8 Retrograde urethrograms from two patients, each demonstrating complete urethral disruption. Note the absence of bladder filling, a finding diagnostic of complete disruption. (From Spirnak JP: Pelvic fracture and injury to the lower urinary tract. Surg Clin North Am 68:1057, 1988.)

Figure 47-9 Percutaneous placement of a suprapubic tube with peel-away sheath introducer. A, An 18-gauge needle is in the bladder. A guidewire is advanced through the needle. B, A dilator and peel-away sheath are advanced over the guidewire. C, The dilator and guidewire are removed. Through the peel-away sheath, an appropriately sized catheter can be introduced into the bladder. D, The balloon is inflated, and the sheath is pulled back and peeled away. (From O’Brien WM: Percutaneous placement of suprapubic with peel away sheath introducer. J Urol 145:1015, 1991.)

Management

If the clinical features of urethral injury are absent or the urethrogram is normal, the urethra is intact and a Foley catheter can be passed into the bladder. If a partial urethral disruption is identified, one careful attempt to pass a 12- or 14-Fr Foley or coudé catheter can be undertaken. If this is unsuccessful or if a complete urethral tear is detected, placement of a suprapubic catheter for measurement of urinary outflow and volume requirements is often needed, especially if the patient is in shock or requires osmotic therapy for a severe head injury.

The optimal definitive management of urethral injuries remains a subject of controversy in the urologic literature.6,12,13 Pertinent variables include the location of the injury (anterior vs. posterior), extent of the disruption (partial vs. complete), mechanism of injury, hemodynamic stability of the patient, and presence of associated injuries. Treatment options vary from allowing a partial disruption to heal over a stenting urethral catheter to early or delayed, open or endoscopic repair. Adjunctive suprapubic urinary drainage is frequently indicated. Regardless of the specific management plan, the ultimate goals are the preservation of urinary continence and sexual function and avoidance of the disruption of any pelvic hematoma.

In female patients, proximal urethral injuries are managed by immediate surgical exploration and repair, as conservative management with proximal urinary diversion alone is associated with an increased risk of urethrovaginal fistulae or obliterative urethral strictures. Distal injuries may be managed by urethral catheterization. Regardless of the location of the urethral injury, associated vaginal lacerations require transvaginal repair to reduce the incidence of fistula formation.⁶