Internal Medicine · Year 3 · from Internal Medicine

Case 3: Unprovoked VTE and Thrombophilia Evaluation

Patient Presentation

A 32-year-old woman presents with acute left leg swelling and is diagnosed with extensive iliofemoral DVT. She has no recent travel, surgery, immobilization, or hormone use. She is otherwise healthy with no medical history. Her mother had a DVT at age 40, and her maternal grandmother died of a "blood clot in the lungs" at age 55.

Vital Signs

  • Blood Pressure: 118/72 mmHg
  • Heart Rate: 78 bpm
  • Respiratory Rate: 14/min
  • Oxygen Saturation: 99% on room air

Physical Examination

  • General: Well-appearing
  • Left lower extremity: Swelling, erythema from ankle to groin
  • Otherwise normal examination

Imaging

  • Duplex ultrasound: Extensive thrombus in left external iliac, common femoral, and femoral veins

Clinical Image

Figure 3: Doppler ultrasound showing extensive iliofemoral deep vein thrombosis with absent flow in the common femoral vein and visualized echogenic thrombus.

Image Source: Educational illustration for teaching purposes.

Questions

  1. What features of this case suggest inherited thrombophilia?
  • A) Age >65
  • B) Young age (<50), unprovoked VTE, strong family history of VTE
  • C) Recent surgery
  • D) Presence of cancer
  1. When should thrombophilia testing be performed?
  • A) During acute thrombosis on anticoagulation
  • B) After completing anticoagulation therapy, typically 2-4 weeks after stopping
  • C) Before starting anticoagulation
  • D) Testing is never indicated
  1. What inherited thrombophilias should be tested for?
  • A) Factor V Leiden only
  • B) Factor V Leiden, prothrombin G20210A mutation, antithrombin deficiency, protein C and S deficiency
  • C) All clotting factors
  • D) Only acquired conditions
  1. How does diagnosis of thrombophilia affect management?
  1. What is the recommended duration of anticoagulation for unprovoked proximal DVT?

Answers

  1. B) Young age (<50), unprovoked VTE, strong family history of VTE - Features suggesting inherited thrombophilia:
  • Age <50 years at first VTE
  • Unprovoked (idiopathic) VTE
  • Strong family history (first-degree relatives with VTE)
  • Recurrent VTE
  • VTE at unusual sites (cerebral, splanchnic, upper extremity)
  • Warfarin-induced skin necrosis (protein C/S deficiency)
  1. B) After completing anticoagulation therapy, typically 2-4 weeks after stopping - Testing timing:
  • Acute thrombosis and anticoagulation affect results
  • Warfarin decreases protein C and S
  • Heparin decreases antithrombin
  • DOACs can affect lupus anticoagulant testing
  • Wait 2-4 weeks after stopping anticoagulation for accurate results
  • Testing rarely changes acute management
  1. B) Factor V Leiden, prothrombin G20210A mutation, antithrombin deficiency, protein C and S deficiency - Standard thrombophilia panel:
  • Factor V Leiden mutation (most common)
  • Prothrombin G20210A mutation
  • Antithrombin deficiency
  • Protein C deficiency
  • Protein S deficiency
  • Also consider: Antiphospholipid antibodies (acquired), homocysteine
  1. How thrombophilia diagnosis affects management:
  • Does NOT change acute treatment (still anticoagulate)
  • May influence duration of anticoagulation (extended/indefinite for high-risk thrombophilias)
  • Informs family screening and counseling
  • Guides risk assessment for future events (surgery, pregnancy, estrogen use)
  • Antithrombin deficiency and antiphospholipid syndrome have highest recurrence risk
  • Heterozygous Factor V Leiden has relatively low recurrence risk
  1. Duration of anticoagulation for unprovoked proximal DVT:
  • Minimum 3 months
  • After 3 months, assess for extended therapy
  • Extended anticoagulation (indefinite) generally recommended for unprovoked proximal DVT if bleeding risk acceptable
  • Use risk assessment tools (HERDOO2, DASH score) to guide decision
  • If extended therapy chosen, consider reduced-dose DOAC (apixaban 2.5 mg BID, rivaroxaban 10 mg daily) after initial 6 months
  • Annual reassessment of risk-benefit

Learning Points

  1. Wells criteria help stratify pretest probability for DVT and PE; guide appropriate use of D-dimer and imaging.
  1. D-dimer has high negative predictive value; negative D-dimer in low/moderate probability effectively excludes VTE.
  1. DOACs are preferred for most VTE; LMWH remains important for cancer-associated thrombosis (especially GI cancers).
  1. PE risk stratification (massive, submassive, low-risk) guides treatment intensity; thrombolysis reserved for hemodynamic instability.
  1. Unprovoked VTE warrants consideration of extended anticoagulation and, in select cases, thrombophilia testing.

All cases for this lecture as Markdown