Venous thromboembolism

On this page

Quick Overview

Venous thromboembolism (VTE) encompasses deep vein thrombosis (DVT) and pulmonary embolism (PE), affecting ~1-2/1000 annually in the UK. NICE NG158 (2020) provides evidence-based guidance on diagnosis, anticoagulation choice, and duration. Rapid risk stratification using Wells score and appropriate D-dimer interpretation prevents both missed diagnoses and unnecessary imaging.

Core Facts & Concepts

Wells Score for DVT (≥2 = DVT likely, <2 = DVT unlikely):

  • Active cancer (+1), paralysis/immobilization (+1), bedridden >3 days/major surgery within 12 weeks (+1)
  • Localized tenderness along deep veins (+1), entire leg swollen (+1)
  • Calf swelling >3cm vs asymptomatic leg (+1), pitting oedema (+1)
  • Collateral superficial veins (+1), alternative diagnosis as likely (-2)

Wells Score for PE (>4 = PE likely, ≤4 = PE unlikely):

  • Clinical DVT signs (+3), PE most likely diagnosis (+3), heart rate >100 (+1.5)
  • Immobilization/surgery in previous 4 weeks (+1.5), previous VTE (+1.5)
  • Haemoptysis (+1), malignancy (+1)

Figure 1: Doppler ultrasound showing non-compressible femoral vein with echogenic thrombus

D-dimer Interpretation:

  • Use only if Wells score = "unlikely" (negative predictive value >99%)
  • Age-adjusted threshold: age × 10 μg/L if >50 years (improves specificity)
  • 📊 False positives: pregnancy, malignancy, infection, post-operative, elderly

Anticoagulation per NICE NG158:

  • First-line: Apixaban or Rivaroxaban (DOACs) - no monitoring required
  • Alternative DOACs: Edoxaban or Dabigatran (require initial LMWH for ≥5 days)
  • Warfarin: Use if DOACs contraindicated (renal failure CrCl <15, antiphospholipid syndrome)

Figure 2: CT pulmonary angiogram showing filling defect in right pulmonary artery

Problem-Solving Approach

Step-by-step VTE diagnosis:

  1. Calculate Wells score - determines imaging pathway
  2. If "unlikely": D-dimer → negative = stop; positive = imaging
  3. If "likely": Proceed directly to imaging (DVT: compression USS; PE: CTPA)
  4. Interim anticoagulation: Start immediately if imaging delayed >4 hours

Anticoagulation Duration (NICE NG158):

  • Provoked VTE (surgery, trauma, oestrogen, pregnancy): 3 months
  • Unprovoked VTE: 3-6 months, then reassess bleeding vs recurrence risk
  • Active cancer: 3-6 months (consider extended with LMWH or DOAC)
  • Recurrent unprovoked VTE: Consider lifelong anticoagulation

🚩 Red Flags for Extended Anticoagulation: Unprovoked proximal DVT/PE, recurrent VTE, antiphospholipid syndrome, active cancer

Thrombophilia Screening Indications (NICE NG158 does NOT routinely recommend):

  • Consider only if: age <50, recurrent VTE, unusual site (mesenteric, cerebral), strong family history
  • Tests: Factor V Leiden, Prothrombin G20210A, Protein C/S, Antithrombin, Antiphospholipid antibodies

Analysis Framework

FeatureDOAC (Apixaban/Rivaroxaban)Warfarin
Onset2-4 hours48-72 hours (requires heparin bridge)
MonitoringNoneINR target 2-3 (weekly then monthly)
Renal dosingAvoid if CrCl <15Safe in severe renal failure
ReversalIdarucizumab (dabigatran), Andexanet alfa (Xa inhibitors)Vitamin K, PCC
Drug interactionsFewerMultiple (antibiotics, antifungals)
PregnancyContraindicatedTeratogenic (use LMWH)
APSContraindicatedFirst-line

DOAC vs Warfarin Selection:

  • DOAC preferred unless: severe renal failure (CrCl <15), antiphospholipid syndrome, mechanical heart valves
  • Warfarin if patient preference for monitoring or concerns about adherence/cost

Visual Aid

Key Points Summary

Wells score determines pathway: "Unlikely" = D-dimer first; "Likely" = direct imaging (DVT: USS, PE: CTPA)

Age-adjusted D-dimer (age × 10 μg/L if >50 years) reduces false positives in elderly without missing VTE

NICE NG158 first-line: Apixaban or Rivaroxaban (no monitoring); reserve warfarin for CrCl <15 or antiphospholipid syndrome

Duration: Provoked = 3 months; Unprovoked = 3-6 months then reassess; Cancer/recurrent = consider extended

Thrombophilia screening NOT routine - only if age <50, recurrent VTE, unusual site, or strong family history

Interim anticoagulation: Start immediately if imaging delayed >4 hours (prevents clot extension)

Common pitfall: Using D-dimer in "likely" Wells score or high pre-test probability (leads to false reassurance if negative)

Practice Questions: Venous thromboembolism

Test your understanding with these related questions

A 52-year-old woman presents with progressive dysphagia and weight loss. She has tight skin on her hands and face. ANA shows nucleolar pattern. What is the most concerning systemic complication?

1 of 5

Flashcards: Venous thromboembolism

1/10

D-Dimer is a marker of _____

TAP TO REVEAL ANSWER

D-Dimer is a marker of _____

fibrin degredation

browseSpaceflip

Enjoying this lesson?

Get full access to all lessons, practice questions, and more.

Start Your Free Trial