# Rome IV Cyclic Vomiting Syndrome (CVS) Criteria Calculator

> Rome IV Cyclic Vomiting Syndrome (CVS) Criteria Calculator 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).

Evaluates eight boolean clinical flags against the Stanghellini 2016 Rome IV B3b criteria to determine whether a patient meets the diagnostic criteria for adult cyclic vomiting syndrome (CVS).

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/rome_iv_cvs
- 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/rome-iv-cyclic-vomiting-syndrome-cvs-criteria-calculator-7fcecd72
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_pbOqw-HIycbsJ0bfbCUwi

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 rome-iv-cyclic-vomiting-syndrome-cvs-criteria-calculator-7fcecd72
```

Example prompt: Can you check whether this patient meets Rome IV adult CVS criteria? They have stereotypical acute episodes lasting under a week, 4 episodes in the past year, 2 episodes in the past 6 months that are at least a week apart, no vomiting between episodes, criteria met for the last 3 months, onset more than 6 months ago, and a personal history of migraine.

## When to prefer this

Use this endpoint when you need a fast, rule-based computation of whether a set of pre-assessed clinical boolean flags satisfies the Stanghellini 2016 Rome IV B3b adult CVS criteria. It is not a substitute for clinical judgment, history-taking, or differential diagnosis. Prefer this over manual criteria lookup when building clinical decision support tools, EMR integrations, or research screening pipelines that require consistent, auditable rule application.

## Known failure modes

- Missing required boolean query parameters returns a validation error
- Misassignment of flags by caller leads to incorrect result — the endpoint trusts all inputs as provided
- Pediatric CVS, CHS (cannabinoid hyperemesis syndrome), and Rome IV IBS are explicitly out of scope
- Network errors or payment failures (x402) result in no response

## How this service works

Stanghellini 2016 Rome IV adult CVS B3b. rome_iv_cvs is true iff stereotypical acute vomiting episodes lasting <1 week, ≥3 discrete episodes in the prior year and 2 in 6 months at least 1 week apart, absence of vomiting between episodes, last-3-months criteria, and 6-month onset. migraine_history is supportive and not required. Caller assigns eight flags. magent does not examine the patient. Not a diagnosis, not CHS, not pediatric CVS, not Rome IV IBS.

## Output

Returns a boolean field rome_iv_cvs indicating whether all required Rome IV B3b CVS criteria are satisfied (true) or not (false), along with the migraine_history supportive criterion. Does not provide a diagnosis; caller is responsible for clinical interpretation.

## 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": [
      "stereotypical_episodes_acute_lt_1_week",
      "at_least_three_episodes_prior_year",
      "at_least_two_episodes_past_6_months",
      "episodes_at_least_1_week_apart",
      "absence_of_vomiting_between_episodes",
      "fulfilled_last_3_months",
      "onset_at_least_6_months",
      "migraine_history"
     ],
     "properties": {
      "migraine_history": {
       "type": "boolean",
       "description": "Personal history of migraine or family history of migraine, a supportive criterion that is not required for rome_iv_cvs (Stanghellini 2016). true or false as assigned by the caller. magent does not take a history."
      },
      "fulfilled_last_3_months": {
       "type": "boolean",
       "description": "Criteria fulfilled for the last 3 months, as assigned (Stanghellini 2016). true or false as assigned by the caller. magent does not take a history."
      },
      "onset_at_least_6_months": {
       "type": "boolean",
       "description": "Symptom onset at least 6 months prior to diagnosis, as assigned (Stanghellini 2016). true or false as assigned by the caller. magent does not take a history."
      },
      "episodes_at_least_1_week_apart": {
       "type": "boolean",
       "description": "Discrete vomiting episodes occurring at least 1 week apart, as assigned (Stanghellini 2016). true or false as assigned by the caller. magent does not take a history."
      },
      "at_least_three_episodes_prior_year": {
       "type": "boolean",
       "description": "At least 3 discrete vomiting episodes in the prior year, as assigned (Stanghellini 2016). true or false as assigned by the caller. magent does not take a history."
      },
      "at_least_two_episodes_past_6_months": {
       "type": "boolean",
       "description": "At least 2 discrete vomiting episodes in the past 6 months, as assigned (Stanghellini 2016). true or false as assigned by the caller. magent does not take a 
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/rome-iv-cyclic-vomiting-syndrome-cvs-criteria-calculator-7fcecd72/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)