# Allowable blood loss

Allowable blood loss

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/allowable_blood_loss`
HTML: https://magentlab.com/docs/allowable-blood-loss
Markdown: https://magentlab.com/docs/allowable-blood-loss.md

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

## What it computes

Compute Gross 1983 dilution-corrected allowable blood loss from a caller-supplied estimated blood volume and initial versus target hematocrit.

## When to use

When an agent needs published Gross ABL and must not invent milliliters, compute Nadler EBV inside this tool, or use the uncorrected EBV*(Hi-Hf)/Hi form.

## When not to use

- Not a transfusion trigger or order. magent does not choose a product, rate, or threshold.
- Estimated blood volume is caller-supplied. This tool does not compute Nadler EBV from height, weight, or sex.
- Dilution-corrected Gross 1983 only. Not the uncorrected EBV * (Hi - Hf) / Hi form.

## Formula

```
abl_ml = estimated_blood_volume_ml * (hct_initial_percent - hct_target_percent) / ((hct_initial_percent + hct_target_percent) / 2)
```

## Citation

[Estimating allowable blood loss: corrected for dilution](https://doi.org/10.1097/00000542-198303000-00016)
Gross JB
Anesthesiology. 1983;58(3):277-280
DOI: [10.1097/00000542-198303000-00016](https://doi.org/10.1097/00000542-198303000-00016)

## Worked example

### EBV 5000 mL, Hct 40 to 30

Given: `estimated_blood_volume_ml=5000, hct_initial_percent=40, hct_target_percent=30`

1. Hct_avg = (40 + 30) / 2 = 35
2. abl_ml = 5000 * (40 - 30) / 35 = 1428.6 mL


## Also searched as

- allowable blood loss
- maximum allowable blood loss
- Gross ABL
- ABL formula
- dilution-corrected ABL
- allowable blood loss hematocrit
- MABL

## Parameters

- `estimated_blood_volume_ml` (number, required): Caller-supplied estimated blood volume in mL (50-15000). Required. magent does not compute Nadler EBV.
- `hct_initial_percent` (number, required): Initial hematocrit as a percent (10-70).
- `hct_target_percent` (number, required): Target hematocrit as a percent (10-70). Must be strictly less than hct_initial_percent.

## 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/allowable_blood_loss`
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": [
    {
      "estimated_blood_volume_ml": "5000",
      "hct_initial_percent": "40",
      "hct_target_percent": "30"
    },
    {
      "estimated_blood_volume_ml": "5000",
      "hct_initial_percent": "40",
      "hct_target_percent": "30"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/allowable-blood-loss

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/allowable_blood_loss",
  "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": "Gross JB",
        "doi": "10.1097/00000542-198303000-00016",
        "id": "gross-1983",
        "source": "Anesthesiology. 1983;58(3):277-280",
        "title": "Estimating allowable blood loss: corrected for dilution"
      },
      "formula": "gross_1983",
      "formula_expression": "abl_ml = estimated_blood_volume_ml * (hct_initial_percent - hct_target_percent) / ((hct_initial_percent + hct_target_percent) / 2)",
      "abl_ml": 1428.6,
      "estimated_blood_volume_ml": 5.0e3,
      "hct_initial_percent": 40.0,
      "hct_target_percent": 30.0
    },
    {
      "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": "Gross JB",
        "doi": "10.1097/00000542-198303000-00016",
        "id": "gross-1983",
        "source": "Anesthesiology. 1983;58(3):277-280",
        "title": "Estimating allowable blood loss: corrected for dilution"
      },
      "formula": "gross_1983",
      "formula_expression": "abl_ml = estimated_blood_volume_ml * (hct_initial_percent - hct_target_percent) / ((hct_initial_percent + hct_target_percent) / 2)",
      "abl_ml": 1428.6,
      "estimated_blood_volume_ml": 5.0e3,
      "hct_initial_percent": 40.0,
      "hct_target_percent": 30.0
    }
  ]
}
```

## Response fields

- `formula` (string): gross_1983
- `formula_expression` (string): Exact Gross 1983 expression
- `estimated_blood_volume_ml` (number): Caller-supplied estimated blood volume in mL
- `hct_initial_percent` (number): Initial hematocrit percent used
- `hct_target_percent` (number): Target hematocrit percent used
- `abl_ml` (number): Dilution-corrected allowable blood loss in mL, 1 decimal
- `citation` (object): Gross Anesthesiology 1983 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": "Gross JB",
    "doi": "10.1097/00000542-198303000-00016",
    "id": "gross-1983",
    "source": "Anesthesiology. 1983;58(3):277-280",
    "title": "Estimating allowable blood loss: corrected for dilution"
  },
  "formula": "gross_1983",
  "formula_expression": "abl_ml = estimated_blood_volume_ml * (hct_initial_percent - hct_target_percent) / ((hct_initial_percent + hct_target_percent) / 2)",
  "abl_ml": 1428.6,
  "estimated_blood_volume_ml": 5.0e3,
  "hct_initial_percent": 40.0,
  "hct_target_percent": 30.0
}
```

## Errors

- HTTP 400 `invalid_estimated_blood_volume`: estimated_blood_volume_ml must be a number from 50 to 15000. Returned before settlement; you are not charged.
- HTTP 400 `invalid_hematocrit`: hematocrit_percent must be a number from 10 to 70. Returned before settlement; you are not charged.
- HTTP 400 `invalid_target_hematocrit`: hct_target_percent must be 10-70 and strictly less than hct_initial_percent. 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

- [Nadler blood volume](https://magentlab.com/docs/nadler) — Compute Nadler 1962 predicted blood volume in liters and milliliters from height, weight, and sex.
- [ANC](https://magentlab.com/docs/anc) — Compute absolute neutrophil count from WBC and neutrophil plus band percents, plus a Bodey 1966 granulocyte band.

## 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 echoing accepted, payload, and extensions when present).
- 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.
- 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.