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Renal Trauma: Injury of the Kidney

Review literature: (Diederichs and Mutze, 2003) (Kawashima et al, 2002) (Meria and Mazeman, 2000) (Vasile et al, 2000).

Etiology of Injuries of the Upper Urinary Tract

Penetrating Injuries:

Gunshot or stab wounds.

Blunt Trauma:

Direct blunt force (contusion, bruising of the abdomen or flank) leads to a rupture the kidneys. Deceleration in high-velocity accidents (falls from height oder motor vehicle accidents) damage the kidney, renal vessels or ureter by the inertia of the mass.

Epidemiology of renal trauma:

• In blunt abdominal trauma, up to 40% present with renal injury.
• In urban areas, 80% of renal injuries occur in the context of polytrauma.
• In ski resorts, 2/3 of renal injuries are due to skiing accidents.
• Children tend to have higher grade injuries, as well as patients with anomalies of the upper urinary tract.
• Penetrating injuries (gunshot or stab wounds) are rare, they play a greater role in the U.S. than in Europe.

Signs and Symptoms of Renal Trauma

Acute signs and symptoms:

• History of abdominal trauma or deceleration injury
• Bruising and hematoma of abdomen or flank
• Abdominal tenderness and tumor
• Flank pain
• Rib fracture
• Hematuria
• Hemodynamic instability, Shock

Late complications of renal trauma:

• Urinoma
• Renal Abscess
• Renal arteriovenous fistula
• Renal hypertension
• Hydronephrosis
• Loss of renal function

Diagnostic Work-up of Renal Trauma

Laboratory examinations:

Urine sediment, blood count, creatinine. The lack of hematuria does not exclude severe renal trauma.

Ultrasound imaging:

Abdominal (renal) ultrasound is a valuable tool for initial evaluation of abdominal injuries without clear evidence of renal injury. If free abdominal fluid, retroperitoneal hematoma, urinoma, hydronephrosis or kidney infarction (with Doppler ultrasound) is seen, abdominal CT is necessary for exact diagnosis.

Computed tomography:

CT is the imaging technique of choice, if there is a high suspicion for renal injury: severe trauma, abnormalities in ultrasound imaging or hematuria. To exclude bladder injury in blunt abdominal trauma, the bladder should be filled with diluted contrast media before CT. [fig. CT imaging of renal trauma]. Contraindication of CT: patients with hemodynamic instability after initial resuscitation and suspicion for intraabdominal bleeding require surgical intervention without further imaging.

CT imaging in renal trauma: left figure: renal trauma grade I (subcapsular hematoma). Right figure: renal trauma grade III (retroperitoneal hematoma, renal laceration >1 cm). With kind permission, Dr. G. Antes, Kempten.

Urography (IVP):

The investigation is largely replaced by computed tomography. IVP may be indicated (as an alternative to CT) to exclude renal injury, e.g. with hematuria and normal ultrasound imaging, and if CT is not available. Urography has also a limited role in intraoperative imaging after emergency laparotomy (single shot IVP).

Classification (Severity) Of Renal Trauma

Classification of the American Association for the Surgery of Trauma (Kozar et al, 2018), advance one grade for bilateral injuries up to grade III:

Grade I:

Renal contusion with hematuria or subcapsular hematoma.

Grade II:

Renal laceration of less than 1 cm, perirenal hematoma confined to the perirenal fascia without active bleeding.

Grade III:

Renal laceration of more than 1 cm, without urinary extravasation, active bleeding with perirenal hematoma confined to the perirenal fascia.

Grade IV:

Renal laceration extending through renal cortex, medulla and collection system with urinary extravasation, vascular injury to segmental renal artery or vein, segmental infarctions without associated active bleeding, active bleeding with hematoma extending beyond the perirenal fascia (into the retroperitoneum or peritoneum).

Grade V:

Completely shattered kidney, vascular injury of the renal hilum, devascularization of the complete kidney with active bleeding.

Treatment of Renal Trauma

Conservative management:

Conservative management is possible in renal trauma with stable circulation and trauma severity grade I–III (no urinary extravasation). Conservative management consists of bed rest until gross hematuria resolves and frequent monitoring of vital signs and blood count. Fever, dropping blood count or flank pain are indications for repeated imaging (ultrasonography or CT) or surgery.

Internal ureteral stent:

Ureteral stenting is indicated for urinary extravasation in grade IV renal injury (MJ/DJ ureteral stent or percutaneous nephrostomy). Large (delayed diagnosed) urinomas are drained percutaneously in addition to ureteral stenting. Antibiotic prophylaxis is often recommended. Place a urethral catheter to prevent reflux alongside the DJ stent.

Surgical Management:

Absolute indications for surgery are:

• Hemodynamic instability after initial resuscitation
• Grade V renal injury with expanding renal hematoma
• Ureteropelvic junction disruption

Relative indications (depending on other factors):

• Urinary extravasation with nonviable renal tissue over 25%
• Associated intraabdominal injuries
• Gunshot wounds
• Suspicious intraoperative IVP, if laparotomy was necessary without preoperative imaging.

Surgical technique:

Transperitoneal exposure using a midline laparotomy, cell saver and packed red blood cells for transfusion should be ready. Early vascular control (near the aorta) before opening of Gerota's fascia improves renal salvage rate. Renal reconstruction can be done with temporary ischemia. Kidney defects may be sutured (renorrhaphy) and covered with omentum majus, absorbable mesh or retroperitoneal fat. Hemostatic agents are helpful in controlling the bleeding tissue. If necessary, urinary drainage is done via nephrostomy.

Indications for nephrectomy: extensive renal or vascular injury, ischemia of the kidney, hemodynamic instability due to bleeding.

References

Diederichs und Mutze 2003 DIEDERICHS, W. ; MUTZE, S.:

[Renal trauma: is open surgery still up to date?].
In: Urologe A
42 (2003), Nr. 3, S. 322–7

Kawashima u.a. 2002 KAWASHIMA, A. ; SANDLER, C. M. ; CORL, F. M. ; WEST, O. C. ; TAMM, E. P. ; FISHMAN, E. K. ; GOLDMAN, S. M.:

Imaging evaluation of posttraumatic renal injuries.
In: Abdom Imaging
27 (2002), Nr. 2, S. 199–213

R. A. Kozar et al., “Organ injury scaling 2018 update: Spleen, liver, and kidney.,” The journal of trauma and acute care surgery, vol. 85, no. 6, pp. 1119–1122, 2018.

Meria und Mazeman 2000 MERIA, P. ; MAZEMAN, E.:

Immediate and delayed management of renal trauma.
In: Eur Urol
37 (2000), Nr. 1, S. 121–30

Vasile u.a. 2000 VASILE, M. ; BELLIN, M. F. ; HELENON, O. ; MOUREY, I. ; CLUZEL, P.:

Imaging evaluation of renal trauma.
In: Abdom Imaging
25 (2000), Nr. 4, S. 424–30

  Deutsche Version: Nierentrauma