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30. Urologic Trauma
Keywords
TraumaKidneyUreteralBladderUrethralGenitalIntroduction
Trauma can be defined as any physical injury to living tissue caused by an extrinsic agent. It is the sixth leading cause of death worldwide, accounting for 10% of all mortalities [1]. Injury is most often related to car accidents and personal injury. Trauma has a male predominance. Geographic and socioeconomic variation greatly impacts the causes and effects of traumatic injuries [2].
Urologic injuries may occur during severe trauma, requiring a multidisciplinary approach for management. The Urologist remains an important consultant to the trauma team, ensuring accurate radiographic evaluation of urogenital structures and acting as the steward for preserving genitourinary function. In the context of urotrauma patients, urologists must be familiar with open and minimally invasive surgical techniques in order to control bleeding and/or obtain timely urinary drainage [3].
Isolated urologic injuries are rare because the kidneys, ureters and bladder are well protected. While the penis and testicles are mobile, they are also rarely affected. More commonly, urologic injuries are concomitant with major abdominal trauma events; urologic organs are involved in 10% of abdominal traumas [4].
Classification of Trauma
WHO classification of injuries
Type of injuries | |
|---|---|
Intentional | Self—Inflicted |
Interpersonal violence | |
War-related | |
Unintentional | Road traffic |
Poisoning | |
Falls | |
Fires | |
Drowning | |
Penetrating trauma is also classified according to the velocity of the projectile into:
High-velocity (rifle bullets) inflict severe damage due to extreme shear forces.
Medium velocity (handgun bullets) damage is usually confined to the projectile tract.
Low velocity (knife stab) inflict focal trauma without heat effects.
Blast injuries combines both blunt and penetrating trauma, and also may be accompanied by a burn injury [5]. Because of varied tissue effects, understanding the mechanism of the trauma, type and caliber of weapon impacts management. Blunt injuries occur through different mechanisms such as crush, transmission of a stress wave via compressive forces, or shear injury due to deceleration. These mechanisms explain multiple intra-abdominal organ injuries that are not in close proximity to each other [6].
Initial Management
The Airway, Breathing, Circulation, Disability, Exposure (ABCDE) approach is a systematic way to immediately assess and treat injured patients [7]. Initial evaluation must include hemorrhage control, basic stabilization of the patient, intravenous fluids, and drainage catheters. As much information about the mechanism of trauma and the patient’s medical history should be collected. Abdominal and genital palpation as well as searching for bruises and hematomas may reveal a lesion in the retroperitoneum or pelvis. Lower rib fractures should lead to suspicion of renal injuries. Pelvic fractures may be related to bladder and urethral injuries. Diffuse abdominal pain could be related to intraperitoneal organ perforation, bleeding or intraperitoneal urine extravasation. In males prior to insertion of a urinary catheter, check for the presence of blood at the meatus [8].
Renal Trauma
Renal trauma accounts for approximately 1–5% of all trauma and approximately 10% of abdominal trauma [9]. The kidney is protected by lumbar muscles, ribs and Gerota’s fascia/peri/para nephric adipose tissue. Blunt trauma to the abdomen or back is the most common cause of renal trauma, accounting for 80–85% of all renal lesions [5]. Additionally, a direct blow to the flank during sports activities can cause renal trauma. This occurs most frequently in biking (31%), baseball and softball (9.3%) and football injuries (6.5%) [10].
Sudden deceleration or a crush injury may result in a contusion or laceration of the parenchyma and renal hilum, but renal vascular injuries in blunt trauma are rare (<5%). Isolated renal artery injury is also rare, but renal artery occlusion is associated with rapid deceleration [11]. Penetrating trauma includes gunshot and stab wounds as the most representative causes and are less predictable and more severe than blunt trauma. Projectiles and bullets can cause more parenchymal destruction and compromise multiple organs [12].
Classification
1989 AAST OIS Classification
Grade | Injury description |
|---|---|
I | |
Contusion | Microscopic or gross hematuria, urological studies normal |
Hematoma | Subcapsular, nonexpanding without parenchymal laceration |
II | |
Hematoma | Nonexpanding perirenal hematoma confined to renal retroperitoneum |
Laceration | <1.0 cm parenchymal depth of renal cortex, without collecting system rupture or urinary extravasation |
III | |
Laceration | >1.0 cm parenchymal depth of renal cortex, without collecting system rupture or urinary extravasation |
IV | |
laceration | Parenchymal laceration extending through the renal cortex, medulla, and collecting system |
Vascular | Main renal artery or vein injury with contained hemorrhage |
V | |
Laceration | Completely shattered kidney |
Vascular | Avulsion of renal hilum which devascularizes kidney |
Revised Injury Scaling Classification
Grade | Injury definition |
|---|---|
I | |
Parenchyma | Subcapsular hematoma and/or contusion |
Collecting system | No injury |
II | |
Parenchyma | Laceration <1 cm in depth and into cortex, small hematoma contained within Gerota’s fascia |
Collecting system | No injury |
III | |
Parenchyma | Laceration >1 cm in depth and in medulla, hematoma contained within Gerota’s fascia |
Collecting system | No injury |
IV | |
Parenchyma | Laceration through the parenchyma into the urinary collecting system |
Vascular segmental vein or artery injury | |
Collecting system | Laceration, one or more into the collecting system with urinary extravasation |
Renal pelvis laceration and/or complete ureteral pelvic disruption | |
V | |
Vascular | Main renal artery or vein laceration or avulsion main renal artery or vein thrombosis |
Authorized from: The Journal of Trauma and Acute Care Surgery,” Revision of Current American Association for the Surgery of Trauma Renal Injury Grading System”.
Diagnostic Tools
Blunt trauma to the back, flank, lower thorax or upper abdomen may involve the kidneys. Flank pain, ecchymoses, abrasions, fractured ribs, abdominal distension or palpating a mass may raise the suspicion for renal compromise. In penetrating injuries, entry and exit wounds should be found. Wounds in the lower thoracic back, flanks or upper abdomen may involve the kidneys. Be aware that for a stab wound, the extent of the entrance wound may not accurately reflect the depth of penetration [5]. Moreover, blast injury may extend beyond the entry and exit points, and the route of bullets may be unpredictable.
Labs, Imaging
Initial laboratories required are hematocrit, baseline creatinine and urinalysis. Major injuries such as disruption of the UPJ, pedicle injuries, segmental arterial thrombosis and stab wounds may not present with hematuria [16]. While urine dipstick is a rapid test to screen for hematuria, the rate of false negatives are 3–10% [17]. Serial measurement of hematocrit is part of continuous trauma evaluation along with the response to resuscitation; a decrease in hematocrit and requirement of blood transfusions may indicate a major renal injury. Serum creatinine on presentation usually reflects renal function prior to the injury; an increased level usually reflects pre-existing renal pathology as creatinine is a lagging indicator of renal health [5]. New markers of acute renal injury such as cystatin-C, cysteine-rich protein-61 (CYR-61), ELISA, Interleukin-18 (IL-18) may have an increasing role in diagnosing acute renal compromise [18].
When a renal lesion is suspected the aims of imaging are: grade the injury, identify injuries to other organs, confirm presence of the contralateral kidney, and document pre-existing renal pathology. Renal imaging should be undertaken in patients with blunt trauma, visible and non-visible hematuria and hypotension (systolic blood pressure <90 mm Hg) [3, 5]. Imaging is recommended in patients with rapid deceleration injury, direct flank trauma, flank contusions, lower ribs fractures and lesions to the thoracolumbar spine, and in penetrating trauma with or without hematuria [19–21].
Computed tomography (CT) with immediate and delayed phases is the imaging modality of choice and can identify and grade renal lesions. Arterial phase images allow assessment of vascular injuries and extravasation of contrast, while the delayed phase identifies collecting system or ureteral injury [22]. Although the AAST system of grading is primarily based on surgical findings, a good correlation with CT appearance has been demonstrated [23].
The intraoperative pyelography, or “One-shot”, consists of a bolus of intravenous contrast media (2 mL/kg) followed by a single plain film taken after 10–15 min. This remains a useful technique to confirm the presence of a functioning contralateral kidney, in particular for patients too unstable to undergo a CT. Utility of this exam can be hampered by the presence of warming blankets, retractors or laparotomy sponges; also, under resuscitation leads to poor contrast excretion [24, 25].
Ultrasonography is not considered appropriate in the initial evaluation due to poor sensitivity. Studies have demonstrated that ultrasonography may be inaccurate in detecting solid organ trauma. Usually in the blunt trauma scenario, Focus Assessment with Sonography for Trauma (FAST) exam in an unstable patient is negative [26]. Magnetic resonance imaging (MRI) accuracy is similar to CT, but the logistical of moving a trauma patient, the length of time to scan, and the need for MRI-safe equipment make its routine use impractical. Radionuclide scans also do not play a role in the acute evaluation of renal trauma.
Management
Blunt injuries: Non-surgical treatment is the recommendation of choice. All grade 1, 2 and 3 injuries can be managed non-operatively. In stable patients primary conservative management consists of supportive care with bed rest, hemodynamic observation, blood transfusion as needed, and is associated with lower rate of nephrectomies and preservation of renal function [27]. Patients with grade 4 and 5 injuries with concomitant major injuries usually undergo exploration and sometimes require nephrectomy. Despite the variability in different medical centers and the comfort level with the management of renal trauma, the conservative approach is still favored. As it is stated in the AUA Guidelines, there is Grade B Evidence regarding the observational management of hemodynamically stable patients. Grade 5 vascular injuries should be managed with immediate nephrectomy in cases of hypotension refractory to transfusion to stem the risk of exsanguination [28]. Approximately 25% of blunt injuries are high-grade injuries, meaning grade 4 or 5. Actual data indicates that many of these patients can be treated with observation, especially in hemodynamically stable patients regardless of injury grade [29]. A conservative approach in these patients is not associated with prolonged hospital stay [30].
Angioembolization has a central role in the non-surgical management of stable patients who continue to bleed. It has been utilized in all grades of trauma and most beneficial in grades 4 or greater [31]. The criteria for angiography and embolization in a patient with renal hemorrhage include persistent bleeding from a renal segmental artery with or without parenchymal laceration, hemodynamic instability with grade 3–4 injury, arteriovenous fistula or pseudoaneurysm, persistent gross hematuria and/or rapidly decreasing hematocrit requiring 2 units of blood [32]. This procedure can be as successful in up to 94.9% grade 3, 89% grade 4 and 52% grade 5 injuries [31].
Penetrating injuries: In all grade 1 and 2 injuries management is non-operative as outlined above. Traditionally penetrating injuries have been treated surgically based on a full evaluation of clinical, laboratory and radiological factors. In selected stable patients, non-operative management has been successful, and treatment depends on the extent and grade of injury. Gunshot injuries must be explored if the renal hilum is involved, in the presence of ureteral lesion, or renal pelvis lacerations [5]. Low-velocity gunshot and stab wounds can be managed conservatively, conversely tissue damage in high-velocity gunshot may ultimately require a nephrectomy. Non-surgical management has been documented with successful outcomes between 50 to 100%, with rates of nephrectomy of 24%, that can increase to 72% if the retroperitoneum is explored [33].
Surgical management: Treatment of renal injuries may be influenced by the decision to explore associated abdominal injuries. Hemodynamic instability and unresponsiveness to aggressive resuscitation due to renal hemorrhage is an indication for surgical intervention. Moreover, finding an expanding or pulsatile peri-renal hematoma during an exploratory laparotomy performed for associated injuries is an indication to act [5]. The main objective of surgical intervention is control of bleeding and renal preservation. A transperitoneal approach is recommended and access to the pedicle may be obtained through the posterior parietal peritoneum, which is incised over the aorta, medial to the inferior mesenteric vein. Alternatively, initially dissect the psoas muscle fascia adjacent to the great vessels with blunt dissection and upon identification of the aorta, the dissection is continued superiorly until the renal vein is identified. Once identified the artery is occluded, if bleeding persists the vein is then clamped. Once vascular control is achieved, the colon is reflected to incise Gerota’s fascia laterally and evacuate the hematoma. The entire kidney must be exposed to examine the renal pelvis, parenchyma and vessels [5, 9, 34].
The reconstruction process starts with debridement; all non-viable tissue should be removed. Parenchymal vessels must be closed with absorbable sutures; veins can be ligated freely. While ligation of arteries may lead to renal infarction, persistent bleeding usually stops when the parenchymal defect is closed. Watertight closure of the collecting system must be done. Re-approximation of the capsule will close the defect and prevent urinary extravasation. When this is not possible, a pedicle flap of omentum is an excellent alternative, secured over the defect with absorbable sutures. Lesions to the upper or lower pole may be treated with partial nephrectomy, with the same principles of bleeding control, collecting system and capsule closure if possible. Lesions to the mid portion follows the same principles above described, and instead of omentum, placement of Gelfoam can improve hemostasis [9]. When a contained hematoma is founded several authors recommend to avoid Gerota’s fascia exploration, the supporting theory is that given their confined retroperitoneal location and Gerota’s protection, it functions as an innate tamponade mechanism to control excessive bleeding and urinary extravasation. When Gerota’s fascia is opened, the hematoma is no longer contained and may lead to more bleeding and need for nephrectomy [35].
Follow up in trauma patients includes physical examination, serial blood pressure measurement, urinalysis and serum renal function. Radiological studies must be individualized, depending on the degree of trauma. As mentioned, grades 1–3 do not require imaging follow up as long as they remain clinically well. The usefulness of frequent CT scan has never been proved. Guidelines recommend repeat imaging 2–4 days after trauma to minimize the risk of missed complications [5]. This should always be done in patients with fever, unexplained decrease of hematocrit, significant flank pain, suspicion of a urinoma or fistula. If fistula or urinoma is detected, immediate urinary drainage with a ureteral stent and/or percutaneous drainage of urinoma or percutaneous nephrostomy may be considered [3].
Ureteral Trauma
Ureteral injuries are rare, accounting for 1–2.5% of genitourinary trauma. Acute ureteral injury is most likely to occur in an iatrogenic fashion (80%) vs. occurrences related to violent trauma like stab wounds or gunshots (20%). Exposure to an agent (ureterolithiasis or recurrent instrumentation) or a treatment (radiation) can also be considered a cause of ureteral trauma [36, 37]. Procedures involving the ureter or near the ureter are frequent, so iatrogenic ureteral injuries are relatively common.
Gynecological surgery accounts for over half of all iatrogenic ureteric injuries [38]. Colorectal operations such as abdominoperineal resection or low anterior resection may particularly increase the risk of injury given the complexity of resection [39, 40]. Common types of injuries in order of frequency include: ligation, kinking by suture, transection/avulsion, partial transection, or crush and devascularization with delayed necrosis/stricture. The pelvic ureter is compromised in 80% of these injuries, and this has not been shown to be prevented by placing a preoperative stent [40]. Routine prophylactic stenting is generally not cost effective and does not decrease the rate of injury [5, 41], but may improve detection of the ureter and identify the injury [38]. In acute trauma, a high degree of clinical suspicion is required for ureteral injury. In particular with deceleration injury, ureteral injury may occur in 10% of cases, most frequently proximally or mid-ureter. The likelihood of distal ureteric injury is low because this region is protected by the bony pelvis [5, 37, 41].
Ureter injury scale
Grade | Injury definition |
|---|---|
I | |
Hematoma | Contusion or hematoma without devascularization |
II | |
Laceration | <50% transection |
III | |
Laceration | >50% transection |
IV | |
Laceration | Complete transection with <2 cm devascularization |
V | |
Laceration | Avulsion with >2 cm of devascularization |
In a delayed scenario, iatrogenic trauma usually is detected when there is evidence of urinary obstruction, urinary fistulae formation or sepsis. There are clinical signs characteristic of a delayed diagnosis: flank pain, vaginal drainage, urinary leakage, hematuria, fever, urinoma or urinary incontinence [5, 37]. When possible, a sample of draining fluid can be sent to the laboratory for a fluid creatinine level to confirm urinary fistula. Early recognition facilitates immediate repair and provides better outcome [42].
CT with 10-min delayed images is the diagnostic tool of choice both in iatrogenic and penetrating stable patients. Findings suggestive of ureteral injury may include contrast extravasation, delayed pyelogram, hydronephrosis and lack of contrast in the ureter distal to the injury [3, 5].
Reconstructive options for the ureter depend on the location and length of injury. A key principle for reconstruction is a lack of tension on the repair. Proximal ureter injuries shorter than 3 cm may be managed with a uretero-ureterostomy. When that seems ill advised, an uretero-calycostomy may be considered. If the lesion is extensive, a transuretero-ureterostomy is a valid option. In extended lesions or complete ureteral injury, a segment of intestine, appendiceal or fallopian tube could be considered as replacement. Also, auto transplantation may be considered. For injuries in the mid ureter, uretero-ureterostomy or a Boari flap would be options. Distal injuries should be managed with ureteral re-implant (uretero-neocystostomy). Due to the vascular compromise of the distal ureter a primary anastomosis is not recommended as the primary surgical approach. The use of stents in the repair has been controversial related to stricture formation, inflammatory reaction and discomfort, but others advocate for their use in that benefits outweigh the risks [41].
In trauma patients with suspected ureteral injury that requires a laparotomy, direct inspection must be performed. This is especially true in cases during which a proper radiological study has not yet been performed. If a lesion is founded, immediate repair must be done. In unstable patients temporary urinary drainage and delayed definitive management is recommended [3]. The ureter can be clipped or tied off and percutaneous nephrostomy tube planned.
Bladder Trauma
Bladder trauma is considered the most frequent of the lower urinary tract injuries. The major cause of bladder injury is blunt trauma accounting for 85% [41] and is most often related to motor vehicle collisions, falls, industrial trauma/pelvic crush injuries and blows to the lower abdomen [5]. Pelvic fractures are associated with bladder trauma in 3.6% of cases, of those intraperitoneal varies from 14 to 50% and extraperitoneal 44–68% among series [43, 44]. Penetrating trauma accounts for 14–49% of bladder trauma; gunshot wounds comprise 88% of all bladder trauma [40]. Also, iatrogenic injuries during abdominal surgery can cause bladder trauma.
Classification
Bladder injury scale
Grade | Injury definition |
|---|---|
I | |
Hematoma | Contusion, intramural hematoma |
Laceration | Partial thickness |
II | |
Laceration | Extraperitoneal bladder wall laceration <2 cm |
III | |
Laceration | Extraperitoneal (>2 cm) or intraperitoneal (<2 cm) bladder wall laceration |
IV | |
Laceration | Intraperitoneal bladder wall laceration >2 cm |
V | |
Laceration | Intraperitoneal or extraperitoneal bladder wall laceration extending into the bladder neck or ureteral orifice (trigone) |
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