Deep vein thrombosis

Wells score

• Active cancer (treatment ongoing, within 6 months, or palliative): 1 point

• Calf swelling where affected calf circumference measures >3 cm more than the asymptomatic calf (measured 10 cm below tibial tuberosity): 1 point

• Collateral superficial veins (non-varicose): 1 point

• Pitting oedema (confined to symptomatic leg): 1 point

• Swelling of entire leg: 1 point

• Localised pain along distribution of deep venous system: 1 point

• Paralysis, paresis, or recent plaster immobilisation of lower extremities: 1 point

• Recent bed rest for ≥3 days, or major surgery requiring regional or general anaesthetic within past 12 weeks: 1 point

• Previous history of DVT or pulmonary embolism: 1 point

• Alternative diagnosis at least as likely as DVT: subtract 2 points.

If the Wells score is ≥2, the patient is classified as ‘DVT likely' (absolute risk is approximately 40%).[107]Blann AD, Lip GY. Venous thromboembolism. BMJ. 2006 Jan 28;332(7535):215-9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1352055 http://www.ncbi.nlm.nih.gov/pubmed/16439400?tool=bestpractice.com [108]Scarvelis D, Wells PS. Diagnosis and treatment of deep-vein thrombosis. CMAJ. 2006 Oct 24;175(9):1087-92. http://www.cmaj.ca/cgi/content/full/175/9/1087 http://www.ncbi.nlm.nih.gov/pubmed/17060659?tool=bestpractice.com If the Wells score is <2 the patient is classified as ‘DVT unlikely’ (probability <15%).[15]National Institute for Health and Care Excellence. Venous thromboembolic diseases: diagnosis, management and thrombophilia testing. Aug 2023 [internet publication]. https://www.nice.org.uk/guidance/ng158 [107]Blann AD, Lip GY. Venous thromboembolism. BMJ. 2006 Jan 28;332(7535):215-9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1352055 http://www.ncbi.nlm.nih.gov/pubmed/16439400?tool=bestpractice.com [108]Scarvelis D, Wells PS. Diagnosis and treatment of deep-vein thrombosis. CMAJ. 2006 Oct 24;175(9):1087-92. http://www.cmaj.ca/cgi/content/full/175/9/1087 http://www.ncbi.nlm.nih.gov/pubmed/17060659?tool=bestpractice.com

[ Modified Wells score for deep vein thrombosis (DVT) Opens in new window ]

Ultrasonography criteria

The radiologist or technician who performs lower-extremity ultrasound first locates the femoral artery and vein in the groin region. The artery and its associated pulsatility can be identified readily; the femoral vein is adjacent. Inability to compress the vein indicates the presence of a clot, but provides no information on the age of the clot; further investigation with duplex or colour-flow doppler is needed.[121]Stone J, Hangge P, Albadawi H, et al. Deep vein thrombosis: pathogenesis, diagnosis, and medical management. Cardiovasc Diagn Ther. 2017 Dec;7(suppl 3):S276-84. https://pmc.ncbi.nlm.nih.gov/articles/PMC5778510 http://www.ncbi.nlm.nih.gov/pubmed/29399531?tool=bestpractice.com ​​

Criteria that suggest acuity of thrombosis have not been well-validated, and comparison with previous imaging is the most reliable method to exclude new from prior thrombosis.

All of the deep veins in the leg must be identified and compressed in a deliberate and systematic fashion (including the deep veins of the calf if whole-leg ultrasound is chosen). There must be a careful search for a duplicated femoral vein and a duplicated popliteal vein.

Secondary criteria include a larger vein diameter on the affected side, and absent or scant echoes within the clot. In acute DVT, the vein is non-compressible and dilated. In subacute DVT, the vein is non-compressible and marginally dilated or of normal size. In chronic DVT, the affected vein is non-compressible and small. Acute DVT is frequently easy to determine on the ultrasound, but where the vein is normal-sized or the vein is partially compressible or partially non-compressible, it is more difficult to determine the age of the DVT. In these cases, the DVT is referred to as age-indeterminate.