Revised Atlanta classification of acute pancreatitis

{
  "categories": [
    {
      "outcome_code": "mild",
      "organ_failure": "absent",
      "local_or_systemic_complication": "absent"
    },
    {
      "outcome_code": "moderately-severe",
      "organ_failure": "transient_less_than_48_hours_or_absent",
      "local_or_systemic_complication": "present_or_absent",
      "exclusion": "no_persistent_organ_failure"
    },
    {
      "outcome_code": "severe",
      "organ_failure": "persistent_more_than_48_hours",
      "organ_systems": "one_or_more",
      "local_or_systemic_complication": "may_be_present_or_absent"
    }
  ],
  "applicability": {
    "intended_use": "Classify a confirmed episode of acute pancreatitis by maximum clinical severity and describe its pancreatic/peripancreatic morphology with standardized terminology.",
    "classification_unit": "one_acute_episode_with_time_from_pain_onset",
    "onset_rule": "Day zero is onset of abdominal pain, not hospital admission, first laboratory result or first scan.",
    "outside_scope": [
      "diagnosis_from_imaging_alone",
      "chronic_pancreatitis_grade",
      "numeric_CT_severity_index",
      "etiology",
      "standalone_treatment_protocol",
      "individual_mortality_prediction"
    ]
  },
  "diagnosis_gate": {
    "rule": "Acute pancreatitis requires at least two of three criteria; do not apply a severity label until this gate is met.",
    "criteria": [
      "acute_persistent_severe_epigastric_pain_often_radiating_to_the_back",
      "serum_lipase_or_amylase_at_least_3_times_the_upper_limit_of_normal",
      "characteristic_findings_on_contrast_enhanced_CT_or_less_commonly_MRI_or_ultrasound"
    ],
    "imaging_not_required_rule": "When characteristic pain and enzyme elevation establish the diagnosis, admission contrast-enhanced CT is usually unnecessary solely to prove pancreatitis.",
    "late_or_equivocal_enzyme_rule": "When pain strongly suggests pancreatitis but enzymes are below three times the upper limit, imaging may be needed to establish the second criterion."
  },
  "organ_failure_gate": {
    "instrument": "modified_Marshall_scoring_system",
    "systems": [
      "respiratory",
      "cardiovascular",
      "renal"
    ],
    "threshold": "score_at_least_2_in_any_one_system",
    "transient": "resolves_within_48_hours",
    "persistent": "continues_for_more_than_48_hours",
    "unresolved_before_48_hours": "potentially_severe_reassess_do_not_finalize_moderately_severe_or_severe",
    "serial_assessment": [
      "presentation",
      "24_hours",
      "48_hours",
      "7_days_or_clinically_relevant_later_timepoint"
    ],
    "multiple_organ_failure": "Record every involved system; the severe code is unchanged but the extent remains clinically important."
  },
  "severity_algorithm": [
    {
      "step": 1,
      "if": "persistent_modified_Marshall_organ_failure_more_than_48_hours",
      "output_code": "severe"
    },
    {
      "step": 2,
      "if": "transient_organ_failure_or_local_complication_or_systemic_complication_without_persistent_organ_failure",
      "output_code": "moderately-severe"
    },
    {
      "step": 3,
      "if": "no_organ_failure_and_no_local_or_systemic_complication",
      "output_code": "mild"
    },
    {
      "step": 4,
      "if": "organ_failure_duration_or_complication_status_not_yet_known",
      "output": "provisional_state_with_required_reassessment"
    }
  ],
  "morphology_axis_separate_from_severity": {
    "interstitial_edematous": "Pancreas enhances without recognizable parenchymal or peripancreatic necrosis; localized or diffuse enlargement and inflammatory change may be present.",
    "necrotizing": "Nonenhancing pancreatic parenchyma and/or nonenhancing heterogeneous peripancreatic tissue represents necrosis.",
    "independence_rule": "Morphologic type and extent do not directly determine the three-grade clinical severity. A patient with necrosis may lack persistent organ failure, and severe disease can be assigned from persistent organ failure regardless of collection type.",
    "early_scan_rule": "Early contrast-enhanced CT can underestimate or fail to show necrosis; retain scan timing and allow later morphology to supersede the early description without rewriting the earlier examination."
  },
  "collection_taxonomy": [
    {
      "name": "acute_peripancreatic_fluid_collection",
      "abbreviation": "APFC",
      "pancreatitis_type": "interstitial_edematous",
      "timing": "usually_less_than_4_weeks",
      "wall": "none",
      "content": "homogeneous_fluid_without_nonliquid_component"
    },
    {
      "name": "pancreatic_pseudocyst",
      "abbreviation": "pseudocyst",
      "pancreatitis_type": "interstitial_edematous",
      "timing": "usually_more_than_4_weeks",
      "wall": "well_defined_encapsulation",
      "content": "homogeneous_fluid_without_nonliquid_component"
    },
    {
      "name": "acute_necrotic_collection",
      "abbreviation": "ANC",
      "pancreatitis_type": "necrotizing",
      "timing": "usually_less_than_4_weeks",
      "wall": "none",
      "content": "heterogeneous_fluid_and_variable_nonliquid_necrotic_material"
    },
    {
      "name": "walled_off_necrosis",
      "abbreviation": "WON",
      "pancreatitis_type": "necrotizing",
      "timing": "usually_at_least_4_weeks",
      "wall": "mature_encapsulation",
      "content": "liquid_and_nonliquid_necrotic_material"
    }
  ],
  "collection_boundary_rules": {
    "clock_and_content_rule": "Both time from symptom onset and presence or absence of necrotic material are required. Do not call every collection after four weeks a pseudocyst.",
    "uncertain_content": "If solid debris cannot be assessed, report indeterminate fluid collection and recommend the modality or follow-up needed to distinguish pseudocyst from WON.",
    "infection": "Gas within an ANC or WON or a compatible clinical course can support infected necrosis, but infection status is reported separately from collection name and severity grade.",
    "deprecated_term": "Do not use pancreatic abscess as a Revised Atlanta collection label."
  },
  "imaging_timing_and_role": {
    "admission": "Reserve CT at presentation for an unclear diagnosis, a concerning alternative diagnosis or another immediate clinical indication.",
    "reassessment": "Current ACG guidance reserves CT or MRI for failure to improve clinically within 48-72 hours or diagnostic uncertainty; use adequately timed contrast-enhanced imaging to define necrosis and complications.",
    "required_metadata": [
      "pain_onset_datetime_or_best_estimate",
      "scan_datetime",
      "phase_and_contrast_adequacy",
      "pancreatic_enhancement",
      "peripancreatic_necrosis",
      "collection_content_wall_and_location",
      "gas_or_other_infection_evidence"
    ]
  },
  "current_care_context_not_encoded_by_grade_alone": {
    "fluid_and_monitoring": "Assess hemodynamics and monitor closely early; lactated Ringer solution and moderately aggressive resuscitation are current general-care context, individualized to comorbidity and response.",
    "antibiotics": "Do not use prophylactic antibiotics for sterile pancreatitis; evaluate and treat when infection is suspected or established.",
    "nutrition": "For mild disease, begin low-fat solid oral feeding within 24-48 hours as tolerated. For moderately severe or severe disease, prefer enteral feeding, including nasogastric delivery when needed, over parenteral nutrition when feasible.",
    "biliary_emergency": "Acute pancreatitis complicated by cholangitis is a separate urgent indication for ERCP, generally within 24 hours.",
    "necrosis_intervention": "In a stable patient with pancreatic necrosis, delay drainage or debridement approximately 4-6 weeks when clinically feasible so the collection can mature.",
    "safety_rule": "Etiology, hemodynamics, infection, symptoms, obstruction and collection maturity drive care. Never emit an intervention solely from mild, moderately severe or severe."
  },
  "risk_and_interpretation": {
    "mild": "Population-level mortality is rare in the consensus description.",
    "moderately_severe": "Morbidity and mortality are higher than mild disease but lower than severe disease; the code does not provide a calibrated individual probability.",
    "severe": "The original consensus cited approximately 36-50 percent mortality for early persistent organ failure in historical cohorts; this is historical context, not a current individual forecast or treatment threshold.",
    "dynamic_rule": "Severity can increase during the episode. Store the worst supported category and its timepoint while preserving earlier provisional assessments."
  },
  "agent_output_contract": [
    "diagnosis_gate_count_and_supporting_features",
    "time_from_pain_onset",
    "modified_Marshall_scores_by_organ_system_and_time",
    "organ_failure_transient_persistent_or_duration_unresolved",
    "exact_severity_code_or_provisional_state",
    "interstitial_edematous_or_necrotizing_morphology_separately",
    "every_collection_named_by_content_wall_and_timing",
    "local_systemic_and_infectious_complications",
    "imaging_timing_and_technical_adequacy",
    "care_context_without_grade_only_commands"
  ],
  "supporting_sources": [
    {
      "role": "international_consensus",
      "citation": "Banks et al. Gut. 2013;62:102-111",
      "doi": "10.1136/gutjnl-2012-302779",
      "pmid": "23100216"
    },
    {
      "role": "current_management_context",
      "citation": "Tenner et al. Am J Gastroenterol. 2024;119:419-437",
      "doi": "10.14309/ajg.0000000000002645",
      "pmid": "38857482"
    }
  ],
  "source_locator": "Banks et al. Revised Atlanta consensus, Gut 2013, DOI 10.1136/gutjnl-2012-302779: Diagnosis of acute pancreatitis, Definition of onset, Definitions of organ failure, Grades of severity, Morphological features and local-complication definitions. Tenner et al. ACG 2024 guideline, DOI 10.14309/ajg.0000000000002645, official guideline highlights for imaging at 48-72 hours, fluids, antibiotics, nutrition, ERCP and delayed necrosis intervention."
}