For healthcare professionals
Wells score for DVT calculator
The Wells model for deep-vein thrombosis (DVT) is a clinical score clinicians use for outpatients with a swollen or painful leg, to sort the pretest probability of DVT into likely or unlikely before D-dimer testing and ultrasound. Nine findings score 1 point each and an alternative diagnosis at least as likely as DVT scores minus 2. This calculator is written for clinicians and is not a diagnosis.
Clinical findings
Tick each finding that is present after history and examination. If both legs have symptoms, score the more symptomatic leg. Nothing you enter leaves this page.
What you will see
The Wells DVT score from minus 2 to 9, the points for each finding, whether the pretest probability falls in the DVT likely or unlikely group, and the next tests in the authors' algorithm.
Educational only, not medical advice. Not a diagnosis. DVT is confirmed or excluded by testing, not by this score.
Source
Scarvelis D and Wells PS, CMAJ 2006: Table 1 (the clinical model with previously documented DVT, its points and the likely or unlikely cut point) and Figure 2 (the testing algorithm). The tests check every item's points and the cut point.
Validated in
The authors write that the rule was developed and validated mainly in outpatients with suspected DVT, that pregnant women were not included, and that more than 14 studies have shown it can be reproduced (Scarvelis 2006).
Limits
The score gives a pretest probability, not a diagnosis. The authors say it should be used only after a history and examination and only when DVT is still a real possibility. It was not studied in pregnancy, and in hospital inpatients D-dimer testing is less useful because results are rarely negative. Item 'alternative diagnosis at least as likely' depends on clinical judgement.
Wells DVT scoring
Each finding adds 1 point; an alternative diagnosis at least as likely as DVT subtracts 2. A total of 2 or more means DVT is likely, and under 2 means DVT is unlikely. When both legs have symptoms, the more symptomatic leg is scored (Scarvelis 2006).
| Clinical finding | Points |
|---|---|
| Active cancer (treatment ongoing, within the last 6 months, or palliative) | 1 |
| Paralysis, paresis or recent plaster immobilization of the legs | 1 |
| Bedridden more than 3 days, or major surgery with general or regional anesthesia in the last 12 weeks | 1 |
| Localized tenderness along the deep venous system | 1 |
| Swelling of the entire leg | 1 |
| Calf swelling more than 3 cm compared with the other side, measured 10 cm below the tibial tuberosity | 1 |
| Pitting edema only in the symptomatic leg | 1 |
| Collateral superficial veins (nonvaricose) | 1 |
| Previously documented DVT | 1 |
| Alternative diagnosis at least as likely as DVT | -2 |
Source: Table 1 of Scarvelis and Wells, 2006, which presents the version of the model that adds previously documented DVT (Scarvelis 2006). The same paper notes that the rule can also sort patients into low, moderate or high probability groups; this calculator shows only the likely or unlikely grouping, because that is the cut point the paper prints.
A note on the cut point: Table 1 and the algorithm in Figure 2 both put DVT unlikely at 1 or less and likely at 2 or more, while one sentence in the paper's text reads "less than 1". This calculator follows the table and the figure.
Testing after the score
In the authors' algorithm, every patient has a D-dimer test after the pretest probability is set (Scarvelis 2006).
- DVT unlikely: a negative D-dimer means no DVT without ultrasound; a positive D-dimer leads to ultrasound.
- DVT likely: ultrasound follows whatever the D-dimer result. If the D-dimer is positive and the first scan is negative, the scan is repeated in a week.
The authors add that no D-dimer test should be used to exclude DVT when pretest probability is high, and that ultrasound in the algorithm covers the proximal veins down to the calf trifurcation (Scarvelis 2006). Local pathways and the D-dimer assay in use may differ.
Related tools
For suspected pulmonary embolism, see the Wells score for PE and the PERC rule calculator, and once it is confirmed, the PESI score calculator. To estimate the risk of a future clot in a patient admitted to a medical ward, see the Padua prediction score, and around surgery, the Caprini score. For other clinician scores on this site, see the HEART score calculator for chest pain, the CURB-65 calculator for pneumonia and the Revised Cardiac Risk Index (RCRI) before surgery. For bleeding risk in people with atrial fibrillation who take a blood thinner, see the HAS-BLED score.
Sources
- Scarvelis D, Wells PS. Diagnosis and treatment of deep-vein thrombosis. CMAJ. 2006;175(9):1087-1092. doi:10.1503/cmaj.060366. PMID 17060659. Table 1 (clinical model for predicting pretest probability of DVT), Figure 2 (diagnostic algorithm) and section on clinical prediction rules. pmc.ncbi.nlm.nih.gov/articles/PMC1609160/
Written and maintained by the uncovermyrisk.com editorial team. We do not have a medical reviewer; every claim links to its primary source above. Last reviewed: 2026-11-01. Spotted an error? See About.