The 2018 update of the American Association for the Surgery of Trauma (AAST) renal injury scale is the most widely used grading system for renal trauma at the time of writing (late 2018) 8. Severity is assessed according to the depth of renal parenchymal damage and involvement of the urinary collecting system and renal vessels.
- subcapsular hematoma or contusion, without laceration
- superficial laceration ≤1 cm depth not involving the collecting system (no evidence of urine extravasation)
- perirenal hematoma confined within the perirenal fascia
- laceration >1 cm not involving the collecting system (no evidence of urine extravasation)
- vascular injury or active bleeding confined within the perirenal fascia
- laceration involving the collecting system with urinary extravasation
- laceration of the renal pelvis and/or complete uretopelvic disruption
- vascular: injury to segmental renal artery or vein
- segmental infarctions without associated active bleeding (i.e. due to vessel thrombosis)
- active bleeding extending beyond the perirenal fascia (i.e. into the retroperitoneum or peritoneum)
- grade V
NB. advance one grade for bilateral injuries up to grade III.
If a renal injury is detected on a routine trauma portal venous phase CT of the abdomen without evidence of urine extravasation, then a delayed phase at 5-15 minutes should be considered to assess for urine extravasation, especially if there are clinical signs of collecting system injury (e.g. hematuria or blood at the meatus) 5. This should not necessarily be performed if the patient is unstable or if there are other large, life-threatening injuries.
- 1. Moore EE, Shackford SR, Pachter HL et-al. Organ injury scaling: spleen, liver, and kidney. J Trauma. 1989;29 (12): 1664-6. - Pubmed citation
- 2. Kawashima A, Sandler CM, Corl FM et-al. Imaging of renal trauma: a comprehensive review. Radiographics. 21 (3): 557-74. Radiographics (full text) - Pubmed citation
- 3. Smith J, Kenney P. Radiologic Clinics of North America. 2003;41 (5): . doi:10.1016/S0033-8389(03)00075-7
- 4. Park SJ, Kim JK, Kim KW et-al. MDCT Findings of renal trauma. AJR Am J Roentgenol. 2006;187 (2): 541-7. doi:10.2214/AJR.05.0543 - Pubmed citation
- 5. Stuhlfaut JW, Lucey BC, Varghese JC, Soto JA. Blunt abdominal trauma: utility of 5-minute delayed CT with a reduced radiation dose. (2006) Radiology. 238 (2): 473-9. doi:10.1148/radiol.2382042096 - Pubmed
- 6. Ramchandani P, Buckler PM. Imaging of genitourinary trauma. AJR Am J Roentgenol. 2009;192 (6): 1514-23. doi:10.2214/AJR.09.2470 - Pubmed citation
- 7. Srinivasa RN, Akbar SA, Jafri SZ et-al. Genitourinary trauma: a pictorial essay. Emerg Radiol. 2009;16 (1): 21-33. doi:10.1007/s10140-008-0738-x - Pubmed citation
- 8. Kozar RA, Crandall M, Shanmuganathan K, Zarzaur BL, Coburn M, Cribari C, Kaup K, Schuster K, Tominaga GT. Organ injury scaling 2018 update: Spleen, liver, and kidney. (2018) The journal of trauma and acute care surgery. 85 (6): 1119-1122. doi:10.1097/TA.0000000000002058 - Pubmed