AAST kidney injury scale

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The 2018 update of the American Association for the Surgery of Trauma (AAST) renal injury scale^1,6is the most widely used grading system for renal trauma at the time of writing (late ~~2016~~2018)⁸. Severity is assessed according to the depth of renal parenchymal damage and involvement of the urinary collecting system and renal vessels.

Classification

grade I: ~~contusion~~
- subcapsular haematoma or ~~non-enlarging~~ ~~subcapsular perirenal haematoma~~contusion, ~~and no~~without laceration
grade II:
- superficial laceration <1≤1 cm depth ~~and does~~ not ~~involve~~involving the ~~collecting system (no evidence of urine extravasation), non-expanding perirenal haematoma confined to retroperitoneum~~
- ~~grade III:~~ ~~laceration >1 cm without extension into the renal pelvis or~~ collecting system (no evidence of urine extravasation)
- perirenal haematoma confined within the perirenal fascia
grade III:
- laceration >1 cm not involving the collecting system (no evidence of urine extravasation)
- vascular injury or active bleeding confined within the perirenal fascia
grade IV
- laceration ~~extends to~~involving the collecting system with urinary extravasation
- laceration of the renal pelvis ~~or urinary extravasation~~and/or complete uretopelvic disruption
- vascular: injury to ~~main~~ segmental renal artery or vein ~~with contained haemorrhage~~
- segmental infarctions without associated ~~lacerations~~active bleeding (i.e. due to vessel thrombosis)
- ~~expanding subcapsular haematomas compressing~~active bleeding extending beyond the ~~kidney~~perirenal fascia (i.e. into the retroperitoneum or peritoneum)
grade V
- shattered kidney
- avulsion of renal hilum or laceration of the main renal artery or vein: devascularisation of a kidney due to hilar injury
- ~~ureteropelvic avulsions~~
- ~~complete laceration or thrombus of the main renal artery or vein~~devascularised kidney with active bleeding

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. haematuria 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.

-The American Association for the Surgery of Trauma (AAST) renal injury scale 1,6 is the most widely used grading system for <a href="/articles/renal-trauma-1">renal trauma</a> at the time of writing (late 2016). Severity is assessed according to the depth of renal parenchymal damage and involvement of the urinary collecting system and renal vessels.<h4>Classification</h4><ul>
+The 2018 update of the American Association for the Surgery of Trauma (AAST) renal injury scale is the most widely used grading system for <a href="/articles/renal-trauma-1">renal trauma</a> 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.<h4>Classification</h4><ul>
~~-grade I: contusion or non-enlarging <a href="/articles/subcapsular-perirenal-haematoma">subcapsular perirenal haematoma</a>, and no laceration</li>~~
+grade I: <ul><li>subcapsular haematoma or contusion, without laceration</li></ul>
+</li>
-grade II: superficial laceration <1 cm depth and does not involve the collecting system (no evidence of urine extravasation), non-expanding perirenal haematoma confined to retroperitoneum</li>
+grade II:<ul>
+<li>superficial laceration ≤1 cm depth not involving the collecting system (no evidence of urine extravasation)</li>
+<li>perirenal haematoma confined within the <a title="Perirenal fascia" href="/articles/perirenal-fascia">perirenal fascia</a>
+</li>
+</ul>
+</li>
~~-grade III: laceration >1 cm without extension into the renal pelvis or collecting system (no evidence of urine extravasation)</li>~~
+grade III:<ul>
+<li>laceration >1 cm not involving the collecting system (no evidence of urine extravasation)</li>
+<li>vascular injury or active bleeding confined within the <a title="perirenal fascia" href="/articles/perirenal-fascia">perirenal fascia</a>
+</li>
+</ul>
+</li>
~~-<li>laceration extends to renal pelvis or urinary extravasation</li>~~
~~-<li>vascular: injury to main renal artery or vein with contained haemorrhage</li>~~
~~-<li>segmental infarctions without associated lacerations</li>~~
~~-<li>expanding subcapsular haematomas compressing the kidney</li>~~
+<li>laceration involving the collecting system with urinary extravasation</li>
+<li>laceration of the renal pelvis and/or complete uretopelvic disruption</li>
+<li>vascular: injury to segmental <a title="Renal artery" href="/articles/renal-artery">renal artery</a> or <a title="Renal vein" href="/articles/renal-vein-1">vein</a>
+</li>
+<li>segmental infarctions without associated active bleeding (i.e. due to vessel thrombosis)</li>
+<li>active bleeding extending beyond the <a title="Perirenal fascia" href="/articles/perirenal-fascia">perirenal fascia</a> (i.e. into the <a title="Retroperitoneum" href="/articles/retroperitoneum">retroperitoneum</a> or <a title="Peritoneum" href="/articles/peritoneum">peritoneum</a>)</li>
~~-<li>avulsion of renal hilum: <a href="/articles/renal-vascular-pedicle-injury-2">devascularisation of a kidney due to hilar injury</a>~~
+<li>avulsion of renal hilum or laceration of the main <a title="Renal artery" href="/articles/renal-artery">renal artery</a> or <a title="Renal vein" href="/articles/renal-vein-1">vein</a>: <a href="/articles/renal-vascular-pedicle-injury-2">devascularisation of a kidney due to hilar injury</a>
~~-<li>ureteropelvic avulsions</li>~~
~~-<li>complete laceration or thrombus of the main renal artery or vein</li>~~
+<li>devascularised kidney with active bleeding</li>

References changed:

8. Kozar R, Crandall M, Shanmuganathan K et al. Organ Injury Scaling 2018 Update: Spleen, Liver, and Kidney. J Trauma Acute Care Surg. 2018;85(6):1119-22. <a href="https://doi.org/10.1097/ta.0000000000002058">doi:10.1097/ta.0000000000002058</a>

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AAST kidney injury scale

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