Investigation and Management of Deep Vein Thrombosis

Diagnosis of acute deep vein thrombosis (DVT)

Signs and symptoms which may accompany an acute DVT

Leg (or arm):

Swelling
Tenderness
Warmth
Pitting oedema
Erythema

In almost all suspected cases positive radiological confirmation will be required. However, for those presenting from the community it may be possible to rule out such a diagnosis by use of pre-test clinical probability scoring schemes in conjunction with measurement of D-dimer levels, which are almost invariably increased in cases of acute DVT.

N.B. D-dimer measurement is not useful in the diagnosis of VTE in pregnant women or already hospitalised patients and should not be measured in these patient groups. The use of D-dimer is not validated for use in upper limb DVT and its use should be avoided.

Figure 1- Suspected DVT Decision Algorithm

Possible DVT (use Wells clinical score, table 1 below)

↓

Wells clinical score <2 and D-dimer negative – DVT unlikely. Consider other diagnoses before discharge and issue patient information sheet.

Wells clinical score <2 and D-dimer positive – continue below

Wells clinical score ≥2 (irrespective of D-dimer) – continue below

↓

Treat as DVT until ultrasound result available.

Is patient suitable for outpatient management? If person who injects drugs (PWID), follow specific guidance available here.

Diagnostic algorithm for outpatients with suspected DVT

Numerous studies have confirmed that outpatient based treatment is safe and equally effective. Wider use of direct oral anticoagulants (DOACs) has further simplified treatment in the outpatient setting. Patients should be assessed if appropriate for outpatient management - please refer to the local protocol used at your hospital site.

Exclusion criteria

Active bleeding or at increased bleeding risk.
Recent stroke (in last 4-6 weeks).
Suspected bilateral DVTs.
Extremes of weight.
Renal impairment with creatinine clearance <30ml/minute.

Outpatients who have a negative ultrasound should discontinue anticoagulation and be considered for a repeat scan at 5–7 days if there is no likely alternative diagnosis for their leg symptoms. A repeat scan is not required if the patient's D-dimer was negative on initial testing (NICE guidance - Venous thromboembolic diseases: diagnosis, management and thrombophilia testing. 2023. [NG158]).

Wells Clinical Score

This score should be utilised in all NHSGGC hospitals when DVT is suspected in outpatients

Table 1: Wells Clinical Score

Wells Clinical Score	Score
Active cancer (treatment ongoing or within previous 6 months or palliative)	1
Paralysis, paresis, or recent plaster immobilisation of lower extremities	1
Recently bedridden for ≥3 days, or major surgery within 12 weeks	1
Localised tenderness along distribution of deep venous system	1
Entire leg swollen	1
Calf swollen by ≥3cm compared to asymptomatic leg (10cm below tibial tuberosity)	1
Pitting oedema (greater in symptomatic leg)	1
Collateral superficial veins (non-varicose)	1
Previously documented DVT	1
Alternative diagnosis as likely or greater than that of DVT	-2
TOTAL: Score <2: DVT unlikely Score ≥2: DVT possible

Wells PS, Anderson DR, Rodger M et al. Evaluation of D-Dimer in the Diagnosis of Suspected Deep-Vein Thrombosis. The New England Journal of Medicine. 349(13), 1227-35. Adapted with permission from the Author.

If DVT is not excluded by the above, or the patient is already hospitalised

Check baseline coagulation screen, FBC, U&Es and LFTs.
Unless contraindicated, commence anticoagulant therapy with low molecular weight heparin (LMWH) or apixaban - see here for details.
Arrange objective radiological imaging (e.g. compression ultrasound leg).

Back to main Diagnosis and Treatment of Venous Thromboembolism (VTE) guideline for general management, including VTE follow-up clinics.

Guideline reviewed: March 2026

Page updated: April 2026