Basics
Description
- Kidneys are located in the retroperitoneal space and are surrounded by adipose tissue and loose areolar connective tissue.
- Kidneys lie along the lower 2 thoracic vertebrae and 1st 4 lumbar vertebrae.
- Left kidney is positioned slightly higher than the right.
- Kidneys are not fixed:
- Shift with the diaphragm and are supported by the renal arteries, veins, and adipose tissue to the renal (Gerota) fascia
Etiology
- Most common of all urologic injuries
- Occurs in ’ Ό8 " 10% of all abdominal trauma
- Blunt renal trauma accounts for 80 " 85% of all renal injuries and is 5 times more common than penetrating injury:
- Mechanisms include motor vehicle accidents, falls, domestic violence, and contact sports.
- Pathophysiology includes rapid deceleration and displacement mechanisms.
- ’ Ό20% of cases are associated with intraperitoneal injury.
- Mechanisms responsible for significant renal injury almost never affect the kidney alone:
- Most often disrupt and injure other vital organs that can be responsible for patient mortality
- Renal injuries are graded by type and severity of injury (Association for the Surgery of Trauma [AAST] criteria)
- Grade I
- Contusion: Microscopic or gross hematuria, urologic studies normal
- Hematoma: Subcapsular, nonexpanding without parenchymal laceration
- Grade II:
- Hematoma: Nonexpanding, perirenal hematoma confined to retroperitoneum
- Laceration: <1 cm parenchymal depth of renal cortex without urinary extravasation
- Grade III
- Laceration: >1 cm parenchymal depth of renal cortex without collecting system rupture or urinary extravasation
- Grade IV:
- Laceration: Parenchymal laceration extending through renal cortex, medulla, and collecting system
- Vascular: Main renal artery or vein injury with contained hemorrhage
- Grade V:
- Laceration: Completely shattered kidney
- Vascular: Avulsion of renal hilum, devascularizing the kidney
- The kidney is the organ most commonly damaged by blunt abdominal trauma.
- Contributing factors:
- Relatively larger size of kidneys compared with adults
- 10th and 11th ribs are not completely ossified until the 3rd decade of life.
- Significant abdominal injury occurs in about 5% of nonaccidental trauma cases but is the 2nd most common cause of death after head injury.
Diagnosis
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
- 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 ’ Ό50% 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
Treatment
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 patients 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.
- ’ Ό80 " 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.
Follow-Up
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
Additional Reading
- Broghammer JA, Fisher MB, Santucci RA. Conservative management of renal trauma: A review. Urology. 2007;70(4):623 " 629.
- Mee SL, McAninch JW, Robinson AL, et al. Radiographic assessment of renal trauma: A 10-year prospective study of patient selection. J Urol. 1989;141:1095 " 1098.
- Santucci RA, Wessells H, Bartsch G, et al. Evaluation and management of renal injuries: Consensus statement of the renal trauma subcommittee. BJU Int. 2004;93(7):937 " 954.
- Shoobridge JJ, Corcoran NM, Martin KA, et al. Contemporary management of renal trauma. Rev Urol. 2011;13(2):65 " 72.
- Tinkoff G, Esposito TJ, Reed J, et al. American Association for the Surgery of Trauma Organ Injury Scale I: Spleen, liver, and kidney, validation based on the National Trauma Data Bank. J Am Coll Surg. 2008;207(5):646 " 655.
Codes
ICD9
- 866.00 Injury to kidney without mention of open wound into cavity, unspecified injury
- 866.01 Injury to kidney without mention of open wound into cavity, hematoma without rupture of capsule
- 866.02 Injury to kidney without mention of open wound into cavity, laceration
- 866.03 Injury to kidney without mention of open wound into cavity, complete disruption of kidney parenchyma
- 866.0 Injury to kidney without mention of open wound into cavity
- 866.10 Injury to kidney with open wound into cavity, unspecified injury
- 866.11 Injury to kidney with open wound into cavity, hematoma without rupture of capsule
- 866.12 Injury to kidney with open wound into cavity, laceration
- 866.13 Injury to kidney with open wound into cavity, complete disruption of kidney parenchyma
- 866.1 Injury to kidney with open wound into cavity
ICD10
- S37.009A Unspecified injury of unspecified kidney, initial encounter
- S37.019A Minor contusion of unspecified kidney, initial encounter
- S37.049A Minor laceration of unspecified kidney, initial encounter
- S37.069A Major laceration of unspecified kidney, initial encounter
- S37.001A Unspecified injury of right kidney, initial encounter
- S37.002A Unspecified injury of left kidney, initial encounter
- S37.011A Minor contusion of right kidney, initial encounter
- S37.012A Minor contusion of left kidney, initial encounter
- S37.021A Major contusion of right kidney, initial encounter
- S37.022A Major contusion of left kidney, initial encounter
- S37.029A Major contusion of unspecified kidney, initial encounter
- S37.031A Laceration of right kidney, unspecified degree, init encntr
- S37.039A Laceration of unsp kidney, unspecified degree, init encntr
- S37.041A Minor laceration of right kidney, initial encounter
- S37.042A Minor laceration of left kidney, initial encounter
- S37.051A Moderate laceration of right kidney, initial encounter
- S37.052A Moderate laceration of left kidney, initial encounter
- S37.059A Moderate laceration of unspecified kidney, initial encounter
- S37.061A Major laceration of right kidney, initial encounter
- S37.062A Major laceration of left kidney, initial encounter
- S37.091A Other injury of right kidney, initial encounter
- S37.092A Other injury of left kidney, initial encounter
- S37.099A Other injury of unspecified kidney, initial encounter
SNOMED
- 40095003 injury of kidney (disorder)
- 70092007 Contusion of kidney (disorder)
- 262893009 Laceration of kidney (disorder)
- 283905005 Avulsion of kidney (disorder)
- 20341008 Injury of kidney without open wound into abdominal cavity (disorder)
- 210197003 Closed injury of kidney (disorder)
- 210811000 Renal blood vessel injury (disorder)
- 61474001 Injury of kidney with open wound into abdominal cavity (disorder)