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First / New DVT Glos Care Pathway Overview

What's New - 2019?

The key aspects of the pathway are now as follows:

  • DO NOT need a D-dimer assay done because the new whole leg scans are considered to be a definitive test (current local guidance).
  • Anti-coagulate the patient using a method appropriate for them.
  • Request a ‘Whole lower limb DVT screening USS’. Make sure that you note the method of anticoagulation on the ICE scan request.

  • Check the patient’s D-dimer level prior to requesting a scan. Do not request a scan until you have the D-dimer result (see below). Practices participating in the point-of-care testing trial can now perform these at source but should send a parallel test sample to the labs as well.
  • Issue a prescription to the patient for an appropriate anticoagulant and advise them that they will receive a telephone call if they need to start it.

IMPORTANT: Include your anticoagulation plans AND the patient contact phone number in the ICE D-dimer request.

  • The labs will contact the requesting practice in-hours or the OOH service if out-of-hours. The patient should be contacted by a GP and instructed to start their anticoagulant.
  • The in-hours requesting GP should request a lower limb US scan via ICE. IMPORTANT: Include any anti-coagulation plans in the ICE scan request.

Please click the relevant flowchart box to be taken directly to textual information.



Red Flags
1. VTE during pregnancy and the puerperium (6 weeks post-partum).
2. VTE in IV drug users.
3. If you suspect DVT, always assess the patient for pulmonary embolism (PE) as well.
4. Apparently isolated superficial femoral vein thrombosis is frequently associated with femoral DVT, particularly when very proximal in thigh.
5. Upper Limb DVT - Follow AEC Pathway

A diagnosis of DVT is usually suspected in patients who complain of a painful swollen limb. However, the clinical picture can vary widely and none of the clinical features are sufficiently specific to be a diagnostic. Less than a third of patients referred for tests after initial history and clinical examination prove to have a DVT.

  • Pain or tenderness of the leg
  • Swelling of calf or leg
  • Pitting oedema
  • Palpable venous thrombosis
  • Increased temperature in the leg
  • Fever
  • Discoloration or erythema of the leg
  • Venous distension

  • Recent surgery
  • Recent injury or trauma
  • Previous DVT
  • Intravenous drug misuse
  • Recent immobility (> 24 hours)
  • Long haul air flight
  • Obesity or excess weight
  • Oestrogen therapy
  • Underlying malignant disease
  • Family history of thrombosis
  • Known thrombophilic defect
  • Pregnancy
Differential Diagnosis

Only about a third of people with clinical suspicion of deep vein thrombosis (DVT) have the condition. Other conditions which may present with similar signs and symptoms include:

  • Calf muscle tear or strain.
  • Haematoma (collection of blood) in the muscle.
  • Sprain or rupture of the Achilles tendon.
  • Fracture.

  • Superficial thrombophlebitis — see the CKS topic on Thrombophlebitis - superficial.
  • Post-thrombotic syndrome — see the CKS topic on Leg ulcer - venous.
  • Venous obstruction or insufficiency, or external compression of major veins (for example by a fetus during pregnancy, or cancer).
  • Arteriovenous fistula and congenital vascular abnormalities.
  • Acute limb ischaemia.
  • Vasculitis.
  • Heart failure — see the CKS topic on Heart failure - chronic.

  • Ruptured Baker's cyst (a Baker's cyst forms behind the knee from an out-pouching of the synovial membrane of the knee joint, and is a common complication of arthritis) — see the CKS topic on Baker's cyst.
  • Cellulitis (commonly mistaken as DVT) — see the CKS topic on Cellulitis - acute.
  • Dependent (stasis) oedema.
  • Lymphatic obstruction.
  • Septic arthritis.
  • Cirrhosis.
  • Nephrotic syndrome.
  • Compartment syndrome.
Primary Care Assessment

  • All patients presenting with suspected DVT should be assessed using a 2 level Wells Clinical Probability Scoring Tool.
  • If both legs are affected, score the more severe leg.
  • If suspected DVT, actively exclude a PE (if necessary using the two-level PE Wells score).
  • If PE likely, refer via SPCA to AEC

  • Anticoagulate with DOAC or LMWH
    Provide sufficient medication to treat until USS result available
  • Check U+E and a FBC
  • Consider checking clotting screen if history of bleeding or planning to use warfarin
  • Request USS via ICE

USS Positive

  • Diagnose DVT
  • Continue DOAC / Start Warfarin
  • Further assessment for underlying causes if unprovoked DVT

USS Negative

  • Discontinue treatment

  • Check U+E and a FBC
  • Consider checking clotting screen if history of bleeding or planning to use warfarin
  • Consider doing a D-dimer and give prescription for anticoagulant – patient to take if positive D-dimer
  • Arrange USS via ICE if D-dimer positive


D-dimers are a specific breakdown product of cross-linked fibrin, released during clot dissolution or fibrinolysis. The main object of the D-dimer test is to detect situations of thrombin activation and in vivo fibrin formation. Venous thrombotic embolism results in raised levels of D-dimers. The specificity of the assays for DVT is variable and depends on the patient population.

False negative D-dimer readings can occur if a sample is taken:

  1. Too soon after thrombus formation
  2. Too long after thrombus formation (D-dimer levels can be normal by day 7)
  3. In patients taking anti-coagulants including warfarin or DOACs such as Dabigatran and rivaroxaban because these inhibit thrombus extension

False positive readings can arise in a number of situations including:

  1. Healthy subjects: pregnancy, smoking and advancing age
  2. Chronic conditions: Atrial fibrillation, many cancers including lung, prostate, cervical and colorectal, liver disease
  3. Acute illnesses including infection
  4. Inflammation, including a high rheumatoid factor or vasculitis
  5. Severe systemic illnesses (only 80% of critically ill patients admitted to hospital with sever infection, inflammation disorders, DIC, trauma or sickle-cell crisis will have an abnormal D-dimer level)
  6. Cardiac conditions including ACS and unstable angina
  7. Trauma and recent surgery
  8. Severe superficial phlebitis

VTE risk rises with D-dimer concentration because large clots produce more D-dimer. This is worth bearing in mind when evaluating false positive D-dimers results.

Note that a D-dimer test can become negative two weeks after a clot occurs, so all patients with possible DVT who have had symptoms for two weeks or more must be scanned.

Management (Primary Care and Community)
  1. Advise re. duration of treatment and monitoring if on Warfarin
  2. Advice:
    a. Regular walking
    b. Elevation of leg (supported at heel) when sitting
    c. Good hydration
    d. Avoid venous obstruction
    e. Extended travel or travel by aeroplane should be delayed with at least 2 weeks after starting anticoagulant treatment

Key Point
Patients with a diagnosed unprovoked DVT will need further assessment for a possible underlying cause.

  1. If over 40 years of age - always investigate for cancer
  2. If without cancer –  consider test for antiphosphlipid antibodies before stopping anticoagulation treatment at 3 months
  3. If aged 45 years or under and there is a 1st degree relative who has had DVT or PE, consider test for hereditary thrombophilia. But thrombophilia testing is rarely indicated or helpful (BMJ Diagnosis and Management of Heritable Thrombophilias)

  1. History taking reviewing for any red flag symptoms, ensuring relevant National Screening Programme invitations have been taken up (mammography, cervical smear and bowel scope/ FOB kits)
  2. Physical examination with consent including breast examination, for lymphadenopathy, rectal including prostate examination
  3. Urine dip and bloods including FBC, LFTs Ca, consider PSA
  4. CXR in smokers or ex-smoker
  5. If there are significant concerns consider abdominopelvic CT scan (+ mammogram for women)

Duration of anticoagulation
Treat for 3 months then reassess need for ongoing treatment e.g. recurrent DVT or persistent risk factors such as cancer.

Read Codes

Clinical Term

Read Code V2

Additional Notes (if applicable)

Read Code V3


Suspected deep vein thrombosis (DVT)


Suspected DVT



Wells deep vein thrombosis clinical probab


Wells clinical assessment tool



D-dimer level


D-dimer test



Venogram normal


Venogram normal



Venogram abnormal


Venogram abnormal



Deep vein phlebitis and thrombophlebitis of the leg


DVT diagnosis code



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