The kidney is injured in approximately 10 percent of all significant blunt abdominal trauma. Of those, 13 percent are sports-related when the kidney, followed by testicle, is most frequently involved. However, the most frequent cause by far is traffic collisions, followed by falls. The consequences are usually less severe than injuries involving other internal organs.
In blunt injury, imaging is indicated if there is gross hematuria, or if the patient exhibits shock together with either gross or microscopic hematuria.
The imaging modality of choice is contrast-enhanced, computed tomography (CT) which is readily available in most emergency departments of moderate or above size. Scan times have become shorter with each generation of scanners and current scans are quick and accurately demonstrate renal injuries together with associated injuries to other abdominal or retroperitoneal organs.
Unlike ultrasound examination (FAST), CT provides anatomic and functional information that allows for accurate grading of the injury which is partly responsible for a growing trend toward conservative management (intravenous fluids, close monitoring, watchful waiting) of renal trauma. Conservative management does not apply in situations where extensive urinary extravasation or devitalized areas of renal parenchyma are found and especially if associated with injuries to other abdominal organs; these cases are complication-prone and much more likely to require surgery. That being said, a retrospective study suggests that primary conservative treatment of blunt kidney rupture seems to lead to less surgery, especially less open surgery, and less blood and renal parenchyma loss, compared to a strategy of initial surgery.
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