1.13 Urological injuries in pelvic ring trauma: assessment and management in male patients

10.1055/b-0035-121637

1.13 Urological injuries in pelvic ring trauma: assessment and management in male patients

Ron Kodama, Raj Satkunasivam

1 Anatomy and classification

The bladder sits in a well-protected anatomical position due to its deep location in the bony pelvis. Blunt injuries can occur through a variety of mechanisms, with motor vehicle collisions being the predominant cause. In this situation the bony pelvis is disrupted, which may tear the bladder at its fascial attachments, or bone fragments may lacerate the bladder. It is rare to observe bladder injuries from blunt trauma in isolation, and the mortality in these multiple-injured patients will likely be due to nonurological injuries [1, 2]. Pelvic fractures are highly associated with bladder injuries, occurring in up to 95% of patients with bladder injuries while 5–10% of pelvic fractures have a concomitant bladder injury [3].

Bladder trauma can be classified into extraperitoneal and intraperitoneal injuries. Extraperitoneal injuries are commonly associated with pelvic fractures, whereas intraperitoneal injuries can occur in isolation, often from blunt trauma to a full bladder with resultant rupture at the bladder dome.

The adult male urethra can be divided into anterior and posterior components that are further subdivided based on anatomical location and surrounding structures ( Fig 1.13-1 ). The anterior urethra includes the bulbous and penile urethra. The most distal portion of the penile urethra is the specialized portion of the glandular urethra called the fossa navicularis. The relationship of the urethra to the bony and fascial attachment within the pelvis as well as the dual urinary sphincter mechanisms must be appreciated to understand the mechanism of urethral injuries associated with pelvic fractures, their management, and potential complications. These urethral injuries are most commonly associated with multisystem trauma, often in the context of motor vehicle collisions. The term posterior urethral injury is a misnomer and should no longer be used. The recommended term is pelvic fracture urethral injury (PFUI), since most PFUI injuries occur at the bulbomembranous junction. Previously, the term pelvic fracture-urethral distraction defect had been used to describe these injuries. Recently, the mechanism of injury has been hypothesized not to be only a distraction or disruption type of injury but could also be caused by other mechanisms depending on the type of pelvic fracture and degree or type of ligamentous injury [4].

Fractures involving the anterior pelvic ring, particularly displaced fractures of the inferomedial pubic bone and symphysis pubis diastasis are highly associated with the presence and extent of urethral injury [5]. Fractures involving all four pubic rami as well as those with resultant vertical and rotational pelvic instability carry the highest risk of urethral injury [6]. Stable pelvic fractures (Tile classification type A) are rarely associated with PFUI [4]. Aihara et al [7] have described that a widened pubic symphysis (relative risk [RR] = 2.9; P = .003), sacroiliac joint involvement (RR = 1.8; P = .04) or fracture of the inferior ramus (RR = 4.6; P = .008) were particularly associated with urethral injury. In this same study, a widened symphysis and fracture of the inferior pubic ramus were independently associated with urethral injuries on multivariate analysis. In another study [8], straddle fractures involving bilateral superior and inferior rami and Malgaigne fractures (completely unstable) were highly associated with PFUI with odds ratios of 3.85 and 3.40, respectively. The bulbomembranous junction, as opposed to the prostatomembranous junction, is most susceptible to injury when there is pelvic fracture. This is because the posterior urethra is adherent to the pubis through attachment to the urogenital diaphragm and puboprostatic ligaments. Andrich et al [4] have proposed mechanisms by which urethral injuries occur, taking into consideration the transmission of force vectors through the pubopropstatic ligaments and urogenital diaphragm based on the Tile classification of fractures ( Table 1.13-1 ). Importantly, in contrast, injuries in children may extend up to the bladder neck, owing to an undeveloped prostate.

**Table 1.13-1** Mechanisms of posterior urethral injuries according to Tile’s classification. Consequences of pelvic ring fractures are mediated through the attachments of the perineal membrane and the puboprostatic ligaments to the urethra and the way these ligamentous structures respond to pelvic ring disruption (image adapted from [4], with permission).

Several classification systems for PFUI have been proposed in the literature to facilitate management and outcome evaluation; however, none has gained widespread application. These include classifications by Colapinto, Goldman, Al-Rifeai, the American Association for Surgery of Trauma (AAST), and most recently, the European Association of Urology [9–13]. Each classification has its inherent strengths and limitations. The main limitation of these grading systems is that none are reliably utilized to report of long-term reconstructive surgery outcomes. The recent International Consultation of Urologic Disease has recommended the use of the AAST classification ( Table 1.13-2 ) [13].

**Table 1.13-2** American Association for the Surgery of Trauma organ injury scaling III classification of urethral injuries [13].
Type	description appearance
I	Contusion blood at the urethral meatus; normal urethrogram
II	Stretch injury elongation of the urethra without extravasation on urethrography
III	Partial disruption extravasation of contrast at injury site with contrast visualized in the bladder
IV	Complete disruption extravasation of contrast at injury site without visualization in the bladder; < 2 cm of urethral separation
V	Complete disruption complete transection with > 2 cm urethral separation, or extension into the prostate or vagina

2 Bladder injuries

2.1 Acute evaluation

Depending on the consciousness of the patient, the clinician must consider the mechanism of injury (eg, seat belt), associated injuries (a pelvic fracture), and signs and symptoms to suspect a bladder injury. A patient may complain of nonspecific symptoms, such a suprapubic pain or discomfort together with an inability to void. Physical signs range from suprapubic tenderness or guarding to an enlarged scrotum with ecchymosis. Other abdominal pelvic injuries may mask bladder injuries, particularly in patients with an altered sensorium from neurological injury or intoxication. A Focused Abdominal Sonography for Trauma examination may identify free intraperitoneal fluid.

If a bladder injury is suspected, a urethral catheter should be inserted. One should suspect a synchronous urethral injury, if there is blood at the urethral meatus or if resistance is encountered when passing the urethral catheter. The presence of gross hematuria is highly sensitive for the presence of a bladder injury [14] and if present, imaging must be done to rule out bladder injury. Also, in trauma patient with gross hematuria, a contrast computed tomographic (CT) scan with delayed imaging should be performed to rule out an upper tract injury (kidney and ureter). An unrecognized bladder injury may present in a delayed fashion with low urine output, azotemia, peritonitis, ileus, and intraabdominal sepsis.

Diagnostic imaging to confirm a suspected bladder injury is absolutely indicated in all patients with pelvic fracture and gross hematuria. In the population of patients having gross hematuria and a pelvic fracture, approximately 29% have a bladder injury [15]. A plain film cystogram with retrograde filling of contrast (at least 350 mL) together with drainage films or a CT cystogram with retrograde filling are equally reliable methods to identify bladder injury. Both of these methods highlight the importance of distending the bladder at the time of imaging. The characteristic finding of an extraperitoneal bladder rupture is flamed shape extravasation of contrast into the pelvis ( Fig 1.13-2 ). An intraperitoneal rupture is characterized by the outlining of bowel loops or filling the paracolic gutters ( Fig 1.13-3 ). In patients with microscopic hematuria with an associated pelvic fracture, diagnostic imaging should be performed, if other signs and symptoms are present.

2.2 Decision making in acute management

The diagnosis, timing of imaging, and subsequent management of bladder injuries should be guided by the hemodynamic stability of the patient. During the Advanced Trauma and Life Support Secondary Survey, the trauma team should maintain a high index of suspicion for a bladder injury in a patient with a pelvic fracture. A CT cystogram needs to be obtained since conventional abdominal/pelvic CT scan is inadequate for bladder evaluation [2]. The bladder must be retrogradely filled. It is inadequate to clamp the urethral catheter to attempt antegrade filling of the bladder with intravenous contrast.