Cambridge classification of chronic pancreatitis morphology

{
  "categories": [
    {
      "outcome_code": "normal",
      "official_grade": "0",
      "label": "normal",
      "role": "canonical_Cambridge_grade"
    },
    {
      "outcome_code": "equivocal",
      "official_grade": "I",
      "label": "equivocal",
      "role": "canonical_Cambridge_grade"
    },
    {
      "outcome_code": "mild",
      "official_grade": "II",
      "label": "mild",
      "role": "canonical_Cambridge_grade"
    },
    {
      "outcome_code": "moderate",
      "official_grade": "III",
      "label": "moderate",
      "role": "canonical_Cambridge_grade"
    },
    {
      "outcome_code": "marked",
      "official_grade": "IV",
      "label": "marked_or_severe",
      "role": "canonical_Cambridge_grade"
    },
    {
      "outcome_code": "mild-or-moderate",
      "official_grade": "II_or_III_unresolved",
      "label": "mild_versus_moderate_not_separable",
      "role": "operational_uncertainty_state_not_an_extra_official_grade"
    }
  ],
  "applicability": {
    "use_for": "Morphologic characterization of suspected or established chronic pancreatitis after the imaging modality and visible ductal or parenchymal features are known.",
    "classification_unit": "one_pancreas_at_one_examination",
    "required_inputs": [
      "modality",
      "technical_adequacy",
      "abnormal_side_branch_count_when_ductography_is_used",
      "main_pancreatic_duct_status",
      "cross_sectional_feature_count",
      "marked_feature_presence"
    ],
    "outside_scope": [
      "acute_pancreatitis_severity",
      "pancreatic_neoplasm_staging",
      "etiologic_classification",
      "exocrine_or_endocrine_function_stage",
      "treatment_selection_from_morphology_alone"
    ]
  },
  "modality_and_quality_gate": {
    "original_scope": "The Cambridge morphology grades were developed around ERCP duct changes. ERCP is now generally reserved for therapeutic intent rather than used solely to diagnose chronic pancreatitis.",
    "ductal_branch": "Use ERCP or adequately visualized MRCP ductal findings for the side-branch and main-duct rules; record whether secretin was used because it may improve branch depiction.",
    "cross_sectional_branch": "Use the APA adaptation for CT, conventional MRI or transabdominal ultrasound, retaining the modality because the feature sets and sensitivity differ.",
    "inadequacy_rule": "If the main duct or side branches are not sufficiently visualized, do not treat an unobserved ductal abnormality as absent. Return the supported cross-sectional state and state the visualization limit.",
    "early_disease_guard": "Normal CT, MRI or MRCP morphology does not exclude early chronic pancreatitis when clinical suspicion remains high; early disease may require a stepwise clinical, functional or endoscopic evaluation."
  },
  "ductal_ERCP_or_MRCP_algorithm": [
    {
      "if": "no_abnormal_ductal_signs",
      "output_code": "normal",
      "official_grade": "0"
    },
    {
      "if": "one_or_two_abnormal_side_branches_and_no_higher_grade_rule",
      "output_code": "equivocal",
      "official_grade": "I"
    },
    {
      "if": "three_or_more_abnormal_side_branches_without_the_complete_moderate_or_marked_pattern",
      "output_code": "mild",
      "official_grade": "II"
    },
    {
      "if": "more_than_three_abnormal_side_branches_and_abnormal_main_pancreatic_duct_without_a_marked_feature",
      "output_code": "moderate",
      "official_grade": "III"
    },
    {
      "if": "moderate_ductal_changes_plus_at_least_one_marked_feature",
      "output_code": "marked",
      "official_grade": "IV"
    }
  ],
  "ductal_marked_features": [
    "large_cavity_greater_than_10_mm",
    "intraductal_filling_defect_or_calculus",
    "main_duct_obstruction_or_stricture",
    "severe_main_duct_irregularity_or_dilatation"
  ],
  "cross_sectional_CT_MRI_US_algorithm": {
    "base_feature_set": [
      "main_pancreatic_duct_2_to_4_mm",
      "slight_gland_enlargement",
      "heterogeneous_parenchyma",
      "small_cavity_under_10_mm",
      "irregular_ducts",
      "focal_pancreatitis",
      "increased_echogenicity_of_main_duct_wall_on_ultrasound",
      "irregular_head_or_body_contour"
    ],
    "no_feature": {
      "output_code": "normal",
      "official_grade": "0"
    },
    "exactly_one_base_feature": {
      "output_code": "equivocal",
      "official_grade": "I"
    },
    "two_or_more_base_features_without_marked_feature": {
      "output_code": "mild-or-moderate",
      "official_grade": "II_or_III_unresolved",
      "reason": "APA Table 6 assigns the feature set to mild morphology but explicitly states that CT/MRI cannot distinguish moderate from mild. Without the ductal branch, forcing II or III creates false precision."
    },
    "marked_changes_plus_one_or_more_marked_features": {
      "output_code": "marked",
      "official_grade": "IV"
    },
    "counting_rule": "Count each demonstrated feature once, preserve its location and modality, and do not convert one complex observation into multiple independent features solely to cross a threshold."
  },
  "cross_sectional_marked_features": [
    "large_cavity_greater_than_10_mm",
    "substantial_or_gross_gland_enlargement",
    "intraductal_filling_defect_or_calculus",
    "duct_obstruction_or_stricture",
    "gross_duct_irregularity"
  ],
  "main_duct_and_feature_normalization": {
    "two_to_four_mm_rule": "The APA cross-sectional table uses a 2-4 mm main pancreatic duct as one base feature; record the measured segment and do not apply the number without anatomy, age and modality context.",
    "abnormal_main_duct_for_grade_III": "Document which ductal abnormality is present, such as dilatation, irregularity or stricture; a bare word such as abnormal is insufficient for an agent-facing result.",
    "cavity_rule": "Separate side-branch ectasia or small cavities under 10 mm from a large cavity over 10 mm, and do not assume every pancreatic cyst is a chronic-pancreatitis cavity.",
    "calcification_rule": "Intraductal calculus or filling defect is a marked feature in the adaptation, but its location and alternative causes still require confirmation."
  },
  "diagnostic_evidence_context_from_APA": {
    "normal_or_equivocal": "Normal or equivocal morphology alone is insufficient evidence for a chronic-pancreatitis diagnosis.",
    "mild": "Mild morphology supports probable chronic pancreatitis only when combined with a suggestive history or abnormal imaging context and abnormal pancreatic physiology in the APA evidence framework.",
    "moderate_or_marked": "Moderate or marked ductal and parenchymal morphology is listed as definitive imaging evidence, while a credible mimicker such as pancreatic cancer must still be excluded.",
    "unresolved_II_III": "The operational mild-or-moderate state does not silently inherit definitive status; resolve the ductal branch or integrate the full clinical and physiologic evidence before labeling certainty."
  },
  "stepwise_clinical_context": {
    "sequence": [
      "survey_history_risk_factors_and_prior_pancreatitis",
      "pancreas_protocol_CT_or_MRI_MRCP",
      "specialist_EUS_when_equivocal",
      "pancreatic_function_testing_when_needed",
      "ERCP_with_therapeutic_intent"
    ],
    "least_invasive_rule": "Proceed from less invasive to more invasive testing and maximize specificity before assigning a chronic irreversible disease label.",
    "physiology_rule": "Report exocrine and endocrine function separately. Cambridge morphology does not determine secretory, exocrine or endocrine stage."
  },
  "differential_and_complication_checks": [
    "Exclude pancreatic ductal adenocarcinoma when there is an abrupt or long stricture, upstream atrophy, a mass, vascular involvement, unexplained weight loss or another discordant feature.",
    "Consider main-duct or mixed-type IPMN when duct dilatation, side-branch cysts or mucin cannot be confidently attributed to chronic pancreatitis.",
    "Consider autoimmune, obstructive, hereditary and recurrent-acute-pancreatitis causes rather than treating the morphology grade as an etiology.",
    "Report pseudocyst or other collection, biliary or duodenal obstruction, splenic-vein thrombosis, vascular complication and acute-on-chronic inflammation separately."
  ],
  "management_and_risk_context": {
    "management_rule": "The Cambridge grade does not prescribe analgesia, enzymes, endoscopy, surgery or surveillance. It structures morphology and diagnostic certainty; care depends on pain, obstruction, stones, collections, nutrition, exocrine and endocrine function, etiology and cancer concern.",
    "risk_rule": "Higher grades indicate greater morphologic abnormality but do not provide per-grade probabilities for pain, insufficiency, cancer, hospitalization or intervention.",
    "safety_rule": "Do not infer absence of physiologic impairment from a low grade or quantify complication risk from the ordinal label alone."
  },
  "output_contract": [
    "modality_and_protocol_including_secretin_status_when_relevant",
    "technical_adequacy_and_duct_visualization",
    "abnormal_side_branch_count",
    "main_pancreatic_duct_measurement_and_morphology",
    "cross_sectional_base_features_with_locations",
    "marked_features_and_complications",
    "Cambridge_word_label_and_official_grade_0_to_IV_or_mild_or_moderate_operational_uncertainty",
    "APA_diagnostic_evidence_context",
    "neoplasm_or_other_mimicker_warning",
    "physiology_and_etiology_reported_separately"
  ],
  "missing_input_behavior": [
    "If modality is unknown, do not apply a threshold because the ductal and cross-sectional branches are not interchangeable.",
    "If side branches are not visualized, do not infer a normal, equivocal, mild or moderate ductal grade from their apparent absence.",
    "If CT, MRI or ultrasound shows at least two base features but no adequate ductal branch, return mild-or-moderate rather than forcing II or III.",
    "If a marked feature is suspected but size, duct relationship or alternative diagnosis is unresolved, report suspected advanced morphology and request characterization rather than automatically assigning IV.",
    "If cancer or another obstructive cause remains credible, do not finalize chronic pancreatitis as the sole explanation from the Cambridge score."
  ],
  "interpretation_limits": [
    "The original classification is primarily ductographic; its translation to CT, MRI and ultrasound is an adaptation with limited intermediate-grade separation.",
    "A morphology grade is not an etiology, pain scale, functional stage, cancer-risk calculator or treatment algorithm.",
    "Normal morphology cannot exclude early disease, and advanced morphology cannot by itself exclude a superimposed neoplasm."
  ],
  "source_locator": "Sarner and Cotton, Gut 1984;25:756-759, PMID 6735257, DOI 10.1136/gut.25.7.756, Cambridge consensus and original ductographic framework; Conwell et al., Pancreas 2014;43:1143-1162, PMID 25333398, DOI 10.1097/MPA.0000000000000237, Evidence-Based Report, Tables 5-8 and STEP-wise algorithm; Tirkes et al., Magn Reson Imaging Clin N Am 2018;26:451-467, PMC6214211, Table 3 and imaging limitations."
}