It should be emphasized that patients with a preexisting solitary kidney are at especially high risk of renal failure because injury to the single kidney may result in substantially reduced renal function.

Labs and Imaging

All patients with suspected or confirmed renal trauma should have a baseline creatinine measurement. In animal studies, serum creatinine was noted to remain normal for eight hours after bilateral nephrectomy. Therefore, most initial creatinine levels will reflect preexisting renal disease rather than new dysfunction caused by the trauma.

A urine sample should be inspected for both gross and microscopic hematuria, although this may not be a reliable indicator of trauma. One study demonstrated up to 9 percent of cases without hematuria were associated with major injury such as disruption of the ureteropelvic junction, pedicle injuries, and segmental arterial thrombosis.

Grade A: Urine from a patient with suspected renal injury should be inspected for haematuria (visually and by dipstick analysis).

Grade C: Creatinine levels should be measured to identify patients with impaired renal function prior to injury.¹

Although ultrasound can be used to identify lacerations and perinephric hematomas, computed tomography (CT) scans are more sensitive and specific. Angiography offers the added benefit of therapeutic embolization but is typically only used when there is a known injury with potential for hemostasis.

CT with intravenous contrast is necessary to assess for pedicle injury, which is indicated by a lack of contrast enhancement. If suspicion of pedicle injury is high or there are associated signs of injury, for example, hematoma or free fluid, delayed CT scans should be performed 10 to 15 minutes after contrast injection to assess for collecting-system injury that can be missed using a routine CT imaging protocol.

Grade A*: Blunt trauma patients with visible (gross) or non-visible haematuria and haemodynamic instability should undergo radiographic evaluation.

Grade B: Immediate imaging is recommended for all patients with a history of rapid deceleration injury and/or significant associated injuries.

Grade A*: All patients with or without haematuria after penetrating abdominal or lower thoracic injury require urgent renal imaging.

Grade C: Ultrasound alone should not be used to set the diagnosis of renal injury since it cannot provide sufficient information. However, it can be informative during the primary evaluation of polytrauma patients and for the follow-up of recuperating patients.

Grade A: A CT scan with enhancement of intravenous contrast material and delayed images is the gold standard for the diagnosis and staging of renal injuries in haemodynamically stable patients.¹