Practice Guidelines

Diagnosing VTE: Guidelines from the American Society of Hematology


Am Fam Physician. 2019 Dec 1;100(11):716-717.

Author disclosure: No relevant financial affiliations.

Key Points for Practice

• Pretest probability using the Wells, Geneva, or Constans score determines the need for diagnostic testing for VTE.

• A d-dimer test alone can be used to rule out VTE for patients with a low or intermediate pretest probability of PE, low pretest probability of lower extremity DVT, or low pretest probability of upper extremity DVT.

• In patients with a low or intermediate pretest probability of PE but a positive d-dimer result, a V/Q scan is recommended over CTPA, but CTPA is recommended for patients with a high pretest probability.

• Ultrasonography is recommended as the initial test for patients with a high pretest probability of lower extremity or upper extremity DVT with confirmatory testing if negative.

From the AFP Editors

An accurate diagnosis of venous thromboembolism (VTE) is essential to avoid morbidity and mortality from both thrombosis and unnecessary treatment. Diagnostic tests for VTE are often unreliable, with accuracy that is dependent on the probability of VTE. The American Society of Hematology has published recommendations for determining the optimal diagnostic strategy based on pretest risk.

Clinical Decision Rules

Validated clinical decision rules have been used to stratify the risk of VTE to determine whether to initiate diagnostic testing. The most widely validated rules are the Wells score for pulmonary embolism (PE) and deep venous thrombosis (DVT) and the Geneva score for PE. The Constans score has recently been validated for upper extremity DVT. The Wells score has been validated in inpatient and outpatient populations, whereas the Geneva score was validated only in an outpatient population and the Constans score was validated only in an inpatient population. No score has been validated in the assessment of recurrent VTE; therefore, diagnosis recommendations are based on expert opinion.


These recommendations assume that highly sensitive d-dimer results can be obtained in a timely manner and that the inconvenience and cost of d-dimer testing are acceptable to patients because additional diagnostic testing may be avoided. Suboptimal conditions may require repeat d-dimer testing. Use of age-adjusted d-dimer cutoffs in outpatients older than 50 years increases accuracy without an increase in harm.


The guideline panel used probability estimates, based on Wells scores, of 5% (low), 20% (intermediate), and 50% (high) as a basis for their recommendations for PE diagnosis.

For patients with low or intermediate risk, the guidelines recommend starting with a highly

Author disclosure: No relevant financial affiliations.

Coverage of guidelines from other organizations does not imply endorsement by AFP or the AAFP.

This series is coordinated by Sumi Sexton, MD, editor-in-chief.

A collection of Practice Guidelines published in AFP is available at



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