# Wells Score for DVT Calculator

> Sums the Wells clinical criteria for suspected deep vein thrombosis and reports the three-tier (low/moderate/high) and two-tier (unlikely/likely) pretest probability categories.

- Calculator id: `wells-score-dvt` · Category: Medical & Clinical (`medical`) · Tool name: `calculate_wells_dvt_score`
- Canonical page: https://tttkmbb.com/medical/wells-score-dvt · This document: https://tttkmbb.com/medical/wells-score-dvt.md · JSON definition: https://tttkmbb.com/medical/wells-score-dvt.json

## Purpose

Sums the Wells clinical criteria for suspected deep vein thrombosis and reports the three-tier (low/moderate/high) and two-tier (unlikely/likely) pretest probability categories.

**Use when:** You are structuring the pretest probability of a first lower-limb DVT before D-dimer testing or ultrasound.

**Do not use when:** Suspected pulmonary embolism (the Wells PE score differs), pregnancy, or upper-limb DVT, where the score was not validated.

## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `active_cancer` | boolean |  | optional, default false | +1 point. |
| `paralysis_or_immobilisation` | boolean |  | optional, default false | +1 point. |
| `bedridden_or_major_surgery` | boolean |  | optional, default false | +1 point. |
| `localised_tenderness` | boolean |  | optional, default false | +1 point. |
| `entire_leg_swollen` | boolean |  | optional, default false | +1 point. |
| `calf_swelling_over_3cm` | boolean |  | optional, default false | +1 point. |
| `pitting_oedema` | boolean |  | optional, default false | +1 point. |
| `collateral_superficial_veins` | boolean |  | optional, default false | +1 point. |
| `previous_dvt` | boolean |  | optional, default false | +1 point (added in the 2003 modification). |
| `alternative_diagnosis_likely` | boolean |  | optional, default false | −2 points. |

## Output

| Field | Type | Unit | Description |
| --- | --- | --- | --- |
| `score` | integer |  | Sum of the criteria (−2 to 9). |
| `three_tier_probability` | string |  | Low (≤0, about 3% DVT prevalence), moderate (1–2, about 17%) or high (≥3, about 75%). |
| `two_tier_category` | string |  | DVT unlikely (≤1) or DVT likely (≥2). |
| `criteria_met` | string_list |  | Criteria that contributed to the score. |

## Formula

`score = Σ positive criteria (1 point each) − 2 if an alternative diagnosis is at least as likely; low ≤ 0, moderate 1–2, high ≥ 3; unlikely ≤ 1, likely ≥ 2`

Prevalence figures come from the 1997 derivation cohort; in the 2003 two-tier study a low score with a negative D-dimer safely excluded DVT without ultrasound. Results are informational only and not a substitute for clinical judgement or medical advice.

## Data Sources

- Wells PS et al. (1997) Value of assessment of pretest probability of deep-vein thrombosis in clinical management, Lancet 350:1795-1798 — https://pubmed.ncbi.nlm.nih.gov/9428249/ (peer_reviewed, retrieved 2026-09-24)
- Wells PS et al. (2003) Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis, N Engl J Med 349:1227-1235 — https://pubmed.ncbi.nlm.nih.gov/13679527/ (peer_reviewed, retrieved 2026-09-24)

Data freshness: `static`. Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output.

## API

- `GET https://tttkmbb.com/api/v1/calculate/wells-score-dvt?`
- `POST https://tttkmbb.com/api/v1/calculate/wells-score-dvt` with JSON body `{"inputs": {…}}`
- Response: unified envelope (`success`, `request`, `result.values`, `result.units`, `sources`, `freshness`, `timestamp`, `next_actions`, `links`); see https://tttkmbb.com/docs/response-format.md
- Schema: https://tttkmbb.com/api/v1/calculators/wells-score-dvt · OpenAPI operationId `calculate_wells_dvt_score` in https://tttkmbb.com/openapi.json
- Authentication: none. Rate limit: fair use, see https://tttkmbb.com/docs/rate-limits.md.

## MCP

- Server: `https://tttkmbb.com/mcp` (Streamable HTTP, JSON-RPC 2.0, no auth)
- Tool:  `run_calculator` with `{"calculator_id": "wells-score-dvt", "inputs": {…}}`

## Example

- Active cancer, calf swelling, localised tenderness: inputs `{"active_cancer":true,"calf_swelling_over_3cm":true,"localised_tenderness":true}` → `{"score":3,"three_tier_probability":"High (score ≥3; about 75% DVT prevalence)","two_tier_category":"DVT likely (score ≥2)"}`
- Entire leg swollen, alternative diagnosis likely: inputs `{"entire_leg_swollen":true,"alternative_diagnosis_likely":true}` → `{"score":-1,"three_tier_probability":"Low (score ≤0; about 3% DVT prevalence)","two_tier_category":"DVT unlikely (score ≤1)"}`

```
GET https://tttkmbb.com/api/v1/calculate/wells-score-dvt?active_cancer=true&calf_swelling_over_3cm=true&localised_tenderness=true
```

## Limitations

Suspected pulmonary embolism (the Wells PE score differs), pregnancy, or upper-limb DVT, where the score was not validated. Prevalence figures come from the 1997 derivation cohort; in the 2003 two-tier study a low score with a negative D-dimer safely excluded DVT without ultrasound. Results are informational only and not a substitute for clinical judgement or medical advice. All values are computed from the formula above; no measurement or live data is involved.

## FAQ

**What do I do with the category?**

In the validated pathway, 'unlikely' plus a negative D-dimer excludes DVT; 'likely' or a positive D-dimer proceeds to compression ultrasound.

**Which version is this?**

The 2003 modified criteria (including previously documented DVT); the three-tier output uses the 1997 cut-offs, so both categorisations are shown.

## Related

- [CHA₂DS₂-VASc Score Calculator](https://tttkmbb.com/medical/cha2ds2-vasc-score.md) — Another clinical risk score with anticoagulation implications.
- [BMI Calculator](https://tttkmbb.com/health/bmi.md) — Obesity is a background risk factor for venous thrombosis.