MAGENT

Emergency · LIVE

CATCH

Apply the Osmond 2010 CATCH derivation and return high, medium, or low risk plus whether CT of the head is indicated from seven caller-assigned findings after pediatric minor head injury.

LIVE $0.005 USDC GET /api/calc/catch

Markdown: /docs/catch.md · Canonical: https://magentlab.com/docs/catch

Not a medical device. Not a diagnosis, dose, or listing recommendation.

What it computes

Apply the Osmond 2010 CATCH derivation and return high, medium, or low risk plus whether CT of the head is indicated from seven caller-assigned findings after pediatric minor head injury.

When to use

When an agent has caller-assigned findings after minor head injury in a child and needs the Osmond 2010 CATCH CT rule, not PECARN, CHALICE, Canadian CT Head, NEXUS, or CATCH-2.

When not to use

  • Not a medical device. Not a diagnosis. magent does not examine the child or read CT.
  • This tool is the Osmond 2010 CATCH derivation only. It is not CATCH-2 (2018) and does not use CATCH-2 refinement items or cutoffs.
  • Not PECARN, not CHALICE, not the Canadian CT Head Rule, and not NEXUS.
  • Derivation enrolled children 0-16 years with minor head injury (GCS 13-15 plus loss of consciousness, amnesia, disorientation, persistent vomiting, or irritability). magent does not take numeric age.
  • The caller assigns all seven findings. Dangerous mechanism is caller-assigned (paper examples: motor vehicle collision, fall from elevation ≥3 ft / ≥91 cm or 5 stairs, fall from bicycle with no helmet). magent does not classify mechanism.

Formula

high if any of gcs_lt_15_at_2h, suspected_open_or_depressed_skull_fracture, worsening_headache, irritability; else medium if any of basal_skull_fracture, large_boggy_scalp_hematoma, dangerous_mechanism; else low; CT indicated if high or medium

Citation

Title
CATCH: a clinical decision rule for the use of computed tomography in children with minor head injury
Authors
Osmond MH, Klassen TP, Wells GA, et al.
Source
CMAJ. 2010;182(4):341-348
DOI
10.1503/cmaj.091421

Worked example

All seven findings absent

Given: basal_skull_fracture=falsedangerous_mechanism=falsegcs_lt_15_at_2h=falseirritability=falselarge_boggy_scalp_hematoma=falsesuspected_open_or_depressed_skull_fracture=falseworsening_headache=false

  1. No high-risk finding (GCS <15 at 2 h, open or depressed skull fracture, worsening headache, irritability)
  2. No medium-risk finding (basal skull fracture, large boggy scalp hematoma, dangerous mechanism)
  3. CATCH low risk; CT is not indicated

GCS <15 at two hours is high risk

Given: basal_skull_fracture=falsedangerous_mechanism=falsegcs_lt_15_at_2h=trueirritability=falselarge_boggy_scalp_hematoma=falsesuspected_open_or_depressed_skull_fracture=falseworsening_headache=false

  1. GCS <15 at two hours is a high-risk finding (need for neurologic intervention)
  2. CATCH high risk; CT is indicated

Dangerous mechanism is medium risk

Given: basal_skull_fracture=falsedangerous_mechanism=truegcs_lt_15_at_2h=falseirritability=falselarge_boggy_scalp_hematoma=falsesuspected_open_or_depressed_skull_fracture=falseworsening_headache=false

  1. No high-risk finding
  2. Dangerous mechanism is a medium-risk finding as assigned by the caller (paper examples: MVC, fall ≥3 ft / ≥91 cm or 5 stairs, unhelmeted bicycle fall)
  3. CATCH medium risk; CT is indicated for brain injury on CT

Also searched as

  • CATCH rule
  • CATCH head CT
  • Osmond CATCH
  • Canadian Assessment of Tomography for Childhood Head injury
  • CATCH 2010
  • pediatric CATCH CT
  • Osmond 2010 CATCH
  • childhood head injury CT rule

Try

Opens the live endpoint. Unpaid browser requests show the paywall; agents should send Accept: application/json.

/api/calc/catch?gcs_lt_15_at_2h=false&suspected_open_or_depressed_skull_fracture=false&worsening_headache=false&irritability=false&basal_skull_fracture=false&large_boggy_scalp_hematoma=false&dangerous_mechanism=false

Full URL: https://api.magentlab.com/api/calc/catch?gcs_lt_15_at_2h=false&suspected_open_or_depressed_skull_fracture=false&worsening_headache=false&irritability=false&basal_skull_fracture=false&large_boggy_scalp_hematoma=false&dangerous_mechanism=false

Call

Expect HTTP 402 until you retry with PAYMENT-SIGNATURE. Incomplete query params return HTTP 400 before any quote or charge. 

curl -i -H "Accept: application/json" "https://api.magentlab.com/api/calc/catch?gcs_lt_15_at_2h=false&suspected_open_or_depressed_skull_fracture=false&worsening_headache=false&irritability=false&basal_skull_fracture=false&large_boggy_scalp_hematoma=false&dangerous_mechanism=false"

Parameters

Name Type Required Description
gcs_lt_15_at_2h boolean required GCS score <15 at two hours after injury. true or false as assigned by the caller. High-risk (need for neurologic intervention). magent does not take a GCS integer.
suspected_open_or_depressed_skull_fracture boolean required Suspected open or depressed skull fracture. true or false as assigned by the caller. High-risk (need for neurologic intervention). magent does not examine the child.
worsening_headache boolean required History of worsening headache. true or false as assigned by the caller. High-risk (need for neurologic intervention).
irritability boolean required Irritability on examination. true or false as assigned by the caller. High-risk (need for neurologic intervention). magent does not examine the child.
basal_skull_fracture boolean required Any sign of basal skull fracture. true or false as assigned by the caller. Medium-risk (brain injury on CT). magent does not examine the child.
large_boggy_scalp_hematoma boolean required Large, boggy hematoma of the scalp. true or false as assigned by the caller. Medium-risk (brain injury on CT). magent does not examine the child.
dangerous_mechanism boolean required Dangerous mechanism of injury as assigned by the caller. true or false. Medium-risk (brain injury on CT). Paper examples: motor vehicle collision, fall from elevation ≥3 ft / ≥91 cm or 5 stairs, fall from bicycle with no helmet. magent does not classify mechanism.

Bulk (POST)

POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement.

POST /api/calc/catch Max 25 unit_amount + extra_item_amount * (n - 1) extra $0.002 PREVIEW

  • 1 to 25 items. Each item uses the same keys as the GET query parameters.
  • POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows.
  • The first invalid item fails the whole request (index in the 400 JSON). You are not charged.
  • HTTP 200 is {count, path, items}. Each items[i] is the GET 200 body for that row.
  • Catalog misses (empty matches, found=false) stay paid 200s inside that slot.
  • x402 resource URL is this path plus n and body_sha256. Browsers that prefer text/html get the same paywall as GET; Pay retries POST with the same items.

Example request (fixture)

{
  "items": [
    {
      "basal_skull_fracture": "false",
      "dangerous_mechanism": "false",
      "gcs_lt_15_at_2h": "false",
      "irritability": "false",
      "large_boggy_scalp_hematoma": "false",
      "suspected_open_or_depressed_skull_fracture": "false",
      "worsening_headache": "false"
    },
    {
      "basal_skull_fracture": "false",
      "dangerous_mechanism": "false",
      "gcs_lt_15_at_2h": "false",
      "irritability": "false",
      "large_boggy_scalp_hematoma": "false",
      "suspected_open_or_depressed_skull_fracture": "false",
      "worsening_headache": "false"
    }
  ]
}

Open bulk paywall →

Opens a two-item fixture on the API host. Unpaid browsers get the same MetaMask paywall as GET; Pay retries POST with those items.

Example 200 (fixture)

{
  "count": 2,
  "path": "/api/calc/catch",
  "items": [
    {
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Osmond MH, Klassen TP, Wells GA, et al.",
        "doi": "10.1503/cmaj.091421",
        "id": "osmond-2010",
        "pmid": "20142371",
        "source": "CMAJ. 2010;182(4):341-348",
        "title": "CATCH: a clinical decision rule for the use of computed tomography in children with minor head injury"
      },
      "formula": "catch",
      "formula_expression": "high if any of gcs_lt_15_at_2h, suspected_open_or_depressed_skull_fracture, worsening_headache, irritability; else medium if any of basal_skull_fracture, large_boggy_scalp_hematoma, dangerous_mechanism; else low; CT indicated if high or medium",
      "criteria": [
        {
          "factor": "gcs_lt_15_at_2h",
          "met": false
        },
        {
          "factor": "suspected_open_or_depressed_skull_fracture",
          "met": false
        },
        {
          "factor": "worsening_headache",
          "met": false
        },
        {
          "factor": "irritability",
          "met": false
        },
        {
          "factor": "basal_skull_fracture",
          "met": false
        },
        {
          "factor": "large_boggy_scalp_hematoma",
          "met": false
        },
        {
          "factor": "dangerous_mechanism",
          "met": false
        }
      ],
      "catch_high_risk": false,
      "catch_low_risk": true,
      "catch_medium_risk": false,
      "ct_indicated": false
    },
    {
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Osmond MH, Klassen TP, Wells GA, et al.",
        "doi": "10.1503/cmaj.091421",
        "id": "osmond-2010",
        "pmid": "20142371",
        "source": "CMAJ. 2010;182(4):341-348",
        "title": "CATCH: a clinical decision rule for the use of computed tomography in children with minor head injury"
      },
      "formula": "catch",
      "formula_expression": "high if any of gcs_lt_15_at_2h, suspected_open_or_depressed_skull_fracture, worsening_headache, irritability; else medium if any of basal_skull_fracture, large_boggy_scalp_hematoma, dangerous_mechanism; else low; CT indicated if high or medium",
      "criteria": [
        {
          "factor": "gcs_lt_15_at_2h",
          "met": false
        },
        {
          "factor": "suspected_open_or_depressed_skull_fracture",
          "met": false
        },
        {
          "factor": "worsening_headache",
          "met": false
        },
        {
          "factor": "irritability",
          "met": false
        },
        {
          "factor": "basal_skull_fracture",
          "met": false
        },
        {
          "factor": "large_boggy_scalp_hematoma",
          "met": false
        },
        {
          "factor": "dangerous_mechanism",
          "met": false
        }
      ],
      "catch_high_risk": false,
      "catch_low_risk": true,
      "catch_medium_risk": false,
      "ct_indicated": false
    }
  ]
}

Response

Field Type Description
formula string catch
formula_expression string Osmond 2010 CATCH high then medium then low CT indication rule
catch_high_risk boolean true when any high-risk finding is present (GCS <15 at 2 h, suspected open or depressed skull fracture, worsening headache, or irritability). Predicts need for neurologic intervention. Not a diagnosis.
catch_medium_risk boolean true when any medium-risk finding is present (basal skull fracture sign, large boggy scalp hematoma, or dangerous mechanism) and no high-risk finding is present. Predicts brain injury on CT. Not a diagnosis.
catch_low_risk boolean true when none of the seven published findings is present
ct_indicated boolean true when catch_high_risk or catch_medium_risk is true (any of the seven findings). Not a diagnosis.
criteria array Per-factor rows with factor and met; met is true when that Osmond 2010 CATCH finding is present
citation object Osmond 2010 CMAJ citation
disclaimer string Not-a-device notice

Example JSON

Machine form of the same example. Frozen fixture. Not a live lookup. 

{
  "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
  "citation": {
    "authors": "Osmond MH, Klassen TP, Wells GA, et al.",
    "doi": "10.1503/cmaj.091421",
    "id": "osmond-2010",
    "pmid": "20142371",
    "source": "CMAJ. 2010;182(4):341-348",
    "title": "CATCH: a clinical decision rule for the use of computed tomography in children with minor head injury"
  },
  "formula": "catch",
  "formula_expression": "high if any of gcs_lt_15_at_2h, suspected_open_or_depressed_skull_fracture, worsening_headache, irritability; else medium if any of basal_skull_fracture, large_boggy_scalp_hematoma, dangerous_mechanism; else low; CT indicated if high or medium",
  "criteria": [
    {
      "factor": "gcs_lt_15_at_2h",
      "met": false
    },
    {
      "factor": "suspected_open_or_depressed_skull_fracture",
      "met": false
    },
    {
      "factor": "worsening_headache",
      "met": false
    },
    {
      "factor": "irritability",
      "met": false
    },
    {
      "factor": "basal_skull_fracture",
      "met": false
    },
    {
      "factor": "large_boggy_scalp_hematoma",
      "met": false
    },
    {
      "factor": "dangerous_mechanism",
      "met": false
    }
  ],
  "catch_high_risk": false,
  "catch_low_risk": true,
  "catch_medium_risk": false,
  "ct_indicated": false
}

Client errors (HTTP 400)

Invalid params return 400 without charge. Shared HTTP 402 and 503 meanings: Payments.

HTTP Code When
400 invalid_flag boolean clinical flags must be true or false Returned before settlement; you are not charged.
400 invalid_items POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
400 invalid_item_count items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
400 invalid_item each items entry must be a JSON object Returned before settlement; you are not charged.

Related tools

  • PECARN pediatric head CT — Apply the Kuppermann 2009 PECARN prediction trees and return high, intermediate, or low risk of clinically important brain injury from caller-assigned findings after pediatric head trauma.
  • CHALICE — Apply the Dunning 2006 CHALICE rule and return whether CT is required from caller-assigned history, examination, and mechanism findings after head injury in a child younger than 16.
  • Canadian CT Head Rule — Apply the Stiell 2001 Canadian CT Head Rule and return whether CT is indicated from caller-assigned high-risk and medium-risk findings after minor blunt head injury.
  • New Orleans Head CT Rule — Apply the Haydel 2000 New Orleans Head CT Rule and return whether CT is indicated from age and six caller-assigned findings after minor head injury.

Payment

Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, invalid params return HTTP 400 JSON before settlement. magent does not charge. Fix the params, then request a new 402 quote for that complete URL. Catalog misses (empty matches, found=false) are valid paid 200s. Unpaid valid requests return HTTP 402 with a base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote: retry the same PAYMENT-SIGNATURE. Full handshake and shared payment errors: Payments. Stdio MCP: /docs/mcp.

Guarantees

  • HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged.
  • exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. Uncertain or failed settlement fails closed (HTTP 503). Retry the same PAYMENT-SIGNATURE.
  • HTTP 402 is unpaid only. Do not sign a second authorization because of a 503.
  • Execution is timeout-bounded and concurrency-capped.
  • Calculator inputs are stored encrypted for allowlisted operators (Magent Console). They are not in public logs, SSH lookups, catalog, or rollups. Request logs store path without query.