Excerpt from Bladder Trauma

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Bladder injuries occur as a result of blunt or penetrating trauma. The probability of bladder injury varies according to the degree of bladder distention; therefore, a full bladder is more likely to become injured than an empty one.

Although uniformly fatal in the past, a timely diagnosis with appropriate medical and surgical management now offers an excellent outcome. Early clinical suspicion, appropriate and reliable radiologic studies, and prompt surgical intervention, when indicated, are the keys to successful diagnosis and management.

For excellent patient education resources, visit eMedicine's Kidneys and Urinary System Center and Procedures Center. Also, see eMedicine's patient education articles Blood in the Urine, Intravenous Pyelogram, Cystoscopy, and Foley Catheter.

History of the Procedure

Patients with signs and symptoms suggestive of a bladder injury have a history typical for pelvic trauma, which is fairly straightforward for motor vehicle accidents, deceleration injuries, or assaults to the lower abdomen. If the patient is unconscious, family members or, more often, emergency services personnel can provide the history.

• Bladder injury from a motor vehicle accident may occur from direct impact with the car or indirectly from the steering wheel or seatbelt.
• Deceleration injuries of the urinary bladder usually result from falling from a great height and landing on unyielding ground.
• Assault to the lower abdomen by a sharp kick or blow may result in a bladder perforation.
• Penetrating injuries to the bladder usually result from high-velocity gunshots or sharp stab wounds to the suprapubic area.

Problem

Blunt trauma

Deceleration injuries usually produce both bladder trauma (perforation) and pelvic fractures. Approximately 10% of patients with pelvic fractures also have significant bladder injuries. The propensity of the bladder to sustain injury is related to its degree of distention at the time of trauma.

Penetrating trauma

Assault from a gunshot or stabbing typifies penetrating trauma. Often, concomitant abdominal and/or pelvic organ injuries are present.

Obstetric trauma

During prolonged labor or a difficult forceps delivery, persistent pressure from the fetal head against the mother's pubis can lead to bladder necrosis. Direct laceration of the urinary bladder is reported in 0.3% of women undergoing a cesarean delivery. Previous cesarean deliveries with resultant adhesions are a risk factor. Undue scarring may cause obliteration of normal tissue planes and facilitate an inadvertent extension of the incision into the bladder. Unrecognized bladder injuries may lead to vesicouterine fistulas and other problems.

Gynecologic trauma

Bladder injury may occur during a vaginal or abdominal hysterectomy. Blind dissection in the incorrect tissue plane between the base of the bladder and the cervical fascia results in bladder injury.

Urologic trauma

Perforation of the bladder during a bladder biopsy, cystolitholapaxy, transurethral resection of the prostate (TURP), or transurethral resection of a bladder tumor (TURBT) is not uncommon. Incidence of bladder perforation is reportedly as high as 36% following bladder biopsy.

Orthopedic trauma

Orthopedic pins and screws can commonly perforate the urinary bladder, particularly during internal fixation of pelvic fractures. Thermal injuries to the bladder wall may occur during the setting of cement substances used to seat arthroplasty prosthetics.

Idiopathic bladder trauma

Patients diagnosed with alcoholism and those individuals who chronically imbibe a large quantity of fluids are susceptible to this type of injury. Previous bladder surgery is a risk factor. In reported cases, all bladder ruptures were intraperitoneal. This type of injury may result from a combination of bladder overdistention and minor external trauma (eg, a simple fall).

Frequency

Frequency of bladder rupture varies according to the following mechanisms of injury:

• External trauma (82%)
• Iatrogenic (14%)
• Intoxication (2.9%)
• Spontaneous ( <1%)

Of all bladder injuries, 60-85% are from blunt trauma and 15-40% are from a penetrating injury. The most common mechanisms of blunt trauma are motor vehicle accidents (87%), falls (7%), and assaults (6%). In penetrating traumas, the most frequent culprit is gunshot wounds (85%), followed by stabbings (15%).

Approximately 10-25% of patients with a pelvic fracture also have urethral trauma. Conversely, 10-29% of patients with posterior urethral disruption have an associated bladder rupture.

Traumatic bladder ruptures

Of traumatic ruptures, extraperitoneal bladder perforations account for 50-71%, intraperitoneal accounts for 25-43%, and combined perforations account for 7-14%. Incidence of intraperitoneal bladder ruptures is significantly higher in children because of the predominantly intra-abdominal location of the bladder prior to puberty.

Combined intraperitoneal and extraperitoneal ruptures account for approximately 10% of all traumatic bladder-perforating injuries. Mortality rates in these patients approach 60%, as compared to 17-22% overall, reflecting the severity of concomitant injuries associated with combined bladder ruptures.

Associated bowel injuries

Incidence is reportedly as high as 83% in patients with gunshot wounds. Colon injuries are reported in 33% of patients with stab wounds, and vascular injuries are reportedly as high as 82% in patients with a penetrating trauma (with a 63% mortality rate).

Etiology

Main causes of bladder injury are penetrating and blunt trauma. Iatrogenic causes include surgical misadventures from gynecologic, urologic, and orthopedic operations near the urinary bladder. Less common causes involve obstetric trauma. Spontaneous or idiopathic bladder injuries without an obvious underlying pathology constitute the remainder.

Pathophysiology

Bladder contusion is an incomplete or partial-thickness tear of the bladder mucosa. A segment of the bladder wall is bruised or contused, resulting in localized injury and hematoma. Contusion typically occurs in the following clinical situations:

• Patients presenting with gross hematuria after blunt trauma and normal imaging studies
• Patients presenting with gross hematuria after extreme physical activity (ie, long-distance running)

The bladder may appear normal or teardrop shaped on cystography. Bladder contusions are relatively benign, are the most common form of blunt bladder trauma, and are usually a diagnosis of exclusion. Bladder contusions are self-limiting and require no specific therapy, except for short-term bed rest until hematuria resolves. Persistent hematuria or unexplained lower abdominal pain requires further investigation.

Extraperitoneal bladder ruptures

Traumatic extraperitoneal ruptures usually are associated with pelvic fractures (89-100%). Previously, the mechanism of injury was believed to be from a direct perforation by a bony fragment or a disruption of the pelvic girdle. It is now generally agreed that the pelvic fracture is likely coincidental and that the bladder rupture is most often due to a direct burst injury or the shearing force of the deforming pelvic ring.

These ruptures usually are associated with fractures of the anterior pubic arch, and they may occur from a direct laceration of the bladder by the bony fragments of the osseous pelvis. The anterolateral aspect of the bladder typically is perforated by bony spicules. Forceful disruption of the bony pelvis and/or the puboprostatic ligaments also tear the wall of the bladder. The degree of bladder injury is directly related to the severity of the fracture.

Some cases may occur by a mechanism similar to intraperitoneal bladder rupture, which is a combination of trauma and bladder overdistention. The classic cystographic finding is contrast extravasation around the base of the bladder confined to the perivesical space; flame-shaped areas of contrast extravasation are noted adjacent to the bladder. The bladder may assume a teardrop shape from compression by a pelvic hematoma. Starburst, flame-shape, and featherlike patterns also are described.

With a more complex injury, the contrast material extends to the thigh, penis, perineum, or into the anterior abdominal wall. Extravasation will reach the scrotum when the superior fascia of the urogenital diaphragm or the urogenital diaphragm itself becomes disrupted.

If the inferior fascia of the urogenital diaphragm is violated, the contrast material will reach the thigh and penis (within the confines of the Colles fascia). Rarely, contrast may extravasate into the thigh through the obturator foramen or into the anterior abdominal wall. Sometimes, the contrast may extravasate through the inguinal canal and into the scrotum or labia majora.

Intraperitoneal bladder rupture

Classic intraperitoneal bladder ruptures are described as large horizontal tears in the dome of the bladder. The dome is the least supported area and the only portion of the adult bladder covered by peritoneum. The mechanism of injury is a sudden large increase in intravesical pressure in a full bladder. When full, the bladder's muscle fibers are widely separated and the entire bladder wall is relatively thin, offering relatively little resistance to perforation from sudden large changes in intravesical pressure.

Intraperitoneal bladder rupture occurs as the result of a direct blow to a distended urinary bladder. Resulting increase in intravesical pressure causes a horizontal tear along the intraperitoneal portion of the bladder wall. This is the weakest part of the bladder, since its muscle fibers are most widely separated. This type of injury is common among patients diagnosed with alcoholism or those sustaining a seatbelt or steering wheel injury.

Since urine may continue to drain into the abdomen, intraperitoneal ruptures may go undiagnosed from days to weeks. Electrolyte abnormalities (eg, hyperkalemia, hypernatremia, uremia, acidosis) may occur as urine is reabsorbed from the peritoneal cavity. Such patients may appear anuric, and the diagnosis is established when urinary ascites are recovered during paracentesis.

Intraperitoneal ruptures demonstrate contrast extravasation into the peritoneal cavity, often outlining loops of bowel, filling paracolic gutters, and pooling under the diaphragm. An intraperitoneal rupture is more common in children because of the relative intra-abdominal position of the bladder. The bladder descends into the pelvis usually by the age of 20 years.

Combination of intraperitoneal and extraperitoneal ruptures

Cystogram reveals contrast outlining the abdominal viscera and perivesical space. External penetrating injuries deserve special mention. A penetrating injury of the urinary bladder results from a high-velocity bullet traversing the bladder, knife wounds, or impalement by various sharp objects. These may result in intraperitoneal, extraperitoneal, or a combined bladder injury.

The high incidence of associated injury to abdominal viscera and vascular structures mandates surgical exploration in virtually every case. Often, the cystogram is bypassed, and the diagnosis is made during an exploratory laparotomy. Cystogram results may be falsely negative in patients with penetrating bladder injuries secondary to small-caliber bullet wounds. In such patients, these injuries may not be appreciated until exploratory surgery is performed.

Clinical

Clinical signs of bladder injury are relatively nonspecific; however, a triad of symptoms is often present (eg, gross hematuria, suprapubic pain or tenderness, difficulty or inability to void).

Most patients with bladder rupture complain of suprapubic or abdominal pain, and many can still void; however, the ability to urinate does not exclude bladder injury or perforation. Hematuria invariably accompanies all bladder injuries. Gross hematuria is the hallmark of a bladder rupture. More than 98% of bladder ruptures are associated with gross hematuria, and 10% are associated with microscopic hematuria; conversely, 10% of patients with bladder ruptures have normal urinalyses.

An abdominal examination may reveal distention, guarding, or rebound tenderness. Absent bowel sounds and signs of peritoneal irritation indicate a possible intraperitoneal bladder rupture.

In the setting of a motor vehicle accident or a crush injury, bilateral palpation of the bony pelvis may reveal abnormal motion indicating an open-book fracture or a disruption of the pelvic girdle.

If blood is present at the urethral meatus, suspect a urethral injury. Perform a retrograde urethrogram to assess the integrity of the urethra before attempting to blindly pass a Foley catheter.

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