The Wells score is a clinical prediction rule used to classify patients suspected of having pulmonary embolism (PE) into risk groups by quantifying the pre-test probability.
[2] Today, there are multiple (revised or simplified) versions of the rule, which may lead to ambiguity.
The rule is more objective than clinician gestalt, but still includes subjective opinion (unlike e.g. Geneva score).
Originally it was developed in 1998 to improve the low specificity of V/Q scan results (which then had a more important role in the workup of PE than now).
Subsequent testing choices were V/Q scanning, pulmonary angiography, and serial compression ultrasound.