IMAGING

Development of renal scars on CT after abdominal trauma: does grade of injury matter?
Dunfee BL, Lucey BC, Soto JA
Department of Radiology, Division of Body Imaging, Boston University Medical Center, Boston, MA, USA
AJR Am J Roentgenol. 2008; 190: 1174-9

• Objective: The objective of our study was to determine whether there is an association between the grade of a traumatic renal injury and the subsequent development of renal parenchymal scars on CT.
• Materials and Methods: We performed a retrospective study encompassing all acute trauma patients admitted to our institution over a 42-month period found to have renal parenchyma injuries on initial MDCT and also to have undergone a follow-up CT performed at least 1 month after trauma. We identified 54 patients who sustained blunt (n = 44) or penetrating (n = 10) abdominal trauma. The renal injuries were graded by two radiologists according to the Organ Injury Scaling Committee of the American Association for the Surgery of Trauma (AAST), grades I through V. Follow-up CT was reviewed for the presence of parenchymal distortion, scarring, or perfusion defects.
• Results: Of the 54 patients, 12 had grade I injury, eight had grade II injury, 22 had grade III injury, 10 had grade IV injury, and two had grade V injury. Grades I and II traumatic renal injuries were undetectable on follow-up CT. Grade III injuries resulted in the development of renal scars in 14 of 22 (64%) patients. Scarring resulted in all patients with grades IV and V injuries.
• Conclusion: Grades I and II renal injuries heal completely, whereas higher grades of renal trauma result in permanent parenchymal scarring. Hence, incidentally discovered renal scars in patients with a history of minor renal trauma should be attributed tentatively to other causes that may or may not require additional investigation.
  
  
• Editorial Comment
  Since the preservation of long-term renal function is often better when renal injuries are treated nonoperatively, in stable patients, conservative management may be preferable even in high-grade injuries. Surgery or interventional radiographic procedures will be used mainly in patients presenting extensive devitalized renal tissue, active hemorrhage, or a large injury to the collecting system with progressive renal compression on follow-up or with ureteral disruption, Overall, with modern management techniques, renal salvage rates approach 85-90%. This report focuses on the follow-up of traumatic blunt or penetrating renal parenchymal damage. The authors used initial and a follow-up CT, which was performed at least 1 month after trauma. The authors concluded that Grades I and II renal injuries heal completely but most of Grade III an all Grades IV and V were associated with variable degree of parenchymal distortion, scarring or perfusion defects. The healing and scar formation were directly correlated with the severity of injury. This is an important observation since areas of parenchymal renal scarring is not an infrequent finding on abdominal CT performed for many other clinical reasons. Radiologist should consider sequelae of high grade renal lesion among the causes of renal scarring such as pyelonephritis, renal emboli and systemic vasculites. We have also to remember that other late complications after renal trauma are hydronephrosis and calculus formation (both secondary to scarring in the region of renal pelvis), arteriovenous fistula (usually after stab wound) and delayed hypertension.

Dr. Adilson Prando
Chief, Department of Radiology and
Diagnostic Imaging, Vera Cruz Hospital
Campinas, São Paulo, Brazil
E-mail: adilson.prando@gmail.com