Recommendations for Diagnostic Evaluation of Suspected Pulmonary Embolism


These decision rules are based on the Wells score for assessing pulmonary embolism risk. 

Artifact Type
Creation Date

Artifact Creation and Usage


Ronilda Lacson
Ramin Khorasani
Ali S. Raja
Louise Schneider
Michael Bakhtin
Mark Isabelle
Ivan Ip

IP Attestation The author asserts that this artifact has been developed in compliance with the intellectual property rights attributed to the source material.

This CDS artifact and related data specifications are owned and stewarded by the Brigham and Women's Hospital (BWH). BWH is not responsible for any use of the CDS artifact. BWH makes no representations, warranties, or endorsement about the quality of any organization or physician that uses this CDS artifact.

MeSH Topics
Implementation Details
Miscellaneous Files
Repository Information
Knowledge Level

Structured code that is interpretable by a computer (includes data elements, value sets, logic)

Purpose and Usage

The purpose of this CDS is to optimize the appropriate use of CT pulmonary angiogram for evaluating suspected acute pulmonary embolism.

Intended Population

All adult patients (>=18 years of age) with suspected pulmonary embolism for whom CT pulmonary embolism is ordered.


The tool is embedded into the Electronic Health Record, triggered by an order for CT pulmonary angiogram. 


This CDS should only be used in adult patients (18 years of age or over) who have suspected pulmonary embolism (PE). Specifically, it is triggered by an order for CT pulmonary angiogram (CTPA) for evaluating patients who have suspected PE. In addition, this CDS has not been validated for use in pregnant patients. Caution should be applied in patients with severe allergy to iodinated contrast and patients with EGFR<30 for whom alternative imaging should be considered.

Test Patients
Supporting Evidence
Source Description

A published study demonstrated that a clinical model can be safely used in a management strategy for patients with suspected pulmonary embolism. This, combined with D-dimer results, would optimize the appropriate use of CT pulmonary angiogram in a large proportion of patients with suspected pulmonary embolism.


Wells PS, Anderson DR, Rodger M, et al. Derivation of a simple clinical model to categorize patients probability of pulmonary embolism: increasing the models utility with the SimpliRED D-dimer. Thromb Haemost. 2000;83(3):416-420.

Wells PS, Ginsberg JS, Anderson DR, Kearon C, Gent M, Turpie AG, Bormanis J, Weitz J, Chamberlain M, Bowie D, Barnes D, Hirsh J. Use of a clinical model for safe management of patients with suspected pulmonary embolism. Ann Intern Med. 1998 Dec 15;129(12):997-1005. doi: 10.7326/0003-4819-129-12-199812150-00002. PMID: 9867786.


(1) For patients with suspected pulmonary embolism, the combination of a Wells score < or =4.0 by the clinical prediction rule (below) and a negative D-Dimer result may safely exclude PE in a large proportion of patients with suspected PE, and therefore CT pulmonary angiogram is not routinely recommended for testing.

(2) Otherwise, if (a) the Wells score is > 4.0 or (b) the patient has an elevated D-dimer result, CT pulmonary angiogram may be recommended.

Criteria used to calculate Wells scoreValue
Clinical signs and symptoms of DVT (minimum leg swelling and pain with palpation of the deep veins)3.0
An alternative diagnosis is less likely than PE3.0
Heart rate >100 1.5
Immobilization or surgery in the previous 4 weeks1.5
Previous DVT/PE1.5
Malignancy (on treatment, treated in the last 6 months or palliative)1.0
Strength of Recommendation

Recommendation (1): Class of evidence IIa. Weight of evidence/opinion is in favor of usefulness or efficacy; guideline should be considered.

Recommendation (2): Class of evidence I. Evidence or general agreement that a procedure is beneficial, useful or effective; guideline is recommended.

Source: Torbicki A, Perrier A, Konstantinides S, Agnelli G, Galiè N, Pruszczyk P, Bengel F, Brady AJ, Ferreira D, Janssens U, Klepetko W, Mayer E, Remy-Jardin M, Bassand JP; ESC Committee for Practice Guidelines (CPG). Guidelines on the diagnosis and management of acute pulmonary embolism: the Task Force for the Diagnosis and Management of Acute Pulmonary Embolism of the European Society of Cardiology (ESC). Eur Heart J. 2008 Sep;29(18):2276-315. doi: 10.1093/eurheartj/ehn310. Epub 2008 Aug 30. PMID: 18757870

Quality of Evidence

Strength of Evidence**

Based on Oxford Grade (2011): Level 5 (Mechanism -based reasoning)

Based on Oxford Grade (2009): Level 5 (Expert opinion without explicit critical appraisal or based on physiology, bench research, or "first principles"

**The clinical prediction  rule is actually based on V/Q scan, LE ultrasound, and angiography, which were standards at the time. While the study design would make it 1b, there is a translation of imaging modality (to CT pulmonary angiogram) that is not direct. By definition, it must be graded as expert opinion (5-I).

Source: Harvard Medical School Library of Evidence. https://libraryofevidence.med.harvard.edu/app/library.

Artifact Representation

Provider orders CT Pulmonary Angiogram (CTPA)


Adult Patients (age 18 years or older)



Severe allergy to iodinated contrast

Estimated glomerular filtration rate (EGFR) <30

Interventions and Actions

1) If Patient does not meet the Inclusion criteria or meets the Exclusion criteria, the CDS will not proceed any further.

2) Otherwise, if D-dimer is elevated or Wells score > 4, continue with CTPA order.

3) Otherwise, if D-dimer is not available, DISPLAY that D-dimer should be ordered and evaluated prior to ordering CTPA.

4) Otherwise, if D-dimer is normal and Wells score <= 4, DISPLAY that CTPA is not recommended.

5) If Wells score is not available, DISPLAY questionnaire with elements that are needed to perform the calculation. 

**There is no need to document reasons when CTPA is not ordered when criteria are met. The trigger is an order for CTPA and the CDS will not proceed further if the criteria for getting CTPA is met.

Logic Files
Testing Experience