AAST Kidney OIS AAST Kidney Organ Injury Scale

{
  "categories": [
    {
      "outcome_code": "I",
      "qualifying_findings": [
        "subcapsular_hematoma_under_3_5_cm_without_active_bleeding",
        "parenchymal_contusion_without_laceration"
      ]
    },
    {
      "outcome_code": "II",
      "qualifying_findings": [
        "parenchymal_laceration_length_under_2_5_cm",
        "hematoma_rim_distance_under_3_5_cm_without_active_bleeding"
      ]
    },
    {
      "outcome_code": "III",
      "qualifying_findings": [
        "parenchymal_laceration_length_at_least_2_5_cm",
        "hematoma_rim_distance_at_least_3_5_cm_without_active_bleeding",
        "partial_kidney_infarction",
        "contained_vascular_injury_without_active_bleeding",
        "collecting_system_laceration_or_urinary_extravasation"
      ]
    },
    {
      "outcome_code": "IV",
      "qualifying_findings": [
        "active_bleeding_from_kidney",
        "pararenal_extension_of_hematoma",
        "complete_or_near_complete_infarction_without_active_bleeding",
        "multifragmented_kidney_without_active_bleeding",
        "complete_or_near_complete_UPJ_disruption"
      ]
    },
    {
      "outcome_code": "V",
      "qualifying_findings": [
        "main_renal_artery_or_vein_laceration_or_transection_with_active_bleeding",
        "complete_or_near_complete_infarction_with_active_bleeding",
        "multifragmented_kidney_with_active_bleeding"
      ]
    }
  ],
  "grading_algorithm": {
    "classification_unit": "one_injured_kidney",
    "highest_finding_rule": "Assign the highest grade supported by imaging, operative or pathologic findings for that kidney.",
    "bilateral_rule": "Grade the right and left kidneys separately; do not collapse bilateral injuries into one grade.",
    "multiple_injury_rule_2025": "Multiple findings in one kidney are not upgraded merely because they are multiple; use only the highest qualifying finding.",
    "management_separation": "The anatomic grade is not a hemodynamic class and does not by itself determine observation, embolization, stenting, operation or nephrectomy."
  },
  "measurement_and_definition_contract": {
    "laceration_length": "Measure the longest laceration length on a single axial CT image; the grade II-versus-III boundary is 2.5 cm.",
    "hematoma_rim_distance": "Measure the longest perpendicular distance from the renal parenchymal border to the bulk hematoma border on axial CT within the superior and inferior kidney margins; exclude a thin sliver beyond the bulk and bleeding originating from another organ.",
    "subcapsular_boundary": "A subcapsular hematoma under 3.5 cm without active bleeding supports grade I; state how it was measured and do not substitute percentage surface area from an older scale.",
    "pararenal_hematoma": "Pararenal extension crosses the right border of the IVC for a right-sided bleed, the left border of the aorta for a left-sided bleed, or extends inferior to the aortic bifurcation; it supports grade IV.",
    "multifragmented_kidney": "MFK means at least three injured parenchymal segments with fluid or blood between them; active bleeding separates grade V from grade IV.",
    "active_bleeding": "Vascular contrast outside a vessel demonstrated on arterial, venous or delayed phase; active bleeding is distinct from a contained vascular lesion.",
    "contained_vascular_injury": "Pseudoaneurysm, arteriovenous fistula, dissection, thrombosis, intimal flap or mural hematoma without active bleeding supports grade III.",
    "infarction": "Record partial versus complete or near-complete infarction and whether active bleeding is present because those combinations map to grades III, IV or V."
  },
  "CT_and_provenance_gate": {
    "required_inputs": [
      "injured_side",
      "contrast_phase_availability",
      "laceration_axial_length_cm",
      "hematoma_type_and_HRD_cm",
      "active_bleeding_status",
      "vascular_injury_type",
      "infarction_extent",
      "collecting_system_or_UPJ_injury",
      "MFK_status",
      "hemodynamic_status_recorded_separately"
    ],
    "phase_rule": "Evaluate an adequately timed contrast-enhanced trauma CT and obtain delayed excretory-phase imaging when collecting-system injury is suspected; absent or degraded phases must be reported as a limitation.",
    "no_CT_rule": "In an unstable patient taken directly to intervention, grade from the highest operative or pathologic finding and identify that provenance rather than inventing CT measurements.",
    "uncertainty_rule": "If a threshold measurement or active-bleeding state is unresolved, return the bounded competing grades and the missing acquisition or measurement."
  },
  "version_boundary_2018_to_2025": {
    "laceration_threshold": "The 2018 depth cutoff of 1 cm was replaced by a 2.5 cm axial length cutoff in 2025.",
    "hematoma_measurement": "The 2025 scale added a 3.5 cm subcapsular and hematoma-rim-distance framework plus an explicit pararenal-extension definition.",
    "collecting_system": "Collecting-system laceration or urinary extravasation moved from grade IV in 2018 to grade III in 2025; complete or near-complete UPJ disruption remains grade IV.",
    "vascular_and_bleeding": "Contained vascular injury without active bleeding is grade III; active renal bleeding is grade IV unless a grade-V main-vessel, complete-infarction or bleeding-MFK pattern is present.",
    "fragmented_kidney": "The undefined 2018 term shattered kidney was replaced by MFK, defined as at least three injured parenchymal segments separated by fluid or blood.",
    "upgrade_rule": "The 2018 kidney footnote advanced bilateral injuries by one grade up to grade III; the 2025 system instead grades each kidney separately and does not upgrade multiple injuries.",
    "interoperability_guard": "Never mix a 2018 code with 2025 criteria. Preserve the version when reading literature, registries, protocols or prior reports, because grade-specific cohorts and management statements may not transport across the revision."
  },
  "current_management_context": {
    "primary_driver": "Hemodynamic response, ongoing bleeding, associated injuries, renal anatomy and available trauma, urology and interventional-radiology expertise dominate acute management.",
    "stable_patient": "Modern AUA, WSES-AAST, EAST and EAU guidance generally supports nonoperative renal-preserving management for stable or stabilized patients across a broad range of anatomic grades, with monitoring and selective intervention for specific complications.",
    "bleeding": "Active extravasation, pseudoaneurysm, arteriovenous fistula, enlarging hematoma, transfusion need or clinical deterioration may support angiography and selective embolization in a suitable patient; instability without durable response can require immediate operative hemorrhage control.",
    "urinary_leak": "A stable parenchymal collecting-system leak can often be observed initially; suspected pelvis or proximal-ureter avulsion, infected or enlarging urinoma, obstruction, persistent leak, pain or fever can require drainage or stenting. Do not treat every 2025 grade-III leak as an automatic intervention.",
    "follow_up": "Repeat imaging is driven by deep injury anatomy and clinical concern such as fever, falling hematocrit, pain or ongoing blood loss. Older guideline recommendations keyed to 2018 grades must be mapped by anatomy rather than copied to the 2025 number.",
    "nephrectomy_guard": "Grade V does not automatically mean nephrectomy in a stabilized selected patient; life-threatening instability and irreparable anatomy may require surgery, while renal preservation can remain possible in expert centers."
  },
  "risk_and_evidence_limits": {
    "intent_of_revision": "The 2025 revision was designed to better align objective contemporary imaging findings with need for bleeding-control intervention, but it is not a calibrated individual mortality, nephrectomy or renal-function calculator.",
    "derivation_boundary": "The evidence underlying thresholds is predominantly observational trauma data. Mechanism, physiology, transfusion, associated injury and local practice alter outcome beyond the grade.",
    "historical_data_guard": "Do not attach complication or intervention percentages from a 2018-grade cohort to a 2025 grade without reclassifying the original anatomy.",
    "negative_guard": "A lower grade does not exclude clinically important hematuria, delayed vascular complication or injury to another organ; a higher grade does not prove ongoing bleeding or treatment failure."
  },
  "missing_input_behavior": [
    "If side is unknown in bilateral trauma, do not return a single kidney grade.",
    "If laceration length is near 2.5 cm or HRD near 3.5 cm and measurement quality is inadequate, return the adjacent grades and request an axial measurement.",
    "If contrast phases cannot distinguish contained vascular injury from active bleeding, preserve grade III-versus-IV uncertainty and request phase-appropriate review.",
    "If urinary extravasation is present but UPJ continuity is unresolved, state grade III-versus-IV and request delayed-phase or urologic correlation.",
    "If fragmented parenchyma is present but segment count or intervening fluid is unknown, do not call MFK.",
    "If the report or source says only AAST grade without a version, return version ambiguity rather than translating it silently."
  ],
  "supporting_sources": [
    {
      "role": "current_primary_scale",
      "citation": "Keihani et al. J Trauma Acute Care Surg. 2025;98:448-451",
      "doi": "10.1097/TA.0000000000004509",
      "pmid": "39836096"
    },
    {
      "role": "open_imaging_table",
      "citation": "Jeon. Korean Journal of Interventional Radiology. 2025",
      "doi": "10.64961/kjir.2025.00052"
    },
    {
      "role": "predecessor_scale",
      "citation": "Kozar et al. J Trauma Acute Care Surg. 2018;85:1119-1122",
      "doi": "10.1097/TA.0000000000002058"
    },
    {
      "role": "urology_guideline",
      "citation": "AUA Urotrauma Guideline Amendment 2020",
      "doi": "10.1097/JU.0000000000001408"
    },
    {
      "role": "multidisciplinary_guideline",
      "citation": "Coccolini et al. WSES-AAST. 2019",
      "doi": "10.1186/s13017-019-0274-x",
      "pmcid": "PMC6886230"
    },
    {
      "role": "trauma_guideline",
      "citation": "Aziz et al. EAST. 2023",
      "doi": "10.1186/s12893-023-01914-x",
      "pmcid": "PMC9881253"
    }
  ],
  "source_locator": "Keihani et al. 2025, PMID 39836096, current AAST multidisciplinary revision; Jeon 2025, DOI 10.64961/kjir.2025.00052, Table 1 and definitions; AAST official OIS revision page; Kozar et al. 2018 predecessor table and kidney footnote; AUA 2020, WSES-AAST 2019, EAST 2023 and current EAU urological-trauma guidance for anatomy- and physiology-aware management boundaries."
}