Renal and extrarenal predictors of nephrectomy from The National Trauma Data Bank reviewed

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Mar 13 2006

The management of renal trauma has become increasingly conservative with multiple series showing renal preservation after high grade injury.

Absolute indications for nephrectomy in renal trauma have narrowed to persistent, life-threatening hemorrhage. Complications that once required open surgery are now managed by less invasive means, for example active arterial bleeding can be controlled with angioembolization, while perinephric abscesses and urinomas can be treated successfully with percutaneous drainage and indwelling ureteral stents.

Despite the trend toward renal preservation a population based study suggested that nephrectomy is the most commonly performed renal surgery for kidney injuries, occurring at a much higher rate than reported from specialized centers with an interest in renal trauma. A recent review by Hunter Wessells and colleagues from the University of Washington in Seattle aims to evaluate the factors predictive of nephrectomy across a large sample of trauma centers. The review also examines the importance of extrarenal factors in the decision making surrounding renal salvage. The review is published in the March 2006 issue of the Journal of Urology.

Data was obtained from the National Trauma Data Bank (NTDB) from 1994 to 2003 and examined retrospectively to determine extrarenal and renal factors predictive of nephrectomy. The NTDB is a voluntary data repository managed by the American College of Surgeons that contains all trauma admissions to 268 participating trauma centers from 36 states.

Analysis of the results showed that a renal injury was present in 8,465 patients out of 742,774 injured patients (1.14%). The majority of injuries were secondary to blunt trauma (81%). Only 0.5% of blunt renal injury cases underwent repair compared with 15% of those with penetrating injuries. Nephrectomy was performed in 4.1% (289) and 21% (333) of those injured as a result of a blunt or penetrating mechanism, respectively. The nephrectomy rate in patients undergoing exploration for blunt injuries was thus 89%. Penetrating injuries were explored 36% of the time and almost half were able to be managed by renorraphy.

Hospital mortality in patients with renal injury was 16% (251) and 10% (689) for penetrating and blunt injuries, respectively. On multivariate analysis renal injury severity was the strongest predictor for nephrectomy. The relative risk of nephrectomy for grade V renal injuries was 146 and 33 in the blunt and penetrating models, respectively. The need for laparotomy and surgery on other abdominal organs, particularly vascular injuries, predicted the need for nephrectomy in patients with both blunt and penetrating injuries.

In summary, this review confirms that the strongest predictor of nephrectomy in the renal injured patient is the severity of the renal injury. Surgical intervention is much more common in those with penetrating injuries, while blunt injured patients undergoing surgery almost exclusively undergo nephrectomy. Operations on other abdominal organs impart a higher risk of nephrectomy regardless of renal injury grade, suggesting that the kidney is removed as a damage control measure due to insufficient experience with renal salvage techniques.

By Michael J. Metro, MD