Radiographic predictors of need for angiographic embolization after traumatic renal injury

Background: Although the American Association of the Surgery for Trauma Organ Injury Scale is the gold standard for staging renal trauma, it does not address characteristics of perirenal hematomas that may indicate significant hemorrhage. Angiographic embolization has become well established as an effective method for achieving hemostasis. We evaluated two novel radiographic indicators-perirenal hematoma size and intravascular contrast extravasation (ICE)-to test their association with subsequent angiographic embolization. Methods: Among 194 patients with renal trauma between 1999 and 2004, 52 having a grade 3 (n = 33) or grade 4 (n = 19) renal laceration were identified. Computed tomography scans were reviewed by a staff radiologist and urologist blinded to outcomes. ICE was defined as contrast within the perirenal hematoma during the portal venous phase having signal density matching contrast in the renal artery. Hematoma size was determined in four ways: hematoma area (HA), hematoma to kidney area ratio (HKR), difference between hematoma and kidney area (HKD), and perirenal hematoma rim distance (PRD). Results: Of the 52 patients, 8 had ICE and 4 of these (50%) required embolization, whereas none of the 42 (0%) patients without ICE needed embolization (p = 0.001). Likewise, all four measures of perirenal hematoma size assessed were significantly greater in patients receiving embolization [HA (128.3 vs. 75.4 cm², p = 0.009), HKR (2.75 vs. 1.65, p = 0.008), HKD (76.5 vs. 30.2 cm², p = 0.006), and PRD (4.0 vs. 2.5 cm, p = 0.041)]. Conclusion: Perirenal hematoma size and ICE are readily detectible radiographic features and are associated with the need for angiographic embolization.