The Wells score is a

clinical prediction rule A clinical prediction rule or clinical probability assessment specifies how to use medical signs, symptoms, and other findings to estimate the probability of a specific disease or clinical outcome. Physicians have difficulty in estimated risks of ...

used to classify patients suspected of having

pulmonary embolism Pulmonary embolism (PE) is a blockage of an pulmonary artery, artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include dyspnea, shortness of breath, chest pain p ...

(PE) into risk groups by quantifying the

pre-test probability Pre-test probability and post-test probability (alternatively spelled pretest and posttest probability) are the probabilities of the presence of a condition (such as a disease) before and after a diagnostic test, respectively. ''Post-test probabi ...

. It is different than Well's score for DVT (deep vein thrombosis). It was originally described by Well's et al. in 1998, using their experience from creating Well's score for DVT in 1995. Today, there are multiple (revised or simplified) versions of the rule, which may lead to ambiguity. The purpose of the rule is to select the best method of investigation (e.g. D-dimer testing,

CT angiography Computed tomography angiography (also called CT angiography or CTA) is a computed tomography technique used for angiography—the visualization of arteries and veins—throughout the human body. Using contrast injected into the blood vessels, i ...

) for ruling in or ruling out the diagnosis of PE, and to improve the interpretation and accuracy of subsequent testing, based on a Bayesian framework for the probability of the diagnosis. The rule is more objective than clinician gestalt, but still includes subjective opinion (unlike e.g.

Geneva score The Geneva score is a clinical prediction rule used in determining the pre-test probability of pulmonary embolism (PE) based on a patient's risk factors and clinical findings. It has been shown to be as accurate as the Wells Score, and is less rel ...

Original algorithm

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). It categorized patients into 3 categories: low / moderate / high probability. It was formulated in the form of an algorithm, not a score. Subsequent testing choices were V/Q scanning, pulmonary

angiography Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is performe ...

, and serial

compression ultrasound Medical ultrasound includes diagnostic techniques (mainly medical imaging, imaging techniques) using ultrasound, as well as therapeutic ultrasound, therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal ...

Revised score

The emergence of

D-dimer D-dimer (or D dimer) is a fibrin degradation product (or FDP), a small protein fragment present in the blood after a blood clot is degraded by fibrinolysis. It is so named because it contains two D fragments of the fibrin protein joined by a cross ...

assays prompted the revision of the rule. This version was published as a score, and according to the final score, patients could be categorized in either 3 groups (low / intermediate / high risk) or 2 groups (low / high risk) Subsequent testing choices included D-dimer testing for low risk cases, and V/Q scanning, pulmonary angiography, and compression ultrasonography for intermediate / high risk patients and low-risk patients with positive D-dimer results. Risk of PE using 3 categories (data from the derivation group) Risk of PE using 2 categories (data from the derivation group)

References

{{reflist Medical terminology Medical tests Vascular diseases