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Renal Trauma

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Ovid: 5-Minute Sports Medicine Consult, The


Renal Trauma
Nick Carter
Basics
Description
  • Back or abdominal trauma due to collision with other players or equipment may result in injury to the kidney and its collecting system. Because signs and symptoms may initially be subtle, a high level of suspicion is warranted, especially if other commonly associated injuries such as splenic trauma, rib fractures, or vertebra fractures are present.
  • Synonym(s):
    • Nephroptosis: Floating kidney, mobile kidney
    • Renal trauma: Kidney trauma, nephric trauma
Epidemiology
  • 5–10% of renal trauma occurs in sports.
  • ∼8–10% of all blunt and penetrating injuries to the abdomen involve the kidney. The kidney is the most commonly injured organ in the urogenital system. Blunt trauma accounts for 80–90% of kidney injuries.
  • The most common blunt trauma mechanism is rapid deceleration, especially to the upper abdominal area.
  • Vascular injury of renal vessels has been reported in 1–3% of patients with blunt trauma. Venous injuries following blunt or penetrating trauma to the kidney can result in rapid and massive blood loss with relatively few symptoms.
  • Injuries to the renal pedicle can lead to life-threatening blood Loss. Fortunately, these injuries account for only 1–2% of all renal injuries.
  • Among children, 16–25% of renal trauma is sports-related. The majority of injuries involve boys 11–17 yrs of age. Of children with renal trauma, 8–22% have congenital anomalies.
Risk Factors
  • Multiple fractures and injuries to abdominal organs, the vascular system, chest, and head make kidney trauma more likely.
  • Ectopic placement of kidneys elsewhere in the abdomen may predispose to injury due to lack of protection usually afforded by the ribs.
  • Pre-existing renal anomalies have been shown to be associated with injury in 0.1–23% of adult cases and in 0.4–23% of pediatric cases.
Diagnosis
History
  • Flank pain and tenderness are usually present.
  • The athlete may complain of gross hematuria.
  • History of a collision or fall is described.
Physical Exam
  • Diffuse abdominal tenderness with or without hematuria is the most common sign and symptom of kidney trauma.
  • Associated injuries such as lower rib fractures, vertebral body fractures, and flank trauma with or without other internal injuries are common.
  • Major injury to the renal vasculature may occur in the absence of hematuria. Hematuria, when present, is usually an early indicator of renal injury. The degree of hematuria, however, does not correlate with the severity of the injury.
  • Significant renal trauma may result in hypovolemic shock.
  • The athlete may initially present as pale, perspiring, tachycardic, and nauseated.
  • Tenderness to palpation of the flank and back is usually present.
  • Muscle guarding may be present.
  • Reflex ileus may occur with a loss of bowel sounds.
  • A mass may be palpable representing either a hematoma or other renal abnormality.
  • Hypotension and shock may be present if there is significant blood loss.
  • Assess for associated injuries to the abdomen, chest, and back.
Diagnostic Tests & Interpretation
Lab
  • Blood counts may show slight leukocytosis with a left shift. Hematocrit may be normal or decreased depending on fluid status. Serum BUN and creatine, as a baseline, help evaluate for pre-existing renal abnormalities.
  • Gross or microscopic hematuria has been reported in over 95% of patients with kidney injuries.
  • Athletes with hematuria, gross or microscopic, following blunt trauma should undergo radiologic assessment.
  • Microscopic hematuria without shock does not necessarily require radiographic evaluation, but can be managed conservatively.
  • Renal imaging is required in all pediatric patients.
  • Renal imaging is required in all adult patients with penetrating trauma and hematuria, gross or microscopic.
  • If physical exam or associated injuries suggest renal injury, renal imaging should be performed for staging.
  • High-resolution CT scan with contrast is the preferred method of renal evaluation following trauma.
  • CT scan is noninvasive, sensitive to hematoma, and sensitive to urine extravasation, and provides additional information regarding other possible organ damage.
  • CT scan is not reliable in evaluating possible renal vein injuries. If venous injury is suspected, venography should be performed.
  • Arteriography is the definitive study to identify parenchymal and vascular injuries.
  • Sonography provides less information compared with CT scan and does not accurately detect vascular injuries.
  • Radionuclide scanning gives limited information and is not especially helpful in staging renal injuries.
  • Although retrograde pyelography is useful in evaluating ureteral injuries, it is not helpful in evaluating renal injuries.
Differential Diagnosis
  • Hematuria:
    • Renal: Congenital anomalies, polycystic kidney, tumor, pyelonephritis, glomerulonephritis, Alport's syndrome, nephrolithiasis
    • Collecting system: Bladder rupture, exercise-induced, tumor, ureteral laceration, urethral laceration, blood dyscrasias
  • Organ injury: Splenic fracture, ruptured viscera, pulmonary contusion, liver fracture
  • Musculoskeletal injury: Fractured rib(s), fractured vertebral body, fractured posterior spinal elements, contusion, muscle strain

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Treatment
  • Aggressive fluid resuscitation in athletes with hypotension or shock
  • Often conservative management if renal contusion is present
  • If staging evaluation of the kidneys shows evidence of vascular involvement, surgical intervention may be required.
  • Evidence of renal venous compromise necessitates emergent intervention.
  • Athletes should be followed until hematuria resolves. Some recommend IV pyelogram (IVP) at 3 mos.
  • Athletes with serious renal trauma should be followed at 3-mo intervals with urinalysis and IVP for at least 1 yr.
Additional Treatment
Additional Therapies
  • Renal injuries are classified according to 5 grades:
    • Grade I: Renal contusion
    • Grade II: Minor lacerations
    • Grade III: Lacerations >1.0 cm without collecting system rupture
    • Grade IV: Parenchymal laceration through renal cortex, medulla, and collecting system
    • Grade V: Complete kidney fracture with vascular compromise
  • Generalized return to conditioning may be required following prolonged convalescence.
  • Specific rehabilitation of chest, abdomen, and back muscles for associated injuries
Surgery/Other Procedures
  • Contusions represent 85–90% of blunt renal injuries. These can be managed nonoperatively.
  • Surgical management of minor and major renal lacerations is controversial. Most clinicians avoid operating unless bleeding is life-threatening.
  • In those cases when surgery is performed, a nephrectomy is usually required.
  • Indications for surgical intervention of complications include expanding uncontained hematoma, pulsatile hematoma, urinary extravasation, vascular injury, nonviable parenchyma, and incomplete staging.
  • Renal exploration is required in ∼2.5% of cases of blunt trauma.
  • Of those requiring renal exploration, the salvage rate is ∼87%.
Ongoing Care
  • Athletes with renal contusions should refrain from participating in contact sports for 6 wks after hematuria resolves.
  • Athletes with extensive renal trauma should be withheld from contact or collision sports for 6–12 mos.
  • Although athletes with a solitary kidney may participate in sports, the decision to participate in contact and collision sports should be weighed on an individual basis.
  • Athletes with solitary kidneys or previous kidney trauma should seriously consider special protective equipment use when they return.
Follow-Up Recommendations
Vascular injuries to the main renal artery carry a poor chance of reconstruction if diagnosis is delayed or the patient is older.
Additional Reading
Armstrong PA, Litsher LJ, Key DW, et al. Management strategies for genitourinary trauma. Hosp Physician. 1998;34:19–25.
Cianflocco AJ. Renal complications of exercise. Clin Sports Med. 1992;11:437–451.
Danzl DF, Rosen P, Barkin R. Emergency medicine: concepts and clinical practice. St. Louis: CV Mosby, 1998.
Feliciano DV, Moore EE, Mattox KL. Trauma. Stamford, CT: Appleton & Lange, 1996.
Gillenwater JY, Grayhack JT, Howards SS, et al. Adult and pediatric urology. St Louis: CV Mosby, 1998.
Mandell J, Cromie WJ, Caldamone AA, et al. Sports-related genitourinary injuries in children. Clin Sports Med. 1982;1:483–493.
Moeller JL. Contraindications to athletic: participation. Physician Sportsmed. 1996;24:57–75.
Codes
ICD9
  • 866.00 Unspecified injury to kidney without mention of open wound into cavity
  • 866.01 Hematoma of kidney, without rupture of capsule, without mention of open wound into cavity
  • 866.02 Laceration of kidney without mention of open wound into cavity
Clinical Pearls
  • Return to sports: Depends on the seriousness of the injury. If surgery (particularly nephrectomy) was required, patient may want to consider avoiding contact or collision sports.
  • Follow-up: Frequent until all symptoms clear then, depending on seriousness of injury, periodic monitoring of kidney function


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