Bladder Trauma

Etiology

Bladder trauma occurs in the setting of motor vehicle collisions (MVC), work-related instances, and violent crimes, but also can be iatrogenic. Two main mechanisms of blunt bladder injury are high energy blow to the lower abdomen while the bladder is distended, which usually results in an IP injury, and trauma causing pelvic fractures, which usually results in an EP bladder injury. As such, bladder trauma commonly occurs with concomitant orthopedic and abdominopelvic visceral injuries. Researchers found traumatic bladder rupture accounts for 1.6% of blunt abdominopelvic trauma cases.[3] There are challenges associated with consistent results regarding bladder trauma. For example, there is evidence that approximately 85% of bladder injuries result from blunt trauma, while incident rates can account for up to 51% of injuries result from penetrating trauma.[4][5] While the national incidence of penetrating injuries in 2015 was less than 10%, the incidence of bladder injuries resulting from penetrating injuries can be much higher.[4][6] Additionally, other less common etiologies of bladder trauma include iatrogenic injuries most commonly during obstetric, gynecologic, or urologic procedures.

Epidemiology

While extraperitoneal (EP) and intraperitoneal bladder (IP) injuries occur with blunt and penetrating traumas, iatrogenic bladder injuries are well-documented as well. EP bladder injuries account for 60% of bladder traumas, while 30% are intraperitoneal, and 10% are combined.[1] Iatrogenic IP bladder injuries are not uncommon. The bladder is the most frequently injured organ in obstetric/gynecologic procedures such as cesarean section and hysterectomies, with an incidence of 13.8 cases per 1000 procedures.[7]

Pathophysiology

The bladder is located in the anterior pelvis in an adult. The dome is covered by the peritoneum, and the bladder neck is fixed to the pelvis by fascia and ligaments. IP bladder rupture occurs on the dome of the bladder and above the peritoneal reflection, while EP bladder rupture occurs below the peritoneal reflection and on the anterior or lateral aspects of the bladder.

Bladder contusion is a partial thickness tear of the bladder and the formation of a hematoma caused by blunt trauma. Patients with bladder contusion can present with gross hematuria. On cystography, there is no extravasation of contrast. This is usually self-limiting, as it is a relatively benign process.EP bladder rupture is most often caused by rapid deceleration. A combination of shearing force and direct penetration by bony spicules of a fractured pelvis is thought to be the underlying mechanism of EP bladder rupture. Complex EP bladder rupture can cause urine leaks into the thighs, penis, perineum, or the anterior abdominal wall. Researchers found that 85% to 100% of bladder injuries are associated with concomitant pelvic fractures.[5]

IP bladder rupture occurs most commonly on the dome of the bladder as it is the only portion covered by the peritoneum; thus, it is the least protected area of the bladder. Contrary to EP bladder rupture, IP bladder rupture is usually caused by a direct blow to a distended bladder, although it can also be associated with deceleration injuries. Urine drains into the abdomen and is absorbed by the peritoneal cavity, manifesting as elevated blood urea nitrogen and creatinine, electrolyte and metabolic derangements, and decreased urine output. Combined EP and IP bladder rupture are less common, accounting for 5% to 8% of bladder injuries associated with pelvic fractures.[3]

History and Physical

Evaluation of a patient with trauma starts with the primary survey, which consists of the airway, breathing, circulation, disability, and exposure. The secondary survey includes a head-to-toe exam. Findings in the secondary survey may suggest bladder trauma includes pelvic instability, blood at the meatus, significant abdominal and pelvic pain, suprapubic tenderness, high riding prostate, and gross hematuria. An unstable pelvic fracture is associated with a high prevalence of massive internal bleeding into the pelvis and should be stabilized with a pelvic binder before surgical intervention. Peritoneal signs such as rigidity, guarding, and rebound tenderness should raise the suspicion not only for perforated viscus in the abdomen but also intraperitoneal bladder injury. The focused assessment with sonography in trauma (FAST) exam can be used to quickly assess for pericardial, intra-abdominal, and pelvic free fluid; however, FAST exams cannot distinguish between blood and urine. Evaluation of the genitals may reveal blood at the urethral meatus, in which case urethral injury needs to be ruled out before inserting an indwelling catheter. A high riding prostate on a rectal exam is also a concern for urethral injury. Gross hematuria is seen in 67% to 95% of cases and is the most classical symptom associated with bladder trauma.[8]

Evaluation

Basic labs such as complete blood count, metabolic panel, coagulation panel, and urinalysis should be obtained as part of the trauma work-up. Retrograde cystography, either computed tomography (CT) or conventional X-ray, is indicated for hemodynamically stable patients with gross hematuria, blood at the meatus, inability to void, pelvic fracture with microscopic hematuria, or penetrating injury to the pelvis, buttock, or lower abdomen. Conventional X-ray and CT cystography have similar sensitivity and specificity. Intravenous contrast CT scan with a delayed phase is less sensitive and specific than retrograde cystography in detecting bladder trauma.[9] According to the European Association of Urology guidelines for urogenital trauma, CT cystography is preferred over traditional X-ray cystography due to rapid turnover time and convenience. Another advantage of CT cystography over conventional cystography is that it is superior in detecting other intra-abdominal processes and bony fragments within the bladder.[10] Imaging findings associated with EP bladder trauma are extravasation of contrast around the base of the bladder confined to the perivesical space and extravasation into the thighs, penis, perineum, or anterior abdominal wall if the urogenital fascia is violated in a complex injury. In IP bladder trauma, contrast extravasates into the peritoneal cavity, outlining the loops of the bowel and filling paracolic gutters. Methylene blue or indigo carmine helps assess suspected bladder injury or evaluate bladder repair intraoperatively.[9]

Treatment / Management

According to the American urological association (AUA) guidelines for bladder rupture, IP bladder rupture is repaired surgically while uncomplicated EP bladder rupture may be treated with catheter drainage. If a retrograde urethrogram shows urethral injury, a suprapubic catheter is placed either via a percutaneous or an open approach.

Surgical intervention is indicated for IP bladder injury due to the risk of intra-abdominal sepsis. In hemodynamically stable patients with isolated IP bladder injury, diagnostic laparoscopy with repair can be considered. Intramural bladder hematoma is left undisturbed as releasing the tamponade effect can lead to significant hemorrhage. The bladder lumen is inspected, any foreign body is removed, and nonviable tissue is debrided. An indwelling catheter is placed before repair. The bladder is classically repaired in two layers with running absorbable suture. Watertight closure is ensured with irrigation by filling the bladder in a retrograde fashion through a urinary catheter. The bladder can also be filled in a retrograde fashion with methylene blue to identify leaks. A pelvic drain may be also be placed in the perivesical space. The abdominal wall layers and skin are closed. Postoperatively, the patient should be placed on broad-spectrum intravenous antibiotics for 24-hours in cases of penetrating injury. The pelvic drain may be removed if it has low output. The indwelling catheter can be removed after 10 to 14 days, and a cystogram is performed before removal, as described earlier.

Uncomplicated EP bladder injury without urethral injury is managed non-operatively with an indwelling catheter for 10 to 14 days and antibiotic prophylaxis. Before removal of the catheter, a repeat retrograde cystography is performed to ensure healing of the injury. If extravasation continues greater than three months after the traumatic event, the injury should be surgically repaired. Indications for operative management EP bladder injury include concomitant vaginal or rectal injury, foreign body in the bladder wall, or orthopedic repair involving hardware.[11]

Differential Diagnosis

When assessing a patient with bladder trauma following differentials should be kept in mind.

• Penile trauma
• Testicular trauma
• Vaginal trauma
• Urethral trauma
• Pelvic fractures – acetabular, open book, straddle, or pelvic avulsion
• Retroperitoneal hemorrhage
• Renal trauma
• Ureteral trauma

Prognosis

Patients with bladder injuries may also present with a wide variety of concurrent traumatic injuries. A single-center retrospective study at a level I trauma center found a mortality rate of 10.8% among patients with bladder rupture undergoing laparotomy for trauma.[2] Untreated bladder rupture can lead to complications such as peritonitis, severe sepsis, and fistulas. Successful management requires timely evaluation, accurate diagnosis, and proper management based on the location and severity of the rupture. Most patients recover normal bladder function. Severe trauma involving the neck of the bladder, the urethra, or pelvic floor muscles may lead to urinary incontinence that may or may not be amenable to surgery.

Complications

Complications can occur either due to bladder trauma itself or due to surgery for bladder repair. Following complications can occur:

• Urinary incontinence
• Wound dehiscence; drainage from wound site should not be confused with urine leak
• Decreased bladder capacity from over-debridement
• Persistent urinary extravasation
• Hemorrhage can occur with violation of pelvic hemorrhage
• A pelvic abscess can develop from an infected hematoma
• Intraabdominal infection
• Fistula
• Urinary tract infection
• Urinary urgency