Diagnosis and Treatment of Venous Thromboembolism

Introduction

Fifty percent of Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE) arise spontaneously, without any obvious triggering event; there are many risk factors which are particularly common in hospitalised patients.

Early recognition and treatment of an acute venous thromboembolism (VTE) is essential to reduce the risk of early fatal PE. It is estimated that deaths from healthcare-associated PE far exceed those from healthcare-associated infection.

The treatment pathway for acute VTE is outlined below. Information specific to the investigation and management of PE or DVT can be found by following the relevant links below:

• Investigation and Management of PE
• Investigation and Management of DVT

Diagnosis of acute VTE

• Signs and symptoms which may accompany an acute DVT or PE include:
  • Calf warmth, tenderness, swelling, pitting oedema, erythema
  • Chest pain (often pleuritic), cyanosis, breathlessness, haemoptysis, collapse
  • Tachycardia / hypotension, raised JVP, hypoxia, tachypnoea
• Positive radiological confirmation will be required in almost all suspected cases.
• If presenting from the community it may be possible to rule out 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 VTE.
• 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.

If DVT / PE 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 either apixaban or low molecular weight heparin (LMWH) – see Drug therapy / treatment options.
• Arrange objective radiological imaging (e.g. compression ultrasound leg or CTPA chest or V/Q lung scan).

General Management

A duration of 3 to 6 months of therapeutic anticoagulation should be sufficient for most patients (longer term anticoagulation should be considered for those who have had recurrent thrombosis or are considered at high risk of a recurrent event). Treatment duration can be discussed at follow-up clinic.

For details of anticoagulation choice, dosage and administration see the Drug therapy / treatment options section. 

Special cases where management may differ

Pregnant patients

Both diagnostic and management strategies differ (see the NHSGGC guideline Thromboembolic Disease during Pregnancy and the Puerperium).

Patients with active cancer

Patients with active malignancy and/or receiving systemic anti-cancer therapy (SACT) / radiotherapy who are diagnosed with VTE should be started on a therapeutic dose of apixaban or LMWH. Seek advice and discuss with patient and their cancer team. Refer to the NHSGGC guideline Treatment and Secondary Prophylaxis of Venous Thrombosis in Patients with Malignant Disease for further information. 

Patients with superficial thrombophlebitis

Some patients with extensive superficial thrombophlebitis proximal to the knee can be considered for 40 days of anticoagulation with rivaroxaban (off-label use) oral 10mg once daily (prophylactic dose). See NHSGGC guideline on Thrombophlebitis, superficial, secondary care, adults (excluding pregnancy) for further information.

People who inject drugs

• Given their chaotic lifestyles and habits, these patients may be considered at high risk of bleeding complications from therapeutic anticoagulant therapy, particularly warfarin therapy which demands careful compliance with monitoring and avoidance of interacting drugs (including alcohol).
• For these patients, an individualised risk / benefit assessment is required to decide whether to treat with an anticoagulant or not.
• See the NHSGGC guideline on Outpatient Management of Person who Injects Drugs (PWID) with suspected deep vein thrombosis (DVT) for further information, including details of treatment for related conditions (e.g. cellulitis).

Screening for cancer in patients with unprovoked venous thrombosis

Investigation for occult malignancy in unprovoked VTE, in patients over 40 years old, should involve full clinical history and examination, basic laboratory testing, chest x-ray, urinalysis and any age-appropriate cancer screening if not already performed. Routine extensive screening is not recommended. Rather, investigation for occult malignancy in VTE should be directed by, and be appropriate to, clinical signs and symptoms presented at diagnosis.

Thrombophilia testing

Thrombophilia testing is warranted in some patients who experience a VTE but should not be performed at the time of the acute event or during anticoagulation therapy.

VTE follow-up clinics

Ideally all acute VTE patients should be considered for follow up in a dedicated clinic for review, further investigations (if needed) and discussion of treatment duration.

In GGC, clinics run on various acute sites, with patients initially discussed in a Thrombosis Multi-disciplinary team (MDT) where possible. Check the local pathway for your site. Ensure there is a clear plan and follow up for the patient prior to discharge.

Guideline last reviewed: March 2026

Page updated: April 2026