The Wells score is a validated clinical prediction tool for estimating the pre-test probability of deep vein thrombosis (DVT) or pulmonary embolism (PE). The DVT version uses the 2003 modified Wells criteria, scoring −2 to +9, with DVT unlikely below 2 points and DVT likely at 2 or above. The PE version scores 0 to 12.5, with PE unlikely at 4 or below and PE likely above 4. The tool calculates the score only — clinical interpretation and decisions about D-dimer testing or imaging remain with the treating clinician.