Back stabbers and the renal wounds they inflict

Between 3 to 5 percent of trauma victims present with renal injuries, making the kidney the most frequently injured genitourinary organ.1,2 Although a substantial portion of renal injuries are the result of blunt force, penetrating trauma accounts for 29 percent of all kidney injuries,2 and stab wounds have been shown to comprise approximately 17 percent of all penetrating renal trauma injuries.2,3 Despite its relative scarcity, understanding how to diagnose and treat this potentially deadly condition remains of utmost importance.

Diagnosis and intervention

The diagnosis of renal stab wounds should use a combination of clinical acumen and cross-sectional imaging. Guidelines suggest that intravenous contrast-enhanced computerized tomography should be used in stable patients who have signs of renal trauma or who the clinician suspects may have experienced renal trauma.1 It is important that imaging occurs in both immediate and delayed phases to adequately assess the blood supply and the collecting system.1 Hematuria and hemodynamic instability are insufficient markers of renal injuries, and clinicians should pursue more aggressive imaging if renal injury is suspected.1,4

If a clinician diagnoses a renal stab wound in a stable patient, every effort should be made to manage it conservatively. Intervention is warranted in unstable patients or patients who do not respond appropriately to resuscitative efforts.1 Definitive intervention will vary by specific situation and grade of renal laceration, ranging from angioembolization to surgical repair. Regardless of the management strategy, it is imperative to first control the bleeding and then determine the best means of repairing the kidney and draining the perirenal space.1


To examine the occurrence of patients with knife wounds to the kidneys in the National Trauma Data Bank® (NTDB®) research admission year 2017, medical records were searched using the International Classification of Diseases, 10th Revision Clinical Modification codes. Specifically searched were records that contained E code X99.1 (assault by knife) and a diagnosis code of S37.0 (injury of the kidney). A total of 237 records were found, 216 of which contained a discharge status, including 197 patients discharged to home, seven to acute care/rehab, five to law enforcement, and one to skilled nursing facilities; six died (see Figure 1). Of these patients, 84.8 percent were men, on average 33.7 years of age, had an average hospital length of stay of 6.6 days, an intensive care unit length of stay of 4.1 days, an average injury severity score of 15, and were on the ventilator for an average of four days. Of those patients tested for alcohol, 42 percent (71 out of 168) tested positive.

Figure 1. Hospital Discharge Status

Figure 1. Hospital Discharge Status

Renal injuries comprise a small percent of all traumatic injuries. Penetrating injuries to the kidneys account for an even smaller percentage of all renal injuries, and stab wounds are rarer than gunshot wounds. Therefore, one must be aware of back stabbers, as they may produce a renal injury.

Throughout the year, we highlight these data through brief reports that are published monthly in the Bulletin. The NTDB Annual Report can be found on the American College of Surgeons website as a PDF file. In addition, information is available on our website about how to obtain NTDB data for more detailed study. If you are interested in submitting your trauma center’s data, contact Melanie L. Neal, Manager, NTDB, at


Statistical support for this column was provided by Ryan Murphy, Data Analyst, NTDB.


  1. Morey AF, Brandes S, Dugi DD, et al. Urotrauma: AUA Guideline. J Urol. 2014;192(2):327-335.
  2. Erlich T, Kitrey ND. Renal trauma: The current best practice. Ther Adv Urol. 2018;10(1):295-303.
  3. Kansas BT, Eddy MJ, Mydlo JH, Uzzo RG. Incidence and management of penetrating renal trauma in patients with multiorgan injury: Extended experience at an inner city trauma center. J Urol. 2004;172(4):1355-1360.
  4. Brandes SB, McAninch JW. Urban free falls and patterns of renal injury: A 20-year experience with 396 cases. J Trauma. 1999;47(4):643-649.

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