Kidney Injuries

Trauma continues to be the leading cause of death among people younger than age 45, with the main cause of death attributed to injuries to intra-abdominal organs. Renal trauma is present in as many as 10% of patients with abdominal trauma.

Ninety percent of kidney injuries are due to blunt trauma. The kidney is the 3^rd most common solid organ injured as a result of blunt trauma. Mechanisms of blunt renal trauma include rapid deceleration (ie motor vehicle collisions, falls) and direct blows to the flank. The kidney lies in a bed of fat contained within Gerota’s fascia and is fixed primarily at 2 points: the ureter and the vascular pedicle. Because of this limited fixation, the kidney can be dislocated, resulting in tearing of the collecting system at the ureteropelvic junction or of the vasculature. The majority of blunt renal injuries, however, are low-grade, which accounts for the shift in management from operative to non-operative management over the last decade coupled with advancements in imaging modalities. CT imaging has become the primary imaging modality to evaluate for traumatic kidney injuries in the acute setting, which is both sensitive and specific for demonstrating lacerations, infarcts, urine extravasation, and other associated intra-abdominal organ injuries as well as accurately defining arterial injury. Angiography is reserved for those patients who demonstrate on-going bleeding and need arterial embolization.   

Delayed bleeding from kidney injury after non-operative management is uncommon; approximately 1 out of every 10 patients will require surgical intervention for either delayed or on-going bleeding (Velmahos, 2003).   Most perinephric fluid collections and urinomas can be treated with percutaneous drainage and active hemorrhage can often be managed with angioembolization. In order to determine the appropriate management for renal injury, the American Associate for the Surgery of Trauma (AAST) has defined renal trauma in 5 grades:

   

 

Ureteropelvic junction injuries will rarely heal spontaneously and therefore often require surgical repair.  Nearly all penetrating renal injuries require surgical management. Penetrating traumas with no other intra-abdominal injuries and a grade 1-2 renal injury, however, can often be managed conservatively with relatively low complication rates. This is in contrast to grade 3-4 injuries, which are often complicated by delayed renal bleeding when managed conservatively and often required surgical repair (Wessels 1997).  

Thanks to Dr. Andrea Olivas for this post.