The Wells Score for Pulmonary Embolism (PE) is a validated clinical prediction rule used to estimate the probability that a patient has an acute pulmonary embolism. Developed by Dr. Philip Wells and colleagues, the score combines clinical features and recognised risk factors to support healthcare professionals when assessing patients with suspected venous thromboembolism.
Pulmonary embolism occurs when a blood clot, most commonly originating from a deep vein thrombosis (DVT) in the lower limbs, travels to the pulmonary arteries and obstructs blood flow within the lungs. PE is a potentially life-threatening medical emergency that requires prompt recognition and appropriate investigation.
The Wells Score assigns points to several clinical findings, including signs and symptoms of deep vein thrombosis, an alternative diagnosis being less likely than pulmonary embolism, tachycardia, recent surgery or immobilisation, previous DVT or PE, haemoptysis, and active malignancy. The combined score is then used to estimate the patient’s clinical probability of pulmonary embolism using either a three-tier (low, intermediate, or high probability) or simplified two-tier (“PE unlikely” or “PE likely”) classification, depending on local clinical practice and guidelines.
In routine clinical care, the Wells Score is commonly used alongside D-dimer testing and diagnostic imaging such as computed tomography pulmonary angiography (CTPA) or ventilation-perfusion (V/Q) scanning. Patients with a low clinical probability and a negative D-dimer result may not require imaging, whereas patients with a higher probability or positive D-dimer generally undergo further diagnostic investigation. This evidence-based approach helps reduce unnecessary imaging while ensuring that patients at increased risk receive timely assessment.
The Wells Score is intended to support, rather than replace, clinical judgement. Healthcare professionals should always interpret the result alongside the patient’s history, physical examination, vital signs, laboratory findings, and imaging where appropriate. Clinical suspicion should remain the primary driver of investigation, particularly in patients with atypical presentations or significant comorbidities.
The Wells Score has been incorporated into numerous national and international guidelines for the assessment of suspected pulmonary embolism and remains one of the most widely used clinical prediction tools in emergency medicine, acute medicine, respiratory medicine, and primary care.
At MediCalc, the Wells Score for Pulmonary Embolism calculator is based on the original validated scoring system and is designed to provide healthcare professionals with a rapid and reliable estimate of clinical probability. The calculator should always be used in conjunction with current clinical guidelines, appropriate diagnostic testing, and professional clinical judgement to support safe, evidence-based patient care.