Chapter 16 – Genitourinary Trauma




Abstract




The genitourinary (GU) system includes the kidneys, ureters, bladder, urethra, penis, scrotum, and female genitalia. Of the 27.7 million patients per year presenting to emergency departments (ED) for traumatic injury, about 10% of these traumas primarily involve the GU system, and another 10–15% of patients with abdominal trauma will have GU injuries as well.1 GU trauma patients are predominantly young (80% less than the age of 45 years) and male (85% of all patients).2 Delays or missed diagnosis of GU trauma can result in increased morbidity and mortality due to preventable complications with long term consequences.3





Chapter 16 Genitourinary Trauma



E. Liang Liu


The genitourinary (GU) system includes the kidneys, ureters, bladder, urethra, penis, scrotum, and female genitalia. Of the 27.7 million patients per year presenting to emergency departments (ED) for traumatic injury, about 10% of these traumas primarily involve the GU system, and another 10–15% of patients with abdominal trauma will have GU injuries as well.1 GU trauma patients are predominantly young (80% less than the age of 45 years) and male (85% of all patients).2 Delays or missed diagnosis of GU trauma can result in increased morbidity and mortality due to preventable complications with long term consequences.3



Overview




  • Injury can be a result of penetrating or blunt trauma involving the chest, abdomen, and/or back.




    • Non-iatrogenic blunt trauma mechanisms, most commonly motor vehicle collisions, account for approximately 90% of injuries to the GU system.4



    • GU injuries in sports-related events most commonly involve the external genitalia.5



    • Only 1–3% of penetrating trauma involves the GU system.2




  • The most commonly injured urological organ is the kidney, followed by the testicles and bladder.2



  • Delays in diagnosis are common as GU injuries rarely occur in isolation.




    • 20–25% of all bladder and urethral injuries associated with pelvic fractures are initially missed.2




Signs and Symptoms




  • For any trauma, make sure to undress the patient to evaluate for subtle signs such as perineal ecchymosis that may indicate deeper injuries.



  • Though more often absent, Grey-Turner’s sign, abdominal or flank tenderness or pain, hematuria, and potentially a palpable mass can suggest GU trauma.




    • Hematuria is absent in 5–36% of patients.1



    • Even severe injuries such as renal artery injury or ureteropelvic disruption can present without hematuria.




  • Suspect bladder injury in the patient who is oliguric despite adequate fluid replacement and in patients who are unable to void but are not hypovolemic.



  • Though classic examination findings for ureteral and bladder injuries include blood at the meatus, perineal or scrotal hematoma, and high riding prostate, these findings are uncommon.



  • A history of pre-existing renal structural or functional disorders is important to note, which increases the risk for injury and also increases trauma-associated acute kidney injury from insults such as hypotension, rhabdomyolysis, and contrast-induced nephropathy.6



  • Pre-existing urologic pathology that alter bladder sensation, such as neurogenic bladder disorder, places patients at greater risk of missed injury.2



Diagnostic Studies




  • Baseline renal function: Initial creatinine performed after traumatic injury likely reflects pre-existing renal insufficiency rather than impact of renal or GU injury.2




    • Rising urea and creatinine in a patient with isolated GU trauma can suggest renal impairment due to traumatic injury, reabsorption of extravasated urine, or contrast induced nephropathy following diagnostic imaging.




  • Urinalysis should be performed on all abdominal trauma patients.




    • The first spontaneously voided sample of urine is essential to identify hematuria, as this has the highest sensitivity before fluid administration or diuresis obscures its presence.2



    • Hematuria can be gross (i.e. visible) or microscopic (more than five red blood cells per high-power field).7



    • Gross hematuria is more suggestive of a bladder or ureter injury.



    • Generally speaking, the greater the degree of hematuria, the greater the risk of significant intra-abdominal injury.




      1. 50% of patients with macroscopic hematuria in blunt trauma have renal injuries, and a further 15% have injuries to other intra-abdominal organs.2



      2. No hematuria is seen in 5% of renal injuries or 20% of renovascular injuries.8



      3. There is no correlation between amount or presence of hematuria and degree of injury.




    • Management of hematuria depends on the mechanism of injury and the clinical picture (Figure 16.1). The EAST guidelines make suggestions for management of traumatic hematuria.9




      1. Penetrating trauma to the abdomen requires surgical exploration.



      2. Asymptomatic patients with microscopic hematuria in blunt trauma require no further imaging and can be followed up with repeat urinalysis in 1 week with the primary care provider.



      3. In blunt trauma patients with gross hematuria or who are unstable (defined as systolic blood pressure less than 90 mmHg) with microscopic hematuria, a computed tomography (CT) is needed to evaluate for urologic damage.



      4. CT is indicated in patients with a significant mechanism of injury including rapid deceleration, significant injury to the flank, rib fracture, significant flank ecchymosis, penetrating injury of abdomen, flank, or lower chest.





  • Bedside ultrasound is recommended in all abdominal trauma patients.2




    • Ultrasound can identify intraperitoneal fluid but has minimal utility in diagnosing parenchymal trauma or retroperitoneal bleeding.



    • A focused assessment with sonography in trauma (FAST) exam can be performed at the bedside to evaluate for intraperitoneal bleed (Figure 16.2).



    • A dedicated bladder view in a patient with or without urinary catheter in place can help evaluate for urinary retention (Figure 16.3).



    • US can also help detect penile fracture or evaluate for testicular injury and viability and vulnerability of the tissue.




  • CT of the abdomen and pelvis with intravenous (IV) contrast is the gold standard in assessing renal and GU trauma.2




    • More sensitive and specific than intravenous pyelogram, ultrasound, or angiography.2



    • Better detects, localizes, and characterizes the nature of injuries.



    • Useful for evaluating other injuries as well as detecting injuries in patients with pre-existing urological structural abnormalities.



    • Findings that suggest major renal injury include hematoma, urinary extravasation, and lack of contrast enhancement of the renal parenchyma.



    • Indicated in patients with:2




      1. Blunt abdominal trauma and gross hematuria.



      2. Blunt abdominal trauma with 5–30 RBCs/HPF when there is hypotension or other signs of shock, or injuries that would require it (such as a positive FAST examination).



      3. Blunt trauma with injuries known to be associated with renal injury such as rapid deceleration, direct contusion to the flank, flank ecchymosis, or fracture of the lower ribs or thoracolumbar spine, regardless of hematuria.



      4. Penetrating trauma to upper abdomen or lower thorax regardless of hematuria.




    • Conventional CT imaging is obtained before contrast is excreted in the urine and can miss 80% of ureteral injury from blunt trauma.2




      1. 10-minute-delayed CT images of the pelvis should be obtained in the setting of high grade renal injury, ureteropelvic junction injury, or any concern for ureteral injury.10



      2. Findings include extravasation, periureteral urinoma, or a lack of contrast distal to the suspected ureteral injury.





  • CT Cystography




    • Performed by draining the bladder via a Foley catheter or suprapubic catheter, instilling 350 cc of diluted, sterile CT contrast (made with 30 cc of contrast in a 500 cc bag of warmed normal saline) into the bladder by gravity, clamping the catheter, and obtaining CT images of the pelvis.10



    • Should be added to CT abdomen/pelvis with IV contrast when the patient has:2




      1. Gross hematuria



      2. Pelvic free fluid without another explanation other than bladder injury



      3. Any pelvic fracture other than acetabular fractures



      4. Isolated microhematuria with physician concern



      5. Difficulty voiding or suprapubic pain and any hematuria



      6. Penetrating injuries to the buttock, pelvis, or lower abdomen with any hematuria




    • Sensitivity for detecting bladder injuries is 78–100%.11




  • CT Angiography: Generally performed perioperatively to localize acute arterial hemorrhage in preparation for surgical repair and/or embolization.



  • Retrograde Urethrogram (RUG)




    • Should be performed prior to blind insertion of urinary catheter if there is concern for urethral injury, pelvic fracture, the inability to urinate, or significant pelvic swelling or ecchymosis.12



    • Performed by gently stretching the penis over the thigh at an oblique angle to radiographically visualize the entire urethra, with x-ray obtained as a scout for comparison before contrast is instilled. Contrast is then instilled into the urethral meatus. Abdominal radiograph is then performed to evaluate for contrast extravasation along the course of the urethra which indicates urethral disruption.2



    • This can interfere with contrast used in CT with IV contrast and should be performed in a delayed fashion.



    • A pericatheter RUG can be performed if a urinary catheter has already been placed and urethral injury is suspected.2




  • Intravenous Pyelogram (IVP): This is an option if CT is unavailable or imaging needs to be carried out in the operating room, though it is less sensitive than CTs and cannot visualize non-urologic injuries.



  • Magnetic Resonance Imaging (MRI): While there are some reports citing the use of MRI in evaluation of GU trauma, MRI is never an appropriate imaging study for the unstable patient. Given the more readily available imaging modalities discussed above, its utility in the ED is very limited.2





Figure 16.1 Management of hematuria based on EAST guidelines





Figure 16.2 Positive FAST exam showing free fluid in the pelvis





Figure 16.3 Despite the presence of a Foley catheter, this ultrasound of the bladder shows urinary retention



Kidney



Anatomy





  • The kidneys and ureters are protected by adjacent anatomic structures but are suspended by the renal pedicle without other firm attachments.




  • Damage to these organs usually is secondary to direct flank trauma or rapid deceleration injury: high speed motor vehicle crash, fall from significant height, etc.




    • The kidneys are susceptible to contusions, lacerations (renal fractures), hematomas, avulsions of the renal vasculature, renal artery thrombosis, etc.



    • Fracture of the lower posterior ribs, lower thoracic, or lumbar vertebrae can be associated with renal or urethral injuries.



    • 250,000 traumatic renal injuries occur annually worldwide.2



    • The kidneys are often injured in patients with multitrauma and seen in 8–10% of patients hospitalized for abdominal trauma.2




  • Children are at higher risk of blunt renal injury than adults.13




    • Pediatric kidneys are more mobile, larger relative to body size, not as well protected by fat, and more anatomically forward.13




  • Pre-existing structural urologic pathology such as hydronephrosis, tumors, cysts, strictures, or solitary kidney is highly associated with renal injury after even minor trauma and requires more intensive evaluation. 14




Evaluation




  • Includes urinalysis, CT abdomen with IV contrast, intravenous pyelogram, and renal angiography if indicated (Figure 16.4).



  • Grading of renal injury is important with regard to management and is defined by the American Association for the Surgery of Trauma (Table 16.1).8


Figure 16.4



(A) CT scan of patient with blunt renal artery injury (no contrast uptake). There is isolated renal artery thrombosis without any parenchymal injury (left). The operative specimen (right) shows a clot in the renal artery.





(B) Patients with renal artery thrombosis, associated parenchymal injuries (left), and extensive perirenal hematomas (right). These cases are less likely to be managed successfully with endovascular stenting


(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)



Table 16.1 Renal injury classification

























Grade Injury
Grade I


  • Contusion with microscopic or gross hematuria with normal urologic studies



  • Nonexpanding subcapsular hematoma without parenchymal laceration

Grade II


  • Nonexpanding hematoma confined to the renal retroperitoneum



  • Laceration less than 1 cm parenchymal depth of the renal cortex without urinary extravasation

Grade III


  • Laceration more than 1 cm parenchymal depth of the renal cortex without collecting system rupture or urinary extravasation

Grade IV


  • Laceration extending through the renal cortex, medulla, and collecting system



  • Segmental renal artery or vein injury with contained hemorrhage

Grade V


  • Completely shattered kidney



  • Avulsion of renal hilum that devascularizes the kidney



Management




  • Initial management includes fluid resuscitation, bed rest, and serial monitoring of vitals and hemoglobin. Urologic consult should be obtained.



  • Most renal injuries (Grades I–III and most grade IV injuries) can be managed conservatively and tend to heal spontaneously.



  • Surgical repair is required in the setting of urine extravasation, ongoing bleeding, hemodynamic instability, or suspicion of renovascular injury.15



  • Renal pedicle injury, most commonly due to deceleration injury involving violent sheering of the kidney on its vascular pedicle, can result in life threatening hemorrhage and renal ischemia.




    • This can lead to thrombosis or complete detachment at the pedicle.



    • Early surgical repair is needed to rescue the kidney, although nephrectomy may result.




  • Interventional radiology can also be used to embolize bleeding vessels or stent dissected renal arteries.2



  • Higher grade renal injuries with anticipated nonoperative management require admission for bed rest, observation, serial hematocrit testing, monitoring of urine output and degree of hematuria, and potentially serial CT scans.



Complications


Complications include uncontrolled hemorrhage, delayed abdominal findings due to retroperitoneal position, thrombosis of renal vein or artery, urine extravasation, infection, abscesses, urinoma formation, secondary hemorrhage, hypertension, “Page” kidney (scarring leading to hypertension), hydronephrosis, calculi, and chronic pyelonephritis.2




  • Damage to renal vasculature can result in necrosis if left untreated.



  • Delayed onset of gross hematuria after injury increases the likelihood for a rare potentially life-threatening complication of renal artery pseudoaneurysm.



Ureter



Anatomy




  • Ureters are hollow organs that are highly mobile within the retroperitoneal fat and protected by the psoas muscles. As such, they are rarely injured in blunt trauma.1



  • Represents less than 1% of GU injuries.15



  • When injured, they are susceptible to contusion, laceration, transection, and avulsion.



  • 95% of ureteral injury is due to gunshot wounds.15



  • The ureter is injured in approximately 5% of penetrating wounds to the abdomen.2, 7



  • Penetrating trauma involving the ureter often involves simultaneous hollow viscus and vasculature injuries.



  • Ureteral injuries due to blunt trauma are seen in conjunction with lumbosacral spine injuries and pelvic fractures, reflecting the extreme force needed to stretch or rupture the walls of the tubular ureter.16



Evaluation




  • Injury should be expected in the patient with unexplained rise in BUN and creatinine or presence of urinoma on imaging (often delayed).



  • Diagnosis requires delayed CT scan images 5–8 minutes after administration of contrast.15



Management


Treatment involves operative repair, placement of a ureteral stent, or percutaneous nephrostomy tube placement.2



Complications


Complications include urine extravasation with urinoma formation, infection, secondary hemorrhage, and stricture formation leading to hydronephrosis.



Bladder



Anatomy




  • Bladder injuries can involve mural contusions, hematoma, laceration, and ruptures.




    • Typically associated with pelvic fractures or penetrating trauma close to the bladder.




  • The amount of urine in the bladder at the time of injury is directly related to risk of rupture, as injury often occurs with a distended bladder full of urine.




    • Pregnant women and intoxicated patients (with full bladders) are at higher risk.




  • Children are more susceptible to bladder injury as their bladders are an intra-abdominal organ and, thus, less protected by the pelvis.13



  • Patients can present with lower abdominal pain, hematuria, palpable fullness, azotemia, inability to void, or concomitant pelvic fracture.




    • Only 2% of bladder ruptures are seen in isolation. Assessment should focus on other concomitant injuries.2



    • Approximately 80% of bladder injuries occur with pelvic fractures.




  • Ruptures are classified as intraperitoneal, extraperitoneal, or combined (Table 16.2).16


Jan 10, 2021 | Posted by in EMERGENCY MEDICINE | Comments Off on Chapter 16 – Genitourinary Trauma
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