PassFinals
Cardiovascular

Deep Vein Thrombosis

A DVT is a venous clot, usually in a leg vein, that can extend or embolise to cause PE; diagnose it with a validated pathway and treat confirmed proximal disease with anticoagulation.

In a nutshell

Suspect DVT with unilateral leg pain/swelling, but first screen for PE. Use the two-level Wells pathway: DVT-likely patients need urgent proximal-vein ultrasound; DVT-unlikely patients need D-dimer. Treat confirmed proximal DVT with anticoagulation for at least 3 months, then reassess recurrence and bleeding risk.

Classic presentation

Unilateral calf or thigh pain and swelling after a provoking factor, with no better explanation; always ask about PE symptoms.

Key points

  • Use the two-level DVT Wells score before testing: likely is 2 points or more; unlikely is 1 point or less.
  • DVT-likely: proximal leg-vein ultrasound urgently; if unavailable within 4 hours, give interim anticoagulation and scan within 24 hours.
  • DVT-unlikely: D-dimer first; a positive result leads to ultrasound, while a negative result can exclude DVT in the appropriate pathway.
  • A positive D-dimer does not diagnose DVT and is frequently raised in cancer, pregnancy, inflammation and after surgery.
  • Confirmed proximal DVT usually needs anticoagulation for at least 3 months; use current NICE/BNF/local protocol for drug and dose.
  • Pregnancy, active cancer, severe renal impairment, triple-positive APS and major bleeding risk require a modified/specialist pathway.
  • Do not routinely use IVC filters or compression stockings to prevent post-thrombotic syndrome.
  • Give PE and bleeding safety-netting before discharge.

First-line investigation

Two-level DVT Wells score followed by urgent proximal-leg-vein ultrasound or D-dimer according to probability.

Management

Screen for PE and phlegmasia

  • Breathlessness, pleuritic chest pain, haemoptysis, syncope or hypoxia triggers a PE pathway; cyanotic massively swollen limb needs emergency vascular review.1,3

Apply the Wells pathway

  • Use two-level Wells; DVT-likely patients need urgent proximal ultrasound and DVT-unlikely patients need D-dimer first.1,2

Anticoagulate if testing is delayed

  • If required imaging or D-dimer cannot be obtained within the NICE time frame, offer interim anticoagulation when safe and arrange the test promptly.1,4,6

Treat confirmed proximal DVT

  • Offer at least 3 months of anticoagulation; choose the agent with renal/hepatic function, cancer, pregnancy, APS, interactions, bleeding risk and patient preference in mind.1,4,5,6

Modify high-risk pathways

  • Pregnancy, active cancer, severe renal impairment, major bleeding risk and triple-positive APS require specialist anticoagulant selection.1,2

Review duration and safety

  • At 3 months reassess provocation, recurrence risk, bleeding risk and preference; provide PE, bleeding and adherence safety-netting.1,3

Exam traps

  • DVT symptoms are non-specific; cellulitis, ruptured Baker cyst, muscle injury and superficial thrombophlebitis are important mimics.
  • A negative initial ultrasound does not always end the pathway: follow the NICE D-dimer/repeat-scan route.
  • D-dimer excludes in the right low-probability pathway; it does not confirm DVT.
  • Do not extrapolate standard oral anticoagulant choices to pregnancy, severe renal impairment, active cancer or triple-positive APS.
  • Anticoagulation reduces embolic risk but does not instantly remove the clot; new chest symptoms still need emergency PE assessment.

Illustrations

Virchow's triadDiagram of the three overlapping mechanisms: stasis, endothelial injury and hypercoagulability, with example causes for each arm.PassFinals · original
Common femoral vein thrombus on ultrasoundTransverse greyscale ultrasound showing echogenic thrombus within the left common femoral vein, marked by the arrow, confirming proximal deep-vein thrombosis.James Heilman, MD, Wikimedia Commons · CC-BY-SA-3.0
Embolisation pathway from leg to lungDiagram tracing a thrombus fragment dislodging from a leg vein, travelling through the inferior vena cava and right heart, and lodging in a pulmonary artery.PassFinals · original
Unilateral leg swelling in deep-vein thrombosisClinical photograph showing marked unilateral swelling and erythema of the right lower leg compared with the unaffected side, a typical presentation of lower-limb deep-vein thrombosis.James Heilman, MD, Wikimedia Commons · CC-BY-SA-3.0

Key sources

  1. NICE NG158: Venous thromboembolic diseases: diagnosis, management and thrombophilia testing (Recommendations on suspected/confirmed DVT, anticoagulation, duration, cancer, pregnancy, thrombophilia and IVC filters)Published 26 Mar 2020 | Updated 2 Aug 2023
  2. NICE CKS: Deep vein thrombosis (UK primary-care diagnostic and management topic)
  3. NHS: DVT (deep vein thrombosis) (Symptoms, urgent PE safety-netting, treatment and recovery information)
  4. BNF: Apixaban (Current anticoagulant prescribing, cautions and interactions)
  5. BNF: Rivaroxaban (Current anticoagulant prescribing, cautions and interactions)
  6. BNF: Enoxaparin sodium (Current LMWH prescribing, cautions and renal considerations)
  7. NICE NG158: Venous thromboembolic diseases — overview (Current guideline page and update status)Published 26 Mar 2020 | Updated 2 Aug 2023

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.