SIGNS AND SYMPTOMS 
History
- Mechanism of injury and kinematics are important factors.
- Majority of renal injuries are associated with injury of other abdominal organs.
- In blunt trauma, note the type and direction (horizontal or vertical) of any deceleration or compressive forces.
- In penetrating trauma, note the characteristic of the weapon (type and caliber), distance from the weapon, or the type and length of knife or impaling object:
- Injuries result from a combination of kinetic energy and shear forces of penetrating object.
Physical Exam
- Hematuria is the best indicator of traumatic urinary system injury:
- Severity of renal trauma does not correlate with the degree of hematuria.
- Absence of hematuria does not exclude renal injury
- Microscopic hematuria with a systolic BP < 90 mm Hg
- Flank mass or ecchymosis
- Tenderness in the flank, abdomen, or back
- Fracture of the inferior ribs or spinal transverse processes
- Nausea and vomiting
ESSENTIAL WORKUP
- In 1989, Mee et al. published the hallmark article (10-yr prospective study) that established guidelines for the evaluation and treatment of blunt renal trauma:
- Major renal lacerations represent significant reparable renal injuries.
- Adult patients at risk for having sustained major lacerations:
- Gross hematuria, or
- Microhematuria (≥3–5 RBCs/HPF) with shock (systolic BP ≤90 mm Hg) in the field or on arrival in the ED, or
- History of sudden deceleration without hematuria or shock
- IV contrast-enhanced CT scan is the procedure of choice in identifying urologic injury.
- Guidelines are not applicable in cases of penetrating renal trauma or in children.
- Adults with blunt renal trauma and gross hematuria, or microhematuria in the presence of shock, require renal imaging for further evaluation of renal injury.
- In adults with penetrating renal trauma, significant injuries to the kidney and ureter can occur without hematuria:
- Location of penetrating wound in relation to urinary tract is the most important factor in deciding need for radiographic imaging.
- Penetrating injuries with any degree of hematuria should be imaged.
- Important to rule out coexisting injuries
DIAGNOSIS TESTS & INTERPRETATION
Lab
- Urinalysis: Gross hematuria or > 50 RBCs/HPF in adults and > 20 RBC/HPF in children is suggestive of renal injury.
- Baseline lab values including hematocrit and BUN/creatinine should be obtained.
Imaging
- Plain abdominal films:
- May show fractured inferior ribs or transverse processes, a unilateral enlarged kidney shadow, or obscuring of the psoas margin
- IV pyelogram (IVP):
- Bolus infusion IVP with nephrotomography study of choice in institutions without 24-hr availability of CT
- Rapid injection of 1.5–2 mL of contrast material per kilogram of body weight to a maximum or 150 mL after obtaining a preliminary kidney, ureter, and bladder image
- Postinfusion supine film is obtained followed by 1-, 2-, and 3-min supine films.
- Allows evaluation for renal viability and function
- Extravasation reflects injury to the collecting system.
- Nonvisualization of a kidney may indicate renal pedicle injury or parenchymal shattering.
- Abnormal findings are often nonspecific and require more definitive studies.
- Ultrasound:
- Role in evaluation of renal injury is controversial
- Routinely performed at bedside in trauma patients as part of focused assessment with sonography in trauma (FAST)
- May show size of perirenal hematoma and whether it is expanding or resolving
- Low sensitivity for identification of retroperitoneal free fluid
- Otherwise, exam is nonspecific and does not provide enough information
- CT scan:
- An IV contrast-enhanced helical CT scan is the diagnostic procedure of choice.
- Superior anatomic detail and diagnostic accuracy of 98% for renal injury
- Sensitive indicator of minor extravasation, parenchymal laceration, vascular injury, and nonrenal injuries
Pediatric Considerations
- Major blunt renal trauma can occur in the absence of gross hematuria or shock (as children have a high catecholamine output after trauma, which maintains BP until ~50% of blood volume has been lost).
- Meta-analysis has defined 50 RBC/HPF as the microscopic quantity below which imaging can be omitted and no significant injuries missed.
- CT scan is the imaging modality of choice.
Diagnostic Procedures/Surgery
- Renal parenchymal injury
- Renal vascular injury
- Ureteral injury
- Bladder or urethral injury
[Outline]
PRE-HOSPITAL
- Obtain details of injury from pre-hospital providers.
- IV access
- Penetrating wounds or evisceration should be covered with sterile dressings.
INITIAL STABILIZATION/THERAPY
- Airway management (including C-spine immobilization)
- Standard Advanced Trauma Life Support (ATLS) resuscitation measures:
- Adequate IV access, including central lines and cutdowns, as dictated by the patient's hemodynamic status
- Fluid resuscitation, initially with 2 L of crystalloid (NS or lactated Ringer solution), followed by blood products as needed
- Rule out potential life-threatening injuries 1st.
ED TREATMENT/PROCEDURES
- Immediate laparotomy in the acutely injured patient who is hemodynamically unstable with presumed hemoperitoneum and renal injury
- Significant injuries (grades II–V) are found in only 5.4% of renal trauma cases.
- 98% of blunt renal injuries can be managed nonoperatively.
- ~80–90% of renal injuries have major associated organ injury that can affect the choice of renal injury management.
- Angiography and selective renal embolization has an increasing role and is an alternative treatment to laparotomy in patients not requiring immediate surgery.
- Penetrating renal trauma:
- Previously exploratory laparotomy was recommended for all patients with penetrating renal injuries.
- Nonoperative management has become more accepted for grades I–III with penetrating renal injuries in the absence of associated intra-abdominal injury or hemodynamic instability
- Blunt renal trauma:
- Isolated renal injury without significant associated injuries occurs more commonly from blunt trauma, and in most circumstances, can be managed nonoperatively.
- Classes I and II: Contusions and minor lacerations with stable vital signs and urographically normal renal function can be managed nonoperatively.
- Class III: Renal lacerations with urinary extravasation:
- Controversy between operative vs. nonoperative management
- Management should be based on degree of injury using CT scanning.
- Classes IV and V: Shattered kidney or renal pedicle injuries and hemodynamically unstable patients require emergent laparotomy.
- All ureteral injuries require operative repair.
[Outline]
DISPOSITION
Admission Criteria
Patients with significant renal injury require hospitalization for definitive laparotomy or observation.
Discharge Criteria
- Adult trauma patients without hematuria, shock, or no renal injury confirmed radiographically
- Adult blunt trauma patient with microhematuria (≥3–5 RBCs/HPF) but no shock (systolic BP ≤90 mm Hg)
- Pediatric blunt trauma patient with ≤50 RBC/HPF and no other coexisting major organ injuries
Issues for Referral
- Outpatient referral to urologist should be made for microhematuria to ensure that it does not represent a more serious underlying condition.
- Urinoma formation is the most common complication (1–7%) of patients with renal trauma:
- Urinary extravasation resolves spontaneously in 76–87% of cases