diagnosis of DVT

Last edited 04/2018 and last reviewed 07/2021

If a patient presents with signs or symptoms of deep vein thrombosis (DVT), carry out an assessment of their general medical history and a physical examination to exclude other causes (1).

If DVT is suspected, two-level Wells Clinical Prediction Rule could be used to assess the probability of a DVT (1)

• if the patient had a “likely” two-level DVT Wells (score >=2) then offer either:
• a proximal leg vein ultrasound scan - this should be undertaken within 4 hours of being requested and, if the result is negative, then a D-dimer test should be calculated

OR

• a D-dimer test and an interim 24-hour dose of a parenteral anticoagulant (if a proximal leg vein ultrasound scan cannot be carried out within 4 hours) and a proximal leg vein ultrasound scan carried out within 24 hours of being requested.
• repeat the proximal leg vein ultrasound scan 6–8 days later for all patients with a positive D‑dimer test and a negative proximal leg vein ultrasound scan
• if the patient had a “unlikely” two-level DVT Wells score (score ≤1), then undertake a D-dimer test and if the result is positive offer either:
• a proximal leg vein ultrasound scan carried out within 4 hours of being requested OR
• an interim 24-hour dose of a parenteral anticoagulant (if a proximal leg vein ultrasound scan cannot be carried out within 4 hours) and a proximal leg vein ultrasound scan carried out within 24 hours of being requested

An alternative diagnosis should be considered in the following situations:

• an “unlikely” two‑level DVT Wells score and
• a negative D‑dimer test OR
• a positive D‑dimer test and a negative proximal leg vein ultrasound scan.
• a “likely” two‑level DVT Wells score AND
• a negative proximal leg vein ultrasound scan and a negative D‑dimer test OR
• a repeat negative proximal leg vein ultrasound scan

Advise patients in these two groups that it is not likely they have DVT, and discuss with them the signs and symptoms of DVT and when and where to seek further medical help (1)

Reference:

• (1) National Institute for Health and Care Excellence (NICE) 2015. Venous thromboembolic diseases: diagnosis, management and thrombophilia testing