Infection / VTE · LIVE

RIPASA score

Sum the Chong 2010 RIPASA points from 15 caller-assigned findings and return below_cutoff (<7.5) or at_or_above_cutoff (≥7.5) from the derivation ROC only.

LIVE $0.005 USDC GET /api/calc/ripasa

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

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

What it computes

Sum the Chong 2010 RIPASA points from 15 caller-assigned findings and return below_cutoff (<7.5) or at_or_above_cutoff (≥7.5) from the derivation ROC only.

When to use

When an agent needs the published Chong 2010 RIPASA total and must not invent abdominal findings, laboratory cutoffs, identity-card status, an appendicitis diagnosis, or an operating-room protocol.

When not to use

Not a medical device. Not an appendicitis diagnosis or operating-room protocol.
Fever, raised WCC, and foreign NRIC are caller-assigned flags. magent does not apply a temperature or WBC cutoff and does not read identity documents.
Findings are caller-assigned. magent does not examine the abdomen.
Bands are the Chong 2010 derivation ROC cutoff only (<7.5 below_cutoff; ≥7.5 at_or_above_cutoff). magent does not add probable or possible labels from later papers.

Formula

RIPASA = (age<40 → 1.0; age≥40 → 0.5) + (male 1.0; female 0.5) + 0.5*rif_pain + 0.5*migration_to_rif + nausea_vomiting + anorexia + (symptoms_lt_48h 1.0; else 0.5) + rif_tenderness + 2*guarding + rebound_tenderness + 2*rovsing_sign + fever + raised_wcc + negative_urinalysis + foreign_nric; Chong 2010; max 16; <7.5 below_cutoff, ≥7.5 at_or_above_cutoff

Citation

Title: Development of the RIPASA score: a new appendicitis scoring system for the diagnosis of acute appendicitis
Authors: Chong CF, Adi MIW, Thien A, Suyoi A, Mackie AJ, Tin AS, Tripathi S, Jaman NH, Tan KK, Kok KY, Mathew VV, Paw O, Chua HB, Yapp SK
Source: Singapore Med J. 2010;51(3):220-225
DOI: none

Worked example

Age 50, female, all flags false, symptoms 48h or longer

Given: age=50anorexia=falsefever=falseforeign_nric=falseguarding=falsemigration_to_rif=falsenausea_vomiting=falsenegative_urinalysis=falseraised_wcc=falserebound_tenderness=falserif_pain=falserif_tenderness=falserovsing_sign=falsesex=femalesymptoms_lt_48h=false

Age 50 ≥40 → 0.5; female → 0.5; symptoms_lt_48h false → 0.5; remaining flags false → 0
Score = 1.5 (max 16); ripasa_band = below_cutoff (<7.5)

Derivation ROC cutoff 7.5

Given: age=50anorexia=truefever=falseforeign_nric=falseguarding=truemigration_to_rif=falsenausea_vomiting=truenegative_urinalysis=falseraised_wcc=falserebound_tenderness=falserif_pain=falserif_tenderness=falserovsing_sign=truesex=femalesymptoms_lt_48h=false

Baseline 1.5 + nausea_vomiting 1 + anorexia 1 + guarding 2 + rovsing_sign 2
Score = 7.5 (max 16); ripasa_band = at_or_above_cutoff (≥7.5)

Also searched as

RIPASA score
RIPASA appendicitis
Chong 2010
Raja Isteri Pengiran Anak Saleha
appendicitis scoring system
RIPASA
RIF appendicitis score
foreign NRIC appendicitis

Try

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

/api/calc/ripasa?age=50&sex=female&rif_pain=false&migration_to_rif=false&nausea_vomiting=false&anorexia=false&symptoms_lt_48h=false&rif_tenderness=false&guarding=false&rebound_tenderness=false&rovsing_sign=false&fever=false&raised_wcc=false&negative_urinalysis=false&foreign_nric=false

Full URL: https://api.magentlab.com/api/calc/ripasa?age=50&sex=female&rif_pain=false&migration_to_rif=false&nausea_vomiting=false&anorexia=false&symptoms_lt_48h=false&rif_tenderness=false&guarding=false&rebound_tenderness=false&rovsing_sign=false&fever=false&raised_wcc=false&negative_urinalysis=false&foreign_nric=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/ripasa?age=50&sex=female&rif_pain=false&migration_to_rif=false&nausea_vomiting=false&anorexia=false&symptoms_lt_48h=false&rif_tenderness=false&guarding=false&rebound_tenderness=false&rovsing_sign=false&fever=false&raised_wcc=false&negative_urinalysis=false&foreign_nric=false"

Parameters

Name	Type	Required	Description
`age`	integer	required	Age in years as an integer from 1 to 120 (Chong 2010). <40 scores 1.0; ≥40 scores 0.5 (age 40 is the ≥40 arm). magent does not assign age.
`sex`	string	required · female, male	Caller-assigned sex (Chong 2010). male scores 1.0; female scores 0.5. magent does not assign sex.
`rif_pain`	boolean	required	Pain in the right iliac fossa (Chong 2010). true scores 0.5. magent does not take a history.
`migration_to_rif`	boolean	required	Migration of pain to the right iliac fossa (Chong 2010). true scores 0.5. magent does not take a history.
`nausea_vomiting`	boolean	required	Nausea or vomiting (Chong 2010). true scores 1.0. magent does not take a history.
`anorexia`	boolean	required	Anorexia (Chong 2010). true scores 1.0. magent does not take a history.
`symptoms_lt_48h`	boolean	required	true when symptom duration is under 48 hours (Chong 2010 <48h arm, 1.0). false scores 0.5 (the >48h arm; 48 hours is locked to this arm). magent does not timestamp onset.
`rif_tenderness`	boolean	required	Right-iliac-fossa tenderness (Chong 2010). true scores 1.0. magent does not examine the abdomen.
`guarding`	boolean	required	Guarding (Chong 2010). true scores 2.0. magent does not examine the abdomen.
`rebound_tenderness`	boolean	required	Rebound tenderness (Chong 2010). true scores 1.0. magent does not examine the abdomen.
`rovsing_sign`	boolean	required	Rovsing sign (Chong 2010). true scores 2.0. magent does not examine the abdomen.
`fever`	boolean	required	Caller-assigned fever flag (Chong 2010). true scores 1.0. magent does not apply a °C cutoff.
`raised_wcc`	boolean	required	Caller-assigned raised white-cell-count flag (Chong 2010). true scores 1.0. magent does not apply a WBC cutoff.
`negative_urinalysis`	boolean	required	Negative urinalysis (Chong 2010). true scores 1.0. magent does not assay urine.
`foreign_nric`	boolean	required	Caller-assigned foreign national registration identity card item (Chong 2010). true scores 1.0. magent does not read identity documents.

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/ripasa 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": [
    {
      "age": "50",
      "anorexia": "false",
      "fever": "false",
      "foreign_nric": "false",
      "guarding": "false",
      "migration_to_rif": "false",
      "nausea_vomiting": "false",
      "negative_urinalysis": "false",
      "raised_wcc": "false",
      "rebound_tenderness": "false",
      "rif_pain": "false",
      "rif_tenderness": "false",
      "rovsing_sign": "false",
      "sex": "female",
      "symptoms_lt_48h": "false"
    },
    {
      "age": "50",
      "anorexia": "false",
      "fever": "false",
      "foreign_nric": "false",
      "guarding": "false",
      "migration_to_rif": "false",
      "nausea_vomiting": "false",
      "negative_urinalysis": "false",
      "raised_wcc": "false",
      "rebound_tenderness": "false",
      "rif_pain": "false",
      "rif_tenderness": "false",
      "rovsing_sign": "false",
      "sex": "female",
      "symptoms_lt_48h": "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/ripasa",
  "items": [
    {
      "components": [
        {
          "value": 50,
          "factor": "age",
          "points": 0.5,
          "present": true
        },
        {
          "value": "female",
          "factor": "sex",
          "points": 0.5,
          "present": true
        },
        {
          "factor": "rif_pain",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "migration_to_rif",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "nausea_vomiting",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "anorexia",
          "points": 0.0,
          "present": false
        },
        {
          "value": false,
          "factor": "symptoms_lt_48h",
          "points": 0.5,
          "present": true
        },
        {
          "factor": "rif_tenderness",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "guarding",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "rebound_tenderness",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "rovsing_sign",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "fever",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "raised_wcc",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "negative_urinalysis",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "foreign_nric",
          "points": 0.0,
          "present": false
        }
      ],
      "age": 50,
      "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": "Chong CF, Adi MIW, Thien A, Suyoi A, Mackie AJ, Tin AS, Tripathi S, Jaman NH, Tan KK, Kok KY, Mathew VV, Paw O, Chua HB, Yapp SK",
        "id": "chong-2010",
        "pmid": "20428744",
        "source": "Singapore Med J. 2010;51(3):220-225",
        "title": "Development of the RIPASA score: a new appendicitis scoring system for the diagnosis of acute appendicitis"
      },
      "formula": "ripasa",
      "formula_expression": "RIPASA = (age<40 → 1.0; age≥40 → 0.5) + (male 1.0; female 0.5) + 0.5*rif_pain + 0.5*migration_to_rif + nausea_vomiting + anorexia + (symptoms_lt_48h 1.0; else 0.5) + rif_tenderness + 2*guarding + rebound_tenderness + 2*rovsing_sign + fever + raised_wcc + negative_urinalysis + foreign_nric; Chong 2010; max 16; <7.5 below_cutoff, ≥7.5 at_or_above_cutoff",
      "max_score": 16,
      "score": 1.5,
      "sex": "female",
      "ripasa_band": "below_cutoff"
    },
    {
      "components": [
        {
          "value": 50,
          "factor": "age",
          "points": 0.5,
          "present": true
        },
        {
          "value": "female",
          "factor": "sex",
          "points": 0.5,
          "present": true
        },
        {
          "factor": "rif_pain",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "migration_to_rif",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "nausea_vomiting",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "anorexia",
          "points": 0.0,
          "present": false
        },
        {
          "value": false,
          "factor": "symptoms_lt_48h",
          "points": 0.5,
          "present": true
        },
        {
          "factor": "rif_tenderness",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "guarding",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "rebound_tenderness",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "rovsing_sign",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "fever",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "raised_wcc",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "negative_urinalysis",
          "points": 0.0,
          "present": false
        },
        {
          "factor": "foreign_nric",
          "points": 0.0,
          "present": false
        }
      ],
      "age": 50,
      "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": "Chong CF, Adi MIW, Thien A, Suyoi A, Mackie AJ, Tin AS, Tripathi S, Jaman NH, Tan KK, Kok KY, Mathew VV, Paw O, Chua HB, Yapp SK",
        "id": "chong-2010",
        "pmid": "20428744",
        "source": "Singapore Med J. 2010;51(3):220-225",
        "title": "Development of the RIPASA score: a new appendicitis scoring system for the diagnosis of acute appendicitis"
      },
      "formula": "ripasa",
      "formula_expression": "RIPASA = (age<40 → 1.0; age≥40 → 0.5) + (male 1.0; female 0.5) + 0.5*rif_pain + 0.5*migration_to_rif + nausea_vomiting + anorexia + (symptoms_lt_48h 1.0; else 0.5) + rif_tenderness + 2*guarding + rebound_tenderness + 2*rovsing_sign + fever + raised_wcc + negative_urinalysis + foreign_nric; Chong 2010; max 16; <7.5 below_cutoff, ≥7.5 at_or_above_cutoff",
      "max_score": 16,
      "score": 1.5,
      "sex": "female",
      "ripasa_band": "below_cutoff"
    }
  ]
}

Response

Field	Type	Description
`formula`	string	ripasa
`formula_expression`	string	Exact expression used
`score`	number	Chong 2010 RIPASA points 0.5-16, 0.5 steps
`max_score`	integer	Always 16
`ripasa_band`	string	below_cutoff when score is <7.5, at_or_above_cutoff when score is ≥7.5 (Chong 2010 derivation ROC). Not an appendicitis diagnosis.
`age`	integer	Age in years used for the <40 / ≥40 split
`sex`	string	female or male
`components`	array	Per-factor points
`citation`	object	Chong 2010 Singapore Med J citation
`disclaimer`	string	Not-a-device notice

Example JSON

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

{
  "components": [
    {
      "value": 50,
      "factor": "age",
      "points": 0.5,
      "present": true
    },
    {
      "value": "female",
      "factor": "sex",
      "points": 0.5,
      "present": true
    },
    {
      "factor": "rif_pain",
      "points": 0.0,
      "present": false
    },
    {
      "factor": "migration_to_rif",
      "points": 0.0,
      "present": false
    },
    {
      "factor": "nausea_vomiting",
      "points": 0.0,
      "present": false
    },
    {
      "factor": "anorexia",
      "points": 0.0,
      "present": false
    },
    {
      "value": false,
      "factor": "symptoms_lt_48h",
      "points": 0.5,
      "present": true
    },
    {
      "factor": "rif_tenderness",
      "points": 0.0,
      "present": false
    },
    {
      "factor": "guarding",
      "points": 0.0,
      "present": false
    },
    {
      "factor": "rebound_tenderness",
      "points": 0.0,
      "present": false
    },
    {
      "factor": "rovsing_sign",
      "points": 0.0,
      "present": false
    },
    {
      "factor": "fever",
      "points": 0.0,
      "present": false
    },
    {
      "factor": "raised_wcc",
      "points": 0.0,
      "present": false
    },
    {
      "factor": "negative_urinalysis",
      "points": 0.0,
      "present": false
    },
    {
      "factor": "foreign_nric",
      "points": 0.0,
      "present": false
    }
  ],
  "age": 50,
  "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": "Chong CF, Adi MIW, Thien A, Suyoi A, Mackie AJ, Tin AS, Tripathi S, Jaman NH, Tan KK, Kok KY, Mathew VV, Paw O, Chua HB, Yapp SK",
    "id": "chong-2010",
    "pmid": "20428744",
    "source": "Singapore Med J. 2010;51(3):220-225",
    "title": "Development of the RIPASA score: a new appendicitis scoring system for the diagnosis of acute appendicitis"
  },
  "formula": "ripasa",
  "formula_expression": "RIPASA = (age<40 → 1.0; age≥40 → 0.5) + (male 1.0; female 0.5) + 0.5*rif_pain + 0.5*migration_to_rif + nausea_vomiting + anorexia + (symptoms_lt_48h 1.0; else 0.5) + rif_tenderness + 2*guarding + rebound_tenderness + 2*rovsing_sign + fever + raised_wcc + negative_urinalysis + foreign_nric; Chong 2010; max 16; <7.5 below_cutoff, ≥7.5 at_or_above_cutoff",
  "max_score": 16,
  "score": 1.5,
  "sex": "female",
  "ripasa_band": "below_cutoff"
}

Client errors (HTTP 400)

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

HTTP	Code	When
400	`invalid_ripasa_age`	age must be an integer from 1 to 120 (Chong 2010 RIPASA). Returned before settlement; you are not charged.
400	`invalid_sex`	sex must be female or male Returned before settlement; you are not charged.
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

Alvarado score — Compute the Alvarado 1986 MANTRELS score from caller-assigned findings, temperature, WBC, and neutrophil percent.
AIR score — Compute the Andersson 2008 appendicitis inflammatory response (AIR) score from caller-assigned findings, temperature, WBC, neutrophil percent, and CRP in mg/L.

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.