About This Page
This is a clinician-written, evidence-based guide aligned to the MCC Examination Objectives. It is structured by clinical presentation — the way the MCCQE tests and the way patients actually present. Management reflects current Canadian guidelines (CMA, CFPC, CPS). Always cross-reference with institutional protocols and clinical judgment.
The Bottom Line
- VTE workup is driven by pre-test probability: Wells/clinical gestalt first.
- D-dimer rules out VTE only in low or intermediate probability patients.
- DVT: unilateral leg swelling/pain; first-line imaging is compression ultrasound. PE: dyspnea, pleuritic chest pain, tachycardia or hypoxia; first-line imaging is usually CTPA.
- Massive PE with hypotension requires resuscitation, anticoagulation and consideration of thrombolysis or advanced therapy.
- Canadian practice commonly favours DOACs for most stable non-pregnant patients, with LMWH preferred in pregnancy and selected cancer/renal contexts.
Approach to the Presentation
Venous Thromboembolism (DVT / PE) is approached as a clinical presentation rather than as a single diagnosis. Begin by assessing stability, bleeding or thrombosis risk, infection/sepsis features, medication exposures, pregnancy status where relevant, and systemic red flags. Then use the pattern of the abnormality — CBC lineage, smear morphology, coagulation pathway, node distribution, spleen size, or VTE pre-test probability — to select focused investigations. For MCCQE1, the safest answer is usually the one that identifies must-not-miss disease while avoiding reflex treatment of an isolated laboratory value.
Differential Diagnosis
| diagnosis | likelihood | key features | distinguishing test |
|---|---|---|---|
| Massive pulmonary embolism | must-not-miss | Hypotension, syncope, severe dyspnea, tachycardia, hypoxia, elevated JVP, RV strain, VTE risk factors. | CTPA if stable; bedside echo/POCUS if unstable; ECG/troponin/BNP for risk stratification. |
| Proximal deep vein thrombosis | must-not-miss | Unilateral leg swelling, pain, pitting oedema, calf/thigh tenderness, surgery, immobility, cancer, pregnancy, estrogen. | Compression ultrasound of proximal veins; repeat if high suspicion and initial negative. |
| Cancer-associated thrombosis | must-not-miss | Unprovoked/recurrent VTE, weight loss, anaemia, thrombocytosis, known malignancy, migratory thrombophlebitis. | VTE imaging plus age-appropriate screening and targeted evaluation for red flags. |
| Pregnancy-associated VTE | must-not-miss | Pregnancy/postpartum dyspnea or unilateral leg symptoms; higher baseline D-dimer; left leg DVT common. | Compression ultrasound first for leg symptoms; PE imaging pathway with CTPA/VQ based on protocol. |
| Community-acquired pneumonia / pleurisy | common | Fever, cough, sputum, pleuritic pain, focal crackles; D-dimer may be elevated. | CXR and infection markers; PE imaging if probability remains significant. |
| Musculoskeletal leg pain or injury | common | Localized tenderness after exertion/trauma, no oedema or VTE risk factors. | Clinical assessment; ultrasound if DVT probability not low. |
| Cellulitis | common | Unilateral erythema, warmth, tenderness, fever, skin break; mimics DVT. | Clinical; ultrasound if swelling/risk factors/uncertainty. |
| Heart failure | common | Bilateral oedema, orthopnea, crackles, elevated JVP; PE may precipitate RV failure. | BNP, CXR, echo; VTE imaging if asymmetric signs or acute pleuritic symptoms. |
| Superficial thrombophlebitis | less common | Tender palpable cord along superficial vein, local erythema; extension risk near deep system. | Ultrasound if extensive, near saphenofemoral junction or risk factors. |
| Baker cyst rupture | less common | Posterior knee/calf pain and swelling, ankle bruising, arthritis history; mimics DVT. | Ultrasound showing cyst/rupture and excluding DVT. |
Red Flags & Key History
Symptoms
Syncope, hypotension, severe dyspnea or chest pain with shock — massive PE
Hemoptysis, pleuritic chest pain, tachycardia or hypoxia — PE features
Unilateral whole-leg swelling or calf asymmetry >3 cm — DVT features
Recent surgery, immobilization, hospitalization, long travel, cancer, prior VTE, estrogen therapy, pregnancy/postpartum
Active bleeding, recent intracranial haemorrhage or severe thrombocytopenia — anticoagulation risk
Fever and productive cough — pneumonia mimic but does not exclude PE
Signs
Hypotension, tachycardia, hypoxia, elevated JVP or RV heave
Unilateral pitting oedema, warmth or tenderness along deep veins
Signs of active bleeding before anticoagulation
Focal crackles or fever suggesting pneumonia
Palpable superficial cord
Approach to Investigation
First-line
Pre-test probability assessment (Wells or validated pathway)Determines whether D-dimer is appropriate; high probability proceeds to imaging and often empiric anticoagulation if safe.
D-dimerUse only in low/intermediate probability; false positives are common with age, pregnancy, cancer, infection and surgery.
Compression ultrasound for suspected DVTFirst-line imaging for symptomatic leg DVT.
CT pulmonary angiography for suspected PEFirst-line PE imaging in many Canadian settings if renal function and contrast tolerance allow.
Second-line
ECG, CXR, troponin/BNPHelps risk stratify PE and assess mimics; ECG may show sinus tachycardia or RV strain.
Bedside echo/POCUSIn unstable suspected PE, RV dilation/strain can support emergent management when CTPA is unsafe.
Baseline labs before anticoagulationCBC, creatinine/eGFR, liver tests, PT/INR/aPTT, pregnancy test where relevant.
Specialist
Thrombophilia testingNot routine in provoked VTE; consider selectively when results would change management.
Cancer evaluationAge-appropriate screening plus targeted workup for red flags; avoid indiscriminate whole-body imaging without clues.
Management Principles
Thrombosis Canada clinical guides + Choosing Wisely Canada recommendations1
Initial treatment
- If high clinical probability and bleeding risk is acceptable, start anticoagulation while awaiting imaging if delay is expected.
- Stable non-pregnant patients: DOAC such as apixaban or rivaroxaban when renal function and interactions permit.
- Pregnancy: LMWH is preferred; warfarin and most DOACs are avoided.
- Assess bleeding risk, renal function, interactions, weight extremes, antiphospholipid syndrome and cancer context.
2
PE risk stratification
- Massive PE with hypotension: resuscitate, anticoagulate and consider systemic thrombolysis or catheter/surgical therapy.
- Submassive PE with RV strain but stable BP: anticoagulation and close monitoring.
- Low-risk PE: outpatient treatment may be appropriate with stability, low bleeding risk and reliable follow-up.
3
Duration and prevention
- Provoked VTE by major transient factor: often 3 months of anticoagulation.
- Unprovoked, recurrent, persistent-risk-factor or cancer-associated VTE: consider extended therapy based on recurrence and bleeding risk.
- Educate on adherence, bleeding precautions, interactions and urgent return symptoms.
Complications & Pitfalls
- Do not order D-dimer after deciding probability is high.
- Do not forget pregnancy: pathways and anticoagulant choice differ.
- Do not over-test thrombophilia: provoked VTE usually does not need it.
- Assess bleeding before anticoagulation.
- PE can present as syncope.
MCCQE1 Exam Tips
- 1Estimate pre-test probability before D-dimer or imaging.
- 2Low Wells + negative D-dimer = VTE ruled out; high Wells = imaging, not D-dimer reassurance.
- 3Unstable suspected PE: bedside echo/POCUS can support urgent thrombolysis decisions.
- 4Provoked DVT after surgery usually needs finite anticoagulation; unprovoked/cancer-associated raises longer-term management.
- 5Choosing Wisely Canada: do not do thrombophilia testing after a first provoked DVT due to a known precipitant.
- 6DOACs are common first-line in stable non-pregnant VTE; LMWH is preferred in pregnancy.
practicetest your knowledge on venous thromboembolism (dvt / pe)Apply what you've learnt with MCCQE1-style questions from the iatroX Q-Bank — haematologic & oncologic and beyond.
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