# Pediatric NEXUS II Head CT Decision Rule (Gupta 2018)

> Pediatric NEXUS II Head CT Decision Rule (Gupta 2018) is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).

Applies the Pediatric NEXUS II (Gupta 2018) clinical decision rule to determine if a child aged 0–17 is low-risk for clinically significant head injury based on seven binary criteria.

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/pediatric_nexus_ii
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pediatric-nexus-ii-head-ct-decision-rule-gupta-2018-481ea9e6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_TQDxkwOVx6mGO7EdHzLf5

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability pediatric-nexus-ii-head-ct-decision-rule-gupta-2018-481ea9e6
```

Example prompt: Run the Pediatric NEXUS II rule for a 9-year-old with a head injury: no skull fracture, no scalp hematoma, no neurologic deficit, alertness is normal, behavior is normal, no vomiting, and no coagulopathy — is the child low risk?

## When to prefer this

Use this endpoint when you need to apply the specific Gupta 2018 Pediatric NEXUS II clinical decision rule for children aged 0–17 presenting with head trauma. Choose this over PECARN, CATCH, or CHALICE when your workflow specifically requires NEXUS II pediatric criteria. Do not use for adults, for C-spine clearance (Hoffman 2000 NEXUS), or when a diagnosis or CT order is required — this is purely a rule-based risk classification tool.

## Known failure modes

- Age outside 0–17 range returns a rejection error (age 18 is explicitly rejected)
- Missing any of the seven required boolean query parameters returns a validation error
- Misclassification risk if caller-assigned clinical flags are inaccurate — the API does not examine the patient
- Rule does not apply to adults; adult NEXUS Head CT (age ≥65 criterion) is not supported here

## How this service works

Pediatric NEXUS II (Gupta 2018). Low-risk iff all seven flags are false: skull fracture, scalp hematoma, neurologic deficit, altered alertness, abnormal behavior, persistent vomiting, and coagulopathy. Age 0-17 is required but is not a criterion; adult NEXUS Head CT age >= 65 is dropped. Not a diagnosis, not a CT order, not Mower 2017 adult NEXUS Head CT, not PECARN, CATCH, or CHALICE, and not Hoffman 2000 NEXUS C-spine. magent does not examine the patient.

## Output

Returns a low_risk boolean (true if all seven criteria flags are false, meaning the patient may not require CT; false if any criterion is present), along with the individual flag values passed in and a summary of the rule applied. Does not include a CT recommendation or diagnosis.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "headers": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    },
    "queryParams": {
     "type": "object",
     "required": [
      "age",
      "skull_fracture",
      "scalp_hematoma",
      "neurologic_deficit",
      "altered_alertness",
      "abnormal_behavior",
      "persistent_vomiting",
      "coagulopathy"
     ],
     "properties": {
      "age": {
       "type": "integer",
       "description": "Age in years (integer 0-17). Required to match the Gupta 2018 pediatric population but is not a score criterion. Age 18 is rejected. Adult NEXUS Head CT age ≥ 65 is dropped."
      },
      "coagulopathy": {
       "type": "boolean",
       "description": "Coagulopathy as assigned by the caller. true means coagulopathy is present and low_risk is false. true or false. magent does not interpret a coagulation assay."
      },
      "scalp_hematoma": {
       "type": "boolean",
       "description": "Scalp hematoma as assigned by the caller. true means a scalp hematoma is present and low_risk is false. true or false. magent does not examine the scalp."
      },
      "skull_fracture": {
       "type": "boolean",
       "description": "Evidence of skull fracture as assigned by the caller. true means a skull-fracture finding is present and low_risk is false. true or false. magent does not examine the patient or read a radiograph."
      },
      "abnormal_behavior": {
       "type": "boolean",
       "description": "Abnormal behavior as assigned by the caller. true means abnormal behavior is present and low_risk is false. true or false. magent does not examine the patient."
      },
      "altered_alertness": {
       "type": "boolean",
       "description": "Altered level of alertness as assigned by the caller. true means alertness is altered and low_risk is false. true or false. magent does not assign GCS."
      },
      "neurologic_deficit": {
       "type": "boolean",
       "description": "Neurologic deficit (neurosurgical deficits) as assigned by the caller. true means a deficit is present and low_risk is false.
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pediatric-nexus-ii-head-ct-decision-rule-gupta-2018-481ea9e6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.magentlab.com](https://www.zero.xyz/host/api.magentlab.com/llms.txt)