# Rome IV functional diarrhea

Rome IV Diarrhea

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

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

## What it computes

Apply the Mearin 2016 Rome IV C3 functional diarrhea criteria and return whether the published C3 box holds (rome_iv_diarrhea).

## When to use

When an agent already has the three caller-assigned Rome IV C3 flags as in Mearin 2016 and needs whether the published functional diarrhea box holds. magent does not examine the patient.

## When not to use

- Not a medical device.
- Not a diagnosis. magent does not diagnose functional diarrhea.
- The caller assigns the three flags. magent does not examine the patient.
- This tool is adult Rome IV C3 functional diarrhea only. Not child G5, not IBS-D, not Rome IV IBS (Mearin 2016 IBS box), not Manning, and not functional constipation.

## Formula

```
rome_iv_diarrhea iff criteria_last_3_months_onset_6_months and loose_or_watery_stools_gt_25_percent_without_predominant_pain_or_bloating and insufficient_criteria_for_ibs_d (Mearin 2016 Rome IV C3 functional diarrhea)
```

## Citation

[Bowel Disorders](https://doi.org/10.1053/j.gastro.2016.02.031)
Mearin F, Lacy BE, Chang L, Chey WD, Lembo AJ, Simren M, Spiller RC
Gastroenterology. 2016;150(6):1393-1407
DOI: [10.1053/j.gastro.2016.02.031](https://doi.org/10.1053/j.gastro.2016.02.031)

## Worked example

### Timing, loose or watery stools without pain or bloating, and not IBS-D

Given: `criteria_last_3_months_onset_6_months=true, insufficient_criteria_for_ibs_d=true, loose_or_watery_stools_gt_25_percent_without_predominant_pain_or_bloating=true`

1. Criteria fulfilled for the last 3 months with onset at least 6 months prior is true
2. Loose or watery stools without predominant abdominal pain or bothersome bloating in more than 25% of stools is true
3. Insufficient criteria for diarrhea-predominant IBS is true
4. rome_iv_diarrhea is true


### Timing and loose stools with IBS-D criteria met

Given: `criteria_last_3_months_onset_6_months=true, insufficient_criteria_for_ibs_d=false, loose_or_watery_stools_gt_25_percent_without_predominant_pain_or_bloating=true`

1. Timing and loose or watery stools without predominant pain or bloating hold
2. Insufficient criteria for diarrhea-predominant IBS is false
3. rome_iv_diarrhea is false


## Also searched as

- Rome IV functional diarrhea
- Rome IV C3
- Mearin 2016 diarrhea
- functional diarrhea criteria
- Rome IV diarrhea
- adult functional diarrhea
- diarrhea Rome IV
- Mearin C3 functional diarrhea

## Parameters

- `criteria_last_3_months_onset_6_months` (boolean, required): Criteria fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis, as assigned (Mearin 2016 C3). true or false as assigned by the caller. magent does not take a history.
- `loose_or_watery_stools_gt_25_percent_without_predominant_pain_or_bloating` (boolean, required): Loose or watery stools, without predominant abdominal pain or bothersome bloating, occurring in more than 25% of stools (Mearin 2016 C3). true or false as assigned by the caller. magent does not inspect stool.
- `insufficient_criteria_for_ibs_d` (boolean, required): Insufficient criteria for diarrhea-predominant IBS, as assigned by the caller (Mearin 2016 C3 excludes patients who meet IBS-D). true or false. magent does not apply the IBS box.

## 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_diarrhea`
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": [
    {
      "criteria_last_3_months_onset_6_months": "true",
      "insufficient_criteria_for_ibs_d": "true",
      "loose_or_watery_stools_gt_25_percent_without_predominant_pain_or_bloating": "true"
    },
    {
      "criteria_last_3_months_onset_6_months": "true",
      "insufficient_criteria_for_ibs_d": "true",
      "loose_or_watery_stools_gt_25_percent_without_predominant_pain_or_bloating": "true"
    }
  ]
}
```

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

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/rome_iv_diarrhea",
  "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": "Mearin F, Lacy BE, Chang L, Chey WD, Lembo AJ, Simren M, Spiller RC",
        "doi": "10.1053/j.gastro.2016.02.031",
        "id": "mearin-2016",
        "pmid": "27144627",
        "source": "Gastroenterology. 2016;150(6):1393-1407",
        "title": "Bowel Disorders"
      },
      "formula": "rome_iv_diarrhea",
      "formula_expression": "rome_iv_diarrhea iff criteria_last_3_months_onset_6_months and loose_or_watery_stools_gt_25_percent_without_predominant_pain_or_bloating and insufficient_criteria_for_ibs_d (Mearin 2016 Rome IV C3 functional diarrhea)",
      "criteria": [
        {
          "factor": "criteria_last_3_months_onset_6_months",
          "met": true
        },
        {
          "factor": "loose_or_watery_stools_gt_25_percent_without_predominant_pain_or_bloating",
          "met": true
        },
        {
          "factor": "insufficient_criteria_for_ibs_d",
          "met": true
        }
      ],
      "rome_iv_diarrhea": 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": "Mearin F, Lacy BE, Chang L, Chey WD, Lembo AJ, Simren M, Spiller RC",
        "doi": "10.1053/j.gastro.2016.02.031",
        "id": "mearin-2016",
        "pmid": "27144627",
        "source": "Gastroenterology. 2016;150(6):1393-1407",
        "title": "Bowel Disorders"
      },
      "formula": "rome_iv_diarrhea",
      "formula_expression": "rome_iv_diarrhea iff criteria_last_3_months_onset_6_months and loose_or_watery_stools_gt_25_percent_without_predominant_pain_or_bloating and insufficient_criteria_for_ibs_d (Mearin 2016 Rome IV C3 functional diarrhea)",
      "criteria": [
        {
          "factor": "criteria_last_3_months_onset_6_months",
          "met": true
        },
        {
          "factor": "loose_or_watery_stools_gt_25_percent_without_predominant_pain_or_bloating",
          "met": true
        },
        {
          "factor": "insufficient_criteria_for_ibs_d",
          "met": true
        }
      ],
      "rome_iv_diarrhea": true
    }
  ]
}
```

## Response fields

- `formula` (string): rome_iv_diarrhea
- `formula_expression` (string): Mearin 2016 Rome IV C3: last 3 months with 6-month onset, loose or watery stools >25% without predominant pain or bloating, and insufficient IBS-D criteria
- `rome_iv_diarrhea` (boolean): true only when timing, loose or watery stools without predominant pain or bloating in >25% of stools, and insufficient IBS-D criteria all hold. Not a diagnosis.
- `criteria` (array): Per-factor rows with factor and met for the three C3 flags
- `citation` (object): Mearin 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": "Mearin F, Lacy BE, Chang L, Chey WD, Lembo AJ, Simren M, Spiller RC",
    "doi": "10.1053/j.gastro.2016.02.031",
    "id": "mearin-2016",
    "pmid": "27144627",
    "source": "Gastroenterology. 2016;150(6):1393-1407",
    "title": "Bowel Disorders"
  },
  "formula": "rome_iv_diarrhea",
  "formula_expression": "rome_iv_diarrhea iff criteria_last_3_months_onset_6_months and loose_or_watery_stools_gt_25_percent_without_predominant_pain_or_bloating and insufficient_criteria_for_ibs_d (Mearin 2016 Rome IV C3 functional diarrhea)",
  "criteria": [
    {
      "factor": "criteria_last_3_months_onset_6_months",
      "met": true
    },
    {
      "factor": "loose_or_watery_stools_gt_25_percent_without_predominant_pain_or_bloating",
      "met": true
    },
    {
      "factor": "insufficient_criteria_for_ibs_d",
      "met": true
    }
  ],
  "rome_iv_diarrhea": true
}
```

## Errors

- 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 IBS](https://magentlab.com/docs/rome-iv-ibs) — Apply the Mearin 2016 Rome IV IBS diagnostic criteria and return supporting_features_met (0-3) and whether the published IBS box holds (rome_iv_ibs).
- [Rome IV FC](https://magentlab.com/docs/rome-iv-fc) — Apply the Mearin 2016 Rome IV C2 functional constipation criteria and return symptom_count (0-6) and whether the published C2 box holds (rome_iv_fc).
- [Bristol stool](https://magentlab.com/docs/bristol-stool) — Return the Lewis 1997 Bristol stool form scale type 1-7 from a caller-assigned integer, with the published form wording.

## 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.