Clinical Practice Guideline

Diagnosis of Venous Thromboembolism - Clinical Practice Guideline

Diagnosis of Venous Thromboembolism

(Endorsed, March 2019)

The guideline on Diagnosis of Venous Thromboembolism was developed by the American Society of Hematology and was endorsed by the American Academy of Family Physicians.  

Key Recommendations

Pulmonary Embolism (PE)

  • For individuals with a low or intermediate pretest probability or prevalence, clinicians should use a D-dimer strategy to rule out PE followed by VQ scan or CTPA in patients requiring additional testing. D-dimer testing alone should not be used to rule in a PE.

  • For individuals with a high pretest probability or prevalence (≥50%), clinicians should start with CTPA to diagnose PE. If CTPA is not available, a VQ scan be used with appropriate follow up testing.

  • D-dimer testing alone should not be used to diagnose PE and should not be used as a subsequent test after CT scan in individuals with a high pretest probability/prevalence.

  • For individuals who have a positive D-dimer or likely pretest probability, a CTPA should be performed. D-dimer testing can be used to exclude recurrent PE in individuals with unlikely pretest probability.

  • Use of an age-adjusted D-dimer cutoff in outpatients older than 50 years is safe and improves diagnostic yield. Age-adjusted cutoff = Age (years) x 10 µg/L (using D-dimer assays with a cutoff of 500 µg/L).

Lower Extremity Deep Vein Thrombosis (DVT)

  • For individuals with a low pretest probability or prevalence, clinicians should use a D-dimer strategy to rule out DVT followed by proximal lower extremity ultrasound or whole-leg ultrasound in patients requiring additional testing.

  • For individuals with low pretest probability or prevalence (≤10%), positive D-dimer alone should not be used to diagnose DVT and additional testing following negative proximal or whole-leg ultrasound should not be conducted.

  • For individuals with an intermediate pretest probability or prevalence (~25%), whole-leg ultrasound or proximal lower extremity ultrasound should be used. Serial proximal ultrasound testing is needed after a negative proximal ultrasound. No serial testing is needed after a negative whole leg ultrasound.

  • For individuals with suspected DVT and high pretest probability or prevalence (≥50%), whole-leg ultrasound or proximal lower extremity ultrasound should be used. Serial ultrasound should be used if initial ultrasound is negative and no alternative diagnosis is identified.

Upper Extremity DVT

  • For individuals with low prevalence/unlikely pretest probability, D-dimer testing should be used to exclude upper extremity DVT, followed by duplex ultrasound if positive.

  • For individuals with high prevalence/likely pretest probability, either D-dimer testing followed by duplex ultrasound/serial duplex ultrasound, or duplex ultrasound/serial duplex ultrasound alone can be used for assessing patients suspected of having upper extremity DVT.

  • A positive D-dimer alone should not be used to diagnose upper extremity DVT.

See the full recommendation for more information. 


These guidelines are provided only as assistance for physicians making clinical decisions regarding the care of their patients. As such, they cannot substitute the individual judgment brought to each clinical situation by the patient’s family physician. As with all clinical reference resources, they reflect the best understanding of the science of medicine at the time of publication, but they should be used with the clear understanding that continued research may result in new knowledge and recommendations. These guidelines are only one element in the complex process of improving the health of America. To be effective, the guidelines must be implemented.