UROGENITAL TRAUMA

Predictors of the Need for Nephrectomy after Renal Trauma
Davis KA, Reed RL 2nd, Santaniello J, Abodeely A, Esposito TJ, Poulakidas SJ, Luchette FA
Division of Trauma, Surgical Critical Care and Burns, Department of Surgery, Loyola University Medical Center, Stritch School of Medicine, Maywood, IL, USA
J Trauma. 2006; 60: 164-9; discussion 169-70

• Background: Initial management of solid organ injuries in hemodynamically stable patients is nonoperative. Therefore, early identification of those injuries likely to require surgical intervention is key. We sought to identify factors predictive of the need for nephrectomy after trauma.
• Methods: This is a retrospective review of renal injuries admitted over a 12-year period to a Level I trauma center.
• Results: Ninety-seven patients (73% male) sustained a kidney injury (mean age, 27 +/- 16; mean Injury Severity Score, 13 +/- 10). Of the 72 blunt trauma patients, 5 patients (7%) underwent urgent nephrectomy, 3 (4%) had repair and/or stenting, and 89% were observed despite a 29% laparotomy rate for associated intraabdominal injuries in this group. Twenty-five patients with penetrating trauma underwent eight nephrectomies (31%), one partial nephrectomy, and two renal repairs. Regardless of the mechanism of injury, patients requiring nephrectomy were in shock, had a higher 24-hour transfusion requirement, and were more likely to have a high-grade renal laceration (all p < 0.05). Bluntly injured patients requiring nephrectomy had more concurrent intraabdominal injuries (p < 0.0001). Overall, patients after penetrating trauma were more severely injured, had higher 24-hour transfusion requirements, and a higher nephrectomy rate (all p < 0.05). Despite a higher injury severity in the penetrating group, however, mortality was higher in the bluntly injured group (p < 0.0001). Univariate predictors for nephrectomy included: revised trauma score, injury severity score, Glasgow Coma Scale score, shock on presentation, renal injury grade, and 24-hour transfusion requirement. No patient with a mild or moderate renal injury required nephrectomy, whereas 6 of 12 (50%) grade 4 injuries and 7 of 8 (88%) grade 5 injuries required nephrectomy. Multiple logistic regression analysis confirmed penetrating injury, renal injury grade, and Glasgow Coma Scale score as predictive of nephrectomy.
• Conclusion: Overall, injury severity, severity of renal injury grade, hemodynamic instability, and transfusion requirements are predictive of nephrectomy after both blunt and penetrating trauma. Nephrectomy is more likely after penetrating injury.
  
  
• Editorial Comment
  This study confirms the well-established concept that most renal injuries are AAST grade 1-3, and can be safely managed non-operatively. Predictors for nephrectomy were shock, higher AAST grade of renal injury (4 - 5), ongoing transfusion requirement, and associated intraabdominal injuries. Grade 5 injuries, by definition are potentially life-threatening with avulsion of the renal hilum or a completely shattered kidney. That the nephrectomy rate in this study for Grade 5 kidney injuries approached 90% is not surprising. In unstable kidney trauma patients with ongoing blood loss, nephrectomy is part of a “damage control” approach to stabilize the patient, get them off the OR stable, and quickly into the ICU for resuscitation.
  Clearly, opening up Gerota’s fascia and releasing the tamponade effect of the retroperitoneal hematoma may result in uncontrollable bleeding and subsequent nephrectomy. Thus, there are 2 main ways to avoid unnecessary nephrectomy: 1) For the stable trauma patient, image the abdomen with CT with delayed images in order to properly stage the kidney injury. With an accurate kidney injury stage and location of the retroperitoneal hematoma, patients can then be selected for surgery or expectant management. 2) Retroperitoneal hematomas that are not zone 1, stable, non-expanding, non-pulsatile, and contained do not demand exploration. Zone 1 hematomas, namely midline supramesocolic or midline inframesocolic, from a blunt or penetrating mechanism demand exploration. Zone 2, lateral perinephric hematomas should be selectively explored for penetrating trauma, and typically observed for blunt trauma (1).
  In Davis et al, half of Grade 4 injuries ended up with nephrectomy. This is higher then prior reports, but again nephrectomy may have been performed as “damage control” in the face of instability and associated injuries. Prior reports, however, have demonstrated that most Grade 4 renal injuries can be managed expectantly, with the kidney being re-imaged by CT with intravenous contrast and delayed images (3 to 5 days after initial injury) to assess for persistent urinary leakage. Worsened or unimproved leak warrants ureteral stent placement of urinoma drain placement.

Reference
1. Brandes SB: Trauma to the Genitourinary Tract. In: Rakel RE, Bope ET (eds.), Conn’s Current Therapy. 57th ed., Philadelphia, WB Saunders, 2005.

Dr. Steven B. Brandes
Associate Professor, Division of Urologic Surgery
Washington University in St. Louis
St. Louis, Missouri, USA