Upper Genitourinary (Kidney, Ureter) Trauma

Updated: Jan 10, 2023
Author: Sunny Mei-Chun Wang, MD, FACEP; Chief Editor: Trevor John Mills, MD, MPH 

Overview

Practice Essentials

Because trauma is a multisystem disease, multiple injuries may be present in the trauma patient. The kidneys, the pelvocaliceal system, and the ureters constitute the upper GU tract. Adult kidneys are well protected by the rib cage and the vertebral column, but lateral forces can compress them between these structures, leading to injury. Sudden deceleration can cause avulsion injuries to the renal pedicle and the pelvocaliceal system. The most common causes of renal injury are blunt trauma and penetrating trauma.[1, 2, 3, 4]  Other injuries often take priority over injuries to the genitourinary (GU) system and may initially interfere with or postpone a complete urologic assessment. Coordinated efforts between various services caring for the patient are crucial to ensure comprehensive care, and evaluation of the injured patient with possible GU trauma should not differ from that of other trauma patients. The protocols of the Advanced Trauma Life Support (ATLS) program of the American College of Surgeons should be followed to provide total patient care.[5, 6, 7]  

(See the images below.)

Ruptured left kidney. Ruptured left kidney.
Contrast-filled urinoma. Contrast-filled urinoma.
Avulsed left renal artery with thrombosis. Avulsed left renal artery with thrombosis.

From 3 to 10% of patients with multiple trauma have GU involvement; 10-15% of trauma patients with abdominal injuries have GU involvement. Renal injuries constitute 45% of all GU injuries; ureteral injuries account for 6%.

Mortality from upper GU tract injuries is attributed primarily to other associated injuries; morbidity is 26%. Trauma is the leading cause of death among persons aged 1-40 years and is the third-ranked cause of mortality in all age groups.

According to the National Trauma Data Bank, most renal trauma in children is low grade, is blunt in nature, and occurs in children older than 5 years. Although most pediatric patients are treated conservatively, the rate of nephrectomy has been found to be 3 times higher at adult hospitals than at pediatric centers. Of reported injuries, 79% were found to be grade I, II, or III, and penetrating injuries accounted for less than 10% of all pediatric renal injuries.[8]

Only 6% of patients with GU trauma have ureteral injuries, probably due to the small size and mobility of the ureter, along with the protection provided by the psoas muscle posteriorly, the abdominal viscera anteriorly, and the vertebral column medially.

Findings

Renal trauma includes hemorrhage, urinoma, loss of function of kidney, pseudoaneurysm formation, arteriovenous fistula (rare), renal hypertension, and obstruction of collecting system and renal artery aneurysm (pseudo). Ureteral injury includes urinary extravasation, urinoma, infection and stricture formation leading to hydronephrosis.

Flank ecchymosis or mass indicates a retroperitoneal process but is not specific to renal injuries and rarely occurs acutely. The most important indicator of renal trauma is gross or microscopic hematuria. Absence of hematuria, although rare, does not exclude renal injury. Hematuria is absent in 5% of patients.

The presence of abdominal, visceral, solid organ, or vascular injury may indicate concomitant renal injury, as these injuries coexist with renal injury in 34% of patients with blunt trauma and in up to 80% of patients with penetrating trauma.

In suspected ureteral injury, physical examination is of minimal use except in diagnosis of associated injuries.

A rectal examination should be performed to help establish the presence or absence of a urethral injury before Foley catheter insertion. The examiner should look for a high-riding prostate, a rectal tear, a bony abnormality, or frank blood.

Computed tomography (CT) is preferred over intravenous pyelography (IVP) in patients with renal injuries because CT provides better anatomic and functional details, it has higher sensitivity, and it is associated with improved time to results. Multidetector CT scanners can provide even greater image resolution, along with the possibility of CT angiography of the kidneys.[9]

AAST renal and ureter injury scales

Grade of renal injury (based on CT findings) is depicted in the scale developed by the American Association for the Surgery of Trauma (AAST) (see below)[10, 11] :

  • Grade I: Subcapsular hematoma and/or parenchymal contusion without laceration.
  • Grade II: Perirenal hematoma confined to Gerota fascia; renal parenchymal laceration ≤1 cm depth without urinary extravasation.
  • Grade III: Renal parenchymal laceration >1 cm depth without collecting system rupture or urinary extravasation; any injury in the presence of a kidney vascular injury or active bleeding contained within Gerota fascia.
  • Grade IV: Parenchymal laceration extending into urinary collecting system with urinary extravasation; renal pelvis laceration and/or complete ureteropelvic disruption; segmental renal vein or artery injury; active bleeding beyond Gerota fascia into the retroperitoneum or peritoneum; segmental or complete kidney infarction(s) due to vessel thrombosis without active bleeding.
  • Grade V: Main renal artery or vein laceration or avulsion of hilum; devascularized kidney with active bleeding; shattered kidney with loss of identifiable parenchymal renal anatomy.

The AAST ureter injury scale is as follows[12, 11] :

  • Grade I: Hematoma - Contusion or hematoma without devascularization.
  • Grade II: Laceration - < 50% transection.
  • Grade III: Laceration - ≥50% transection.
  • Grade IV: Laceration - Complete transection with < 2cm devascularization.
  • Grade V: Laceration - Avulsion with >2cm of devascularization.

Treatment

Grade I, II, and III injuries are treated conservatively. Vital signs, hematocrit level, and progression of hematuria should be monitored. In most cases, patients heal without any intervention, but in rare cases, radiologic selective embolization is needed to control hematuria. A 60% success rate has been reported with grade IV injuries, with expectant treatment of extravasation if ureteral outflow has not been affected.

 

Presentation

History

In blunt trauma, history should include the time and mechanism of injury, the position of the patient, the speed of the vehicle (if a vehicle is involved), and the use of restraints.

In penetrating trauma, knowing the size of the stabbing weapon or the caliber of the gun and the distance from which it was discharged aids assessment.

Paramedics should be questioned as to the condition of the patient immediately after injury occurred and during transport to the hospital.

In patients with GU trauma, symptoms are nonspecific and may be masked by or attributed to other injuries.

Renal injuries most commonly result from motor vehicle accidents (MVAs). Renal injuries occur in 3% of patients hospitalized with trauma and in 10% of those with abdominal trauma. Most renal injuries (80%) are minor and do not require surgical intervention.

Renal injury should be suspected when fractures of lower ribs and/or spinal processes are observed and/or when a history of sudden deceleration or significant lateral force on the patient exists. In penetrating trauma, the trajectory of the bullet or the penetrating object may reveal the possibility of renal injury.

Iatrogenic ureteral injuries are much more frequent than violent ones. A high incidence of associated organ injuries with ureteral injuries exists (90% in gunshot wounds, 60% in stabbings). Diagnosis of ureteral injury depends mainly on clinical suspicion. History and physical examination are unreliable and often are not sensitive.

Iatrogenic injury to the ureter can be a devastating complication of modern surgery. Most often, such injuries to the ureters occur during gynecologic, colorectal, or vascular pelvic surgery.[13]

Causes

The most common cause of renal injury is blunt trauma, followed by penetrating trauma.[1] Motor vehicle accidents and gunshot wounds account for 80% of renal injuries. Conversely, the etiology of ureteral trauma is most often iatrogenic (82%). In noniatrogenic cases of ureteral injury, penetrating trauma accounts for 90% (missile injury in 90%, stabbing injury in 10%), with a blunt avulsing-type mechanism causing the remaining 10% of injuries.

Blunt trauma includes the following:

  • MVAs

  • Motorcycle accidents

  • Falls from high elevations

  • Bicycle accidents

  • Assaults with blunt weapons

Penetrating trauma includes the following:

  • Missile injuries: One should differentiate between low- and high-velocity missiles.

  • Shotgun wounds: Close-range injuries are equivalent to high-velocity injuries.

  • Stabbings

  • Impalements

Iatrogenic trauma is also reported.

 

DDx

Differential Diagnoses

Workup
 

Workup

Laboratory Studies

Lab studies include the following:

  • Complete blood count (CBC) to obtain hematocrit level and platelet count

  • Prothrombin time (PT) and activated partial thromboplastin time (aPTT) to check for coagulopathy (may be unnecessary in young, otherwise healthy patients)

  • BUN and serum creatinine: Elevation of BUN without elevation in creatinine indicates urine reabsorption

  • Urinalysis to diagnose hematuria

  • Blood type and crossmatch

Imaging Studies

Use of diagnostic imaging techniques is crucial in functional and anatomic assessment of the injured and uninjured kidney.

Urologic imaging should be performed only when indicated, as persistent low yield occurs with imaging of patients with microscopic hematuria, patients with no associated injuries, and patients who are hemodynamically stable.

Indications for imaging include the following:

  • Gross hematuria

  • Microscopic hematuria with hemodynamic instability

  • Persistent microscopic hematuria (serial urine analysis)

  • Hemodynamic instability with history of significant deceleration mechanism

CT scan

CT scan is preferred over intravenous pyelography in renal injuries because of its superiority in providing anatomic and functional details, its higher sensitivity, and improved time to results with the advent of spiral CT techniques. Multidetector CT scanners offer even greater image resolution and enable CT angiography of the kidneys.[9, 14, 15, 16]

Grade of renal injury (based on CT findings) is depicted in the scale developed by the American Association for the Surgery of Trauma (see below)[10] :

  • Grade I: Subcapsular hematoma and/or parenchymal contusion without laceration.
  • Grade II: Perirenal hematoma confined to Gerota fascia; renal parenchymal laceration ≤1 cm depth without urinary extravasation.
  • Grade III: Renal parenchymal laceration >1 cm depth without collecting system rupture or urinary extravasation; any injury in the presence of a kidney vascular injury or active bleeding contained within Gerota fascia.
  • Grade IV: Parenchymal laceration extending into urinary collecting system with urinary extravasation; renal pelvis laceration and/or complete ureteropelvic disruption; segmental renal vein or artery injury; active bleeding beyond Gerota fascia into the retroperitoneum or peritoneum; segmental or complete kidney infarction(s) due to vessel thrombosis without active bleeding.
  • Grade V: Main renal artery or vein laceration or avulsion of hilum; devascularized kidney with active bleeding; shattered kidney with loss of identifiable parenchymal renal anatomy.

CT scanning allows visualization of the rest of the abdomen for detection of urinomas. Microscopic hematuria without hemodynamic instability or a significant mechanism is not an indication for CT scan in patients with blunt trauma. CT scan should be performed in stable patients only if there is a history of hypotension; gross hematuria; or penetrating abdominal, flank, or back injury. Renal pedicle thrombosis may present without hematuria, but associated injuries or findings usually mandate CT scan or laparotomy.

When collecting system injuries are assessed, many may not be detected on initial CT, which suggests the need for repeat imaging in patients with large perinephric hematomas.[17]

(See the image below.)

CT scan of abdomen and pelvis showing a urinoma. CT scan of abdomen and pelvis showing a urinoma.

Intravenous pyelography

IVP provides information about the function of both kidneys; when performed with a double dose, it is the preferred test in suspected ureteral injuries. In renal injuries, CT scanning is preferred because of the relatively poor sensitivity of IVP.

If CT scan is not readily available and renal imaging is required, IVP is a good imaging study to perform as a first-line modality. CT scan or laparotomy should follow an abnormal IVP finding.

Renal arteriography

Renal arteriography should be used when therapeutic embolization is needed and when regional blood flow to the affected kidney must be determined when exploration is being considered.[18]

Transcatheter arterial embolization (TAE) has proved to be an alternative therapeutic modality for blunt renal injury in children who have contrast medium extravasations in the kidney on angiography.[19]

Ultrasonography

Ultrasonography is inferior to CT in anatomic detail and sensitivity. It may be helpful in follow-up care of patients with renal injuries and for detection of urinomas.[20]  Ultrasonography may also be useful in the acute setting of abdominal trauma as part of focused abdominal sonography in trauma (FAST) examination of the injured patient for detection of perirenal hematomas and other injuries to the abdomen.

Other modalities

Radionuclide scan is not helpful in diagnosis of renal injury but is useful in follow-up treatment related to function of the injured kidney.

Retrograde ureterography is useful for diagnosing ureteral injury, especially in cases of missed injury. It is invasive and requires a cystoscopy suite.

(See the image below.)

Retrograde urethrogram showing a leak in the dista Retrograde urethrogram showing a leak in the distal right ureter with an element of obstruction.

 

 

Treatment

Emergency Department Care

Adherence to ATLS principles is necessary for proper care of the trauma patient.

  • Administer oxygen and provide ventilatory support if needed.

  • Resuscitate with crystalloids (lactated Ringer solution or isotonic sodium chloride solution) and blood (O-negative or type-specific blood if known) if indicated.

  • Treat life-threatening injuries (eg, tension pneumothorax, open pneumothorax, cardiac tamponade) emergently in the ED.

Assess capabilities of the ED to handle the patient with multiple injuries that include upper GU trauma; decide whether to transfer based on that assessment.

Treat life-threatening injuries prior to transfer; stabilize and resuscitate the patient.

The transferring physician is responsible for the decision to transfer, the choice of transfer modality, and selection of an accepting facility.

The receiving physician confirms the ability of the receiving institution to handle the patient's condition.

Institutional transfer protocol facilitates the process.

Patients with upper GU trauma benefit from transfer when the following conditions exist at the transferring center:

  • CT scan is not available.

  • No staff urologist is present.

  • Multiple injuries surpass the care that hospital resources can provide.

  • Specialized care required for patient injuries is unavailable.

Consultations include the following:

  • Trauma or general surgeon for management of associated abdominal injuries

  • Urologist for management of specific GU injuries

  • Other specialists as injuries dictate

Outpatient care depends upon associated injuries and the need for rehabilitation (eg, orthopedic injuries, neurologic injuries).

Follow-up CT scan is indicated in patients with renal injuries to assess the progress of healing; IVP is required as follow-up care for ureteral repairs.

Insert a Foley catheter only after urethral injury is excluded. Consider performing a suprapubic cystostomy in a percutaneous or open manner when a Foley catheter is contraindicated or when it cannot be inserted and urine output measurement or detection of hematuria is required.

Prehospital care

Advancement of prehospital care for trauma patients is one of the biggest leaps forward in trauma care. Principles do not change with different organ injuries.

Paramedics quickly assess the patient and mechanism of injury, with special attention to patency of ABCs.

  • Establish an airway if needed and/or administer oxygen.

  • Establish 2 large-bore IVs.

Cervical spine precautions (eg, hard collar, backboard) should be taken.

The patient should be quickly transported to the trauma center.

 

Medical Care

Grade of Injury

Management of renal injuries depends on the grade of the injury and is linked to management of associated injuries.[21, 22]  Grade of renal injury is best depicted in the scale developed by the American Association for the Surgery of Trauma (see below).[23, 24, 25]

Grades I, II, and III injuries should be treated conservatively. Vital signs, hematocrit level, and progression of hematuria should be monitored. Most patients heal without intervention. Rarely, radiologic selective embolization is needed to control hematuria that does not subside spontaneously.

In grade IV injuries, expectant treatment of extravasation has a 60% success rate if ureteral outflow is not impeded. Flow obstruction can be corrected with stenting. If urinary extravasation does not improve, percutaneous drainage should be performed. Vascular injury indicates surgical intervention for repair, provided warm ischemia time does not exceed 4 hours. Hemorrhage control also indicates surgical exploration.[26]

Most children with grade IV renal injuries are treated by a conservative approach with a high success rate, but some may require urologic intervention because of symptomatic urinomas. According to one study, the need for transfusion and the presence of specific image features on initial CT (eg, main laceration location in the anteromedial portion of kidney), intravascular contrast extravasation, and a large perinephric hematoma may serve as useful predictive factors for urologic intervention in grade IV pediatric blunt renal trauma patients who were initially treated by a conservative approach.[27]

In grade V injuries, completely shattered kidneys require excision for control of hemorrhage. Kidneys with pedicular avulsion do not require removal unless a laparotomy already is being performed for a different pathology. Avulsed kidneys do not result in late sequelae if left in situ. Revascularization of the kidney should be attempted only if warm ischemia time is less than 4 hours, as failure rates are extremely high when warm ischemia time is more than 4 hours. High rates of infection and hypertension occur in kidneys with failed revascularization. Exceptions should be made for patients with solitary kidneys and decreased renal capacity.[28]

Management of acute ureteral injury primarily involves repair. Debridement is performed until a healthy bleeding ureter is reached; repair is performed at this point by the surgeon. The type of repair depends on the level of ureter injury and the length of ureter lost to injury and debridement.[29]

Treatment of ureteropelvic junction injuries requires reimplantation of the ureter into the renal pelvis. Ureteroureteral or ureterovesicular anastomoses are used for distal injuries; bladder flaps may be required for a tension-free anastomosis. Transureteroureterostomy (anastomosis of the injured ureter to the contralateral ureter) has lost favor because of associated danger to the normal ureter. Management of missed ureteral injuries includes drainage of urinomas (preferably percutaneously) with a nephrostomy. Inflammation is allowed to subside (3-6 wk), then a definitive surgical repair is performed.

Most children with grade IV/V renal injury following blunt trauma can be managed nonoperatively. Management can be properly planned and executed based on clinical features, CT imaging, and staging of renal injuries.[30]

Grade I

Contusion - Microscopic or gross hematuria with normal urologic studies

Hematoma - Subcapsular, nonexpanding injury without parenchymal laceration

Grade II

Hematoma - Nonexpanding injury confined to the renal retroperitoneum

Laceration - Less than 1 cm parenchymal depth of renal cortex without urinary extravasation

Grade III

Laceration - More than 1 cm parenchymal depth of renal cortex without collecting system rupture or urinary extravasation

Grade IV

Laceration - Injury extending through renal cortex, medulla, and collecting system

Vascular injury - Main renal artery or vein injury with contained hemorrhage

Grade V

Laceration - Completely shattered kidney

Vascular injury - Avulsion of renal hilum that devascularizes the kidney

 

Medication

Medication Summary

Medications for patients with upper GU injuries relate to management of patients as critically injured rather than specifically to management of patients with GU injuries.

Antibiotics

Class Summary

Antibiotics may be used for prophylaxis of infections of the injured GU tract. Empiric antimicrobial therapy must be comprehensive, covering all likely pathogens in the clinical setting.

Ampicillin and sulbactam (Unasyn)

Drug combination of beta-lactamase inhibitor with ampicillin. Covers skin, enteric flora, and anaerobes. Not ideal for nosocomial pathogens.

Cefotetan (Cefotan)

Second-generation cephalosporin indicated for infections caused by susceptible gram-positive cocci and gram-negative rods.

Dosage and route of administration depend on condition of patient, severity of infection, and susceptibility of causative organism.

Analgesics

Class Summary

Pain control is essential to quality patient care. Analgesics ensure patient comfort, promote pulmonary toilet, and have sedating properties, which are beneficial for patients who have sustained trauma.

A review of opioid equivalents and conversions may be found in the following reference article:

 http://emedicine.medscape.com/article/2138678-overview

Fentanyl (Sublimaze, Abstral, Actiq, Duragesic, Fentora, Ionsys, Lazanda, Onsolis, Subsys)

A synthetic opioid that is 75-200 times more potent with a much shorter half-life than morphine sulfate. Has fewer hypotensive effects and is safer than morphine for patients with hyperactive airway disease because of minimal-to-no associated histamine release. By itself, it causes little cardiovascular compromise, although added benzodiazepines or other sedatives may result in decreased cardiac output and blood pressure.

Fentanyl is highly lipophilic and protein bound. Prolonged exposure leads to accumulation in fat and delays weaning.

Consider continuous infusion because of the short half-life of fentanyl.

Parenteral form is DOC for conscious sedation analgesia and is ideal for analgesic action of short duration during anesthesia and the immediate postoperative period.

Excellent choice for pain management and sedation with short duration (30-60 min) and easy to titrate. Easily and quickly reversed by naloxone.

After initial parenteral dose, subsequent parenteral doses should not be titrated more frequently than q3h or q6h.

Transdermal form is used only for chronic pain conditions in opioid-tolerant patients. When the transdermal dosage form is used, most patients are controlled by 72-h dosing intervals; however, some patients require dosing intervals of 48 h.

Easily and quickly reversed by naloxone.

Morphine sulfate (Astramorph, Duramorph, MS Contin, Avinza, Infumorph, Kadian, MorphaBond, Arymo ER)

DOC for analgesia because of reliable and predictable effects, its safety profile, and ease of reversibility with naloxone.

Various IV doses are used; commonly titrated until desired effect obtained.

Postoperatively, oral morphine sulfate extended-release formulations may be prescribed for severe pain, with immediate-release preparations used for breakthrough pain. Arymo ER is a morphine sulfate abuse-deterrent derivative.