# Rome IV cyclic vomiting

Rome IV CVS

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/rome_iv_cvs`
HTML: https://magentlab.com/docs/rome-iv-cvs
Markdown: https://magentlab.com/docs/rome-iv-cvs.md

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

## What it computes

Apply the Stanghellini 2016 Rome IV adult cyclic vomiting syndrome B3b diagnostic criteria and return whether the published CVS box holds (rome_iv_cvs) plus the supportive migraine_history flag.

## When to use

When an agent already has the eight caller-assigned Stanghellini 2016 Rome IV adult CVS B3b flags and needs whether the published CVS box holds. magent does not examine the patient.

## When not to use

- Not a medical device.
- Not a diagnosis. magent does not diagnose cyclic vomiting syndrome.
- The caller assigns the eight flags. magent does not examine the patient.
- This tool is Stanghellini 2016 Rome IV adult cyclic vomiting syndrome B3b only. Migraine history is supportive and not required for rome_iv_cvs. Not cannabinoid hyperemesis syndrome. Not pediatric or child Rome IV CVS. Not Rome IV IBS (Mearin 2016).

## Formula

```
rome_iv_cvs iff stereotypical_episodes_acute_lt_1_week and at_least_three_episodes_prior_year and at_least_two_episodes_past_6_months and episodes_at_least_1_week_apart and absence_of_vomiting_between_episodes and fulfilled_last_3_months and onset_at_least_6_months; migraine_history is supportive and not required (Stanghellini 2016 Rome IV adult cyclic vomiting syndrome B3b)
```

## Citation

[Gastroduodenal Disorders](https://doi.org/10.1053/j.gastro.2016.02.011)
Stanghellini V, Chan FKL, Hasler WL, Malagelada JR, Suzuki H, Tack J, Talley NJ
Gastroenterology. 2016;150(6):1380-1392
DOI: [10.1053/j.gastro.2016.02.011](https://doi.org/10.1053/j.gastro.2016.02.011)

## Worked example

### Seven required flags and migraine history

Given: `absence_of_vomiting_between_episodes=true, at_least_three_episodes_prior_year=true, at_least_two_episodes_past_6_months=true, episodes_at_least_1_week_apart=true, fulfilled_last_3_months=true, migraine_history=true, onset_at_least_6_months=true, stereotypical_episodes_acute_lt_1_week=true`

1. Stereotypical episodes of vomiting with acute onset and duration under 1 week is true
2. At least 3 discrete episodes in the prior year, 2 in the past 6 months, and episodes at least 1 week apart are true
3. Absence of vomiting between episodes is true
4. Criteria fulfilled for the last 3 months and onset at least 6 months prior are true
5. Migraine history is true (supportive, not required)
6. rome_iv_cvs is true


### Seven required flags without migraine history

Given: `absence_of_vomiting_between_episodes=true, at_least_three_episodes_prior_year=true, at_least_two_episodes_past_6_months=true, episodes_at_least_1_week_apart=true, fulfilled_last_3_months=true, migraine_history=false, onset_at_least_6_months=true, stereotypical_episodes_acute_lt_1_week=true`

1. All seven required flags hold
2. Migraine history is false
3. rome_iv_cvs is true because migraine_history is supportive and not required


## Also searched as

- Rome IV CVS
- Rome IV cyclic vomiting
- cyclic vomiting syndrome
- Stanghellini 2016 CVS
- adult cyclic vomiting Rome IV
- Rome IV B3b
- cyclic vomiting diagnostic criteria
- Rome IV gastroduodenal CVS

## Parameters

- `stereotypical_episodes_acute_lt_1_week` (boolean, required): Stereotypical episodes of vomiting regarding onset (acute) and duration (<1 week) (Stanghellini 2016 Rome IV adult B3b). true or false as assigned by the caller. magent does not examine the patient.
- `at_least_three_episodes_prior_year` (boolean, required): 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` (boolean, required): 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 history.
- `episodes_at_least_1_week_apart` (boolean, required): 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.
- `absence_of_vomiting_between_episodes` (boolean, required): Absence of vomiting between episodes; milder symptoms between cycles are allowed (Stanghellini 2016). true or false as assigned by the caller. magent does not examine the patient.
- `fulfilled_last_3_months` (boolean, required): 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` (boolean, required): 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.
- `migraine_history` (boolean, required): 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.

## 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.

Method: `POST /api/calc/rome_iv_cvs`
Max items: 25
Price: unit_amount + extra_item_amount * (n - 1) (unit 5000 atomic, extra 2000 atomic)
Status: 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:

```json
{
  "items": [
    {
      "absence_of_vomiting_between_episodes": "true",
      "at_least_three_episodes_prior_year": "true",
      "at_least_two_episodes_past_6_months": "true",
      "episodes_at_least_1_week_apart": "true",
      "fulfilled_last_3_months": "true",
      "migraine_history": "true",
      "onset_at_least_6_months": "true",
      "stereotypical_episodes_acute_lt_1_week": "true"
    },
    {
      "absence_of_vomiting_between_episodes": "true",
      "at_least_three_episodes_prior_year": "true",
      "at_least_two_episodes_past_6_months": "true",
      "episodes_at_least_1_week_apart": "true",
      "fulfilled_last_3_months": "true",
      "migraine_history": "true",
      "onset_at_least_6_months": "true",
      "stereotypical_episodes_acute_lt_1_week": "true"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/rome-iv-cvs

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/rome_iv_cvs",
  "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": "Stanghellini V, Chan FKL, Hasler WL, Malagelada JR, Suzuki H, Tack J, Talley NJ",
        "doi": "10.1053/j.gastro.2016.02.011",
        "id": "stanghellini-2016",
        "pmid": "27147122",
        "source": "Gastroenterology. 2016;150(6):1380-1392",
        "title": "Gastroduodenal Disorders"
      },
      "formula": "rome_iv_cvs",
      "formula_expression": "rome_iv_cvs iff stereotypical_episodes_acute_lt_1_week and at_least_three_episodes_prior_year and at_least_two_episodes_past_6_months and episodes_at_least_1_week_apart and absence_of_vomiting_between_episodes and fulfilled_last_3_months and onset_at_least_6_months; migraine_history is supportive and not required (Stanghellini 2016 Rome IV adult cyclic vomiting syndrome B3b)",
      "criteria": [
        {
          "factor": "stereotypical_episodes_acute_lt_1_week",
          "met": true
        },
        {
          "factor": "at_least_three_episodes_prior_year",
          "met": true
        },
        {
          "factor": "at_least_two_episodes_past_6_months",
          "met": true
        },
        {
          "factor": "episodes_at_least_1_week_apart",
          "met": true
        },
        {
          "factor": "absence_of_vomiting_between_episodes",
          "met": true
        },
        {
          "factor": "fulfilled_last_3_months",
          "met": true
        },
        {
          "factor": "onset_at_least_6_months",
          "met": true
        },
        {
          "factor": "migraine_history",
          "met": true
        }
      ],
      "migraine_history": true,
      "rome_iv_cvs": true
    },
    {
      "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": "Stanghellini V, Chan FKL, Hasler WL, Malagelada JR, Suzuki H, Tack J, Talley NJ",
        "doi": "10.1053/j.gastro.2016.02.011",
        "id": "stanghellini-2016",
        "pmid": "27147122",
        "source": "Gastroenterology. 2016;150(6):1380-1392",
        "title": "Gastroduodenal Disorders"
      },
      "formula": "rome_iv_cvs",
      "formula_expression": "rome_iv_cvs iff stereotypical_episodes_acute_lt_1_week and at_least_three_episodes_prior_year and at_least_two_episodes_past_6_months and episodes_at_least_1_week_apart and absence_of_vomiting_between_episodes and fulfilled_last_3_months and onset_at_least_6_months; migraine_history is supportive and not required (Stanghellini 2016 Rome IV adult cyclic vomiting syndrome B3b)",
      "criteria": [
        {
          "factor": "stereotypical_episodes_acute_lt_1_week",
          "met": true
        },
        {
          "factor": "at_least_three_episodes_prior_year",
          "met": true
        },
        {
          "factor": "at_least_two_episodes_past_6_months",
          "met": true
        },
        {
          "factor": "episodes_at_least_1_week_apart",
          "met": true
        },
        {
          "factor": "absence_of_vomiting_between_episodes",
          "met": true
        },
        {
          "factor": "fulfilled_last_3_months",
          "met": true
        },
        {
          "factor": "onset_at_least_6_months",
          "met": true
        },
        {
          "factor": "migraine_history",
          "met": true
        }
      ],
      "migraine_history": true,
      "rome_iv_cvs": true
    }
  ]
}
```

## Response fields

- `formula` (string): rome_iv_cvs
- `formula_expression` (string): Stanghellini 2016 Rome IV adult CVS B3b: stereotypical acute episodes <1 week, ≥3 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
- `migraine_history` (boolean): Caller-assigned supportive migraine (personal or family) flag. Reported separately; not required for rome_iv_cvs.
- `rome_iv_cvs` (boolean): true only when all seven required flags hold. migraine_history is not required. Not a diagnosis.
- `criteria` (array): Per-factor rows with factor and met for the seven required flags plus supportive migraine_history
- `citation` (object): Stanghellini 2016 Gastroenterology citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "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": "Stanghellini V, Chan FKL, Hasler WL, Malagelada JR, Suzuki H, Tack J, Talley NJ",
    "doi": "10.1053/j.gastro.2016.02.011",
    "id": "stanghellini-2016",
    "pmid": "27147122",
    "source": "Gastroenterology. 2016;150(6):1380-1392",
    "title": "Gastroduodenal Disorders"
  },
  "formula": "rome_iv_cvs",
  "formula_expression": "rome_iv_cvs iff stereotypical_episodes_acute_lt_1_week and at_least_three_episodes_prior_year and at_least_two_episodes_past_6_months and episodes_at_least_1_week_apart and absence_of_vomiting_between_episodes and fulfilled_last_3_months and onset_at_least_6_months; migraine_history is supportive and not required (Stanghellini 2016 Rome IV adult cyclic vomiting syndrome B3b)",
  "criteria": [
    {
      "factor": "stereotypical_episodes_acute_lt_1_week",
      "met": true
    },
    {
      "factor": "at_least_three_episodes_prior_year",
      "met": true
    },
    {
      "factor": "at_least_two_episodes_past_6_months",
      "met": true
    },
    {
      "factor": "episodes_at_least_1_week_apart",
      "met": true
    },
    {
      "factor": "absence_of_vomiting_between_episodes",
      "met": true
    },
    {
      "factor": "fulfilled_last_3_months",
      "met": true
    },
    {
      "factor": "onset_at_least_6_months",
      "met": true
    },
    {
      "factor": "migraine_history",
      "met": true
    }
  ],
  "migraine_history": true,
  "rome_iv_cvs": true
}
```

## Errors

- HTTP 400 `invalid_rome_iv_cvs`: Rome IV cyclic vomiting needs the eight Stanghellini 2016 adult B3b flags. Returned before settlement; you are not charged.
- HTTP 400 `invalid_flag`: boolean clinical flags must be true or false Returned before settlement; you are not charged.
- HTTP 400 `invalid_items`: POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
- HTTP 400 `invalid_item_count`: items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
- HTTP 400 `invalid_item`: each items entry must be a JSON object Returned before settlement; you are not charged.

Shared HTTP 402 and 503: https://magentlab.com/docs/payments

## Related tools

- [Rome IV CHS](https://magentlab.com/docs/rome-iv-chs) — Apply the Stanghellini 2016 Rome IV cannabinoid hyperemesis syndrome diagnostic criteria and return whether the published CHS box holds (rome_iv_chs) plus the supportive pathologic_bathing flag.
- [Rome IV FD](https://magentlab.com/docs/rome-iv-fd) — Apply the Stanghellini 2016 Rome IV B1 functional dyspepsia criteria and return whether PDS (B1a), EPS (B1b), and the published FD box hold (rome_iv_fd).

## 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.

- GET the tool with Accept: application/json (do not send Accept: text/html unless you want the human paywall).
- HTTP 402 means you have not paid. Decode the base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote.
- Sign accepts[0] (exact, EIP-3009) with validBefore = now + maxTimeoutSeconds (600 seconds), or accepts[1] (batch-settlement deposit/voucher) on product GET. Ping and POST {items} stay exact. Magent retries transient facilitator 429/5xx before answering.
- Retry the same URL with PAYMENT-SIGNATURE (base64 JSON of accepted and payload). Magent attaches canonical extensions.bazaar on CDP verify/settle; echoing 402 bazaar is optional.
- Success is HTTP 200 JSON plus PAYMENT-RESPONSE. exact settles before the tool. batch-settlement verifies (and deposit-settles) before the tool and commits the charge after HTTP 2xx. HTTP 503: retry the same PAYMENT-SIGNATURE. Mint a new exact nonce only after a new HTTP 402.

- offered `exact` on eip155:8453: Fixed-price USDC on Base. The buyer authorizes the advertised amount (EIP-3009). magent settles before the tool runs (paymentFlow upfront). extra.assetTransferMethod=eip3009 extra.paymentFlow=upfront.
- offered `batch-settlement` on eip155:8453: Payment-channel vouchers claimed later in batches. Exact stays accepts[0]. Same-path POST {items} is still exact. extra.assetTransferMethod=eip3009 extra.paymentFlow=authorization.

- not offered `upto`: Not offered. Usage-based: buyer authorizes a ceiling, seller settles the actual amount after work. Reserved for a future metered tool. Not for current calculators or code search.

Same-path POST {items} is still scheme exact: one EIP-3009 authorization for GET unit plus $0.002 per extra item. That is not x402 batch-settlement (payment channels / vouchers).

Shared HTTP 402 and 503 table: https://magentlab.com/docs/payments

Stdio MCP (one process per host): https://magentlab.com/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. HTTP 402 never includes the tool JSON.
- 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.