Venous thromboembolism (DVT and PE): the Australian GP framework

VTE — DVT and PE in Australian general practice

Venous thromboembolism (VTE) — encompassing deep vein thrombosis (DVT) and pulmonary embolism (PE) — affects approximately 1–2 per 1,000 Australian adults per year, rising to approximately 10 per 1,000 over 80. Annual PE-related mortality in Australia is estimated at 5,000–7,000 deaths. Hospital-acquired VTE accounts for approximately 30% of all VTE events, making inpatient prophylaxis an important parallel domain.

The GP’s role in VTE spans pre-test probability assessment, triage for urgent imaging, anticoagulant initiation or coordination, duration decisions, and long-term monitoring in patients on extended anticoagulation. The Thrombosis and Haemostasis Society of Australia and New Zealand (THANZ) 2019 guidelines and THANZ 2025 DOAC practical guidance are the primary Australian references, supplemented by eTG Cardiovascular and AMH.

Recognise massive PE immediately: systolic BP <90 mmHg, syncope, severe hypoxia, or signs of RV strain in a patient with pleuritic chest pain or breathlessness = activate the emergency response. Massive PE carries 30–50% in-hospital mortality without immediate treatment. Call 000 — do not delay for investigations.

A. Core clinical — the AU general-practice framework

Pre-test probability — the Wells scores

Clinical pre-test probability must be established before D-dimer or imaging, per THANZ 2019 and eTG:

Wells DVT score (Wells NEJM 1997):

Criterion	Points
Active cancer	1
Paresis or recent plaster immobilisation of lower limb	1
Recent immobilisation >3 days or major surgery within 12 weeks	1
Tenderness along deep venous system	1
Entire leg swollen	1
Calf swelling >3 cm compared with contralateral leg	1
Pitting oedema (symptomatic leg only)	1
Collateral superficial veins (non-varicose)	1
Prior documented DVT	1
Alternative diagnosis as likely or more likely than DVT	−2

Score ≤1 = DVT unlikely; ≥2 = DVT likely.

Wells PE score — includes clinical DVT signs (+3), PE most likely diagnosis (+3), heart rate >100 (+1.5), immobilisation/surgery in past 4 weeks (+1.5), prior DVT/PE (+1.5), haemoptysis (+1), malignancy (+1). Score ≤4 = PE unlikely; >4 = PE likely.

The YEARS algorithm (van der Hulle Lancet 2017) uses 3 items (clinical DVT signs, haemoptysis, PE most likely diagnosis) combined with D-dimer thresholds to safely reduce CTPA by approximately 14%.

D-dimer — appropriate and inappropriate use

eTG and THANZ 2019 are explicit: D-dimer (MBS 65129) is a rule-out test in low pre-test probability only. A negative D-dimer in a low-probability patient safely excludes VTE without imaging.

Age-adjusted D-dimer (age × 10 ng/mL for patients over 50) improves specificity without losing sensitivity (van Es BMJ 2013).

Critical safety point: Never use D-dimer to exclude VTE in a patient with high clinical pre-test probability. Image regardless of D-dimer result in those patients.

Imaging

• Compression ultrasound (CUS) — first-line for DVT; MBS 55244. Whole-leg or proximal-only with serial repeat at 1 week for isolated calf suspicion
• CTPA — first-line for PE, sensitivity and specificity approximately 95% (PIOPED II NEJM 2006); MBS 57350 range
• V/Q scan — preferred in pregnancy (lower breast radiation), severe contrast allergy, CKD eGFR <30, young patients with no underlying lung disease
• Echocardiogram — haemodynamic stratification of PE; RV dilatation and McConnell’s sign indicate significant RV strain

Differential diagnosis

DVT mimics: cellulitis (fever, follows lymphatics), ruptured Baker’s cyst (sudden posterior pain, may have ecchymosis), muscle strain or haematoma, lymphoedema, post-thrombotic syndrome.

PE mimics: acute coronary syndrome, pericarditis, pneumonia, pleurisy, pneumothorax, asthma or COPD exacerbation, panic attack, aortic dissection.

B. Anticoagulant choice — the DOAC era

Per THANZ 2019/2025 and eTG, DOACs are first-line for most adults with VTE:

Drug	Acute phase	Maintenance	Extended (>6 months)	Avoid if
Apixaban	10 mg twice daily × 7 days	5 mg twice daily	2.5 mg twice daily	CrCl <25
Rivaroxaban	15 mg twice daily with food × 21 days	20 mg daily with food	10 mg daily	CrCl <15
Dabigatran	LMWH ≥5 days, then 150 mg twice daily	Same	—	CrCl <30
Warfarin	LMWH bridge to INR 2–3 × 2 consecutive days	INR 2–3	Same	Preferred in APLS triple-positive, mechanical heart valve

Why DOACs over warfarin: The AMPLIFY trial (Agnelli NEJM 2013) and EINSTEIN trials (NEJM 2010/2012) established non-inferior efficacy with significantly reduced major bleeding (especially intracranial haemorrhage) and no requirement for INR monitoring. No LMWH bridging is needed with apixaban or rivaroxaban — start directly.

Important exceptions:

• Cancer-associated VTE: LMWH historically gold-standard; apixaban non-inferior with similar bleeding per CARAVAGGIO (NEJM 2020); avoid DOAC in active GI or GU cancer with high bleeding risk
• APLS triple-positive (LAC + aCL + β2GP1): warfarin is preferred; the TRAPS trial (Pengo NEJM 2018) showed rivaroxaban inferior to warfarin for thrombotic recurrence in high-risk APLS
• Pregnancy: LMWH only (enoxaparin 1 mg/kg twice daily or 1.5 mg/kg once daily); DOACs cross the placenta; warfarin is teratogenic in first trimester; switch to unfractionated heparin peripartum
• Mechanical heart valves: warfarin only — DOACs are contraindicated

C. Duration of anticoagulation and extended therapy

Duration framework

Per THANZ 2019 and eTG:

Scenario	Duration
Distal DVT with major transient provocation	6 weeks
Proximal DVT or PE with major surgical provocation	3 months
Non-surgical transient provocation	3–6 months
Hormonal provocation (OCP, HRT, pregnancy/postpartum)	3–6 months + cease trigger
Unprovoked first event	≥6 months; consider extended indefinite at reduced dose
Recurrent unprovoked	Indefinite
Active cancer	Indefinite while cancer or treatment active
APLS triple-positive	Indefinite (warfarin)

Extended therapy at reduced DOAC dose: AMPLIFY-EXT (NEJM 2013) and EINSTEIN-CHOICE (NEJM 2017) confirmed that reduced-dose apixaban (2.5 mg twice daily) and rivaroxaban (10 mg daily) maintain efficacy with low bleeding rates beyond 6 months. Recurrence risk after unprovoked VTE is approximately 10% at 1 year and 30% at 10 years — the argument for extended therapy is strong in low-to-moderate bleeding risk patients.

Adjuncts

• Thrombolysis (alteplase): massive PE with shock; reduces mortality in haemodynamically compromised patients at a cost of ~2–3% intracranial haemorrhage risk. Not indicated for stable intermediate-risk PE
• IVC filter: reserved for VTE when anticoagulation is contraindicated (PREPIC2 — no benefit when added to anticoagulation); use retrievable filters and remove promptly when safe
• Compression stockings: 30–40 mmHg knee-high for symptom relief (post-thrombotic syndrome prevention benefit debated; SOX Lancet 2014 was negative)
• Early mobilisation: encouraged once anticoagulation is established; does not increase PE risk

D. Australian operations

PBS listings

Per PBS (verified 2026-06-04):

• Apixaban — Authority Required (Streamlined) for VTE treatment and prevention of recurrence
• Rivaroxaban — Authority Required (Streamlined); 15 mg twice daily for treatment phase, 20 mg daily for ongoing, 10 mg daily for extended
• Dabigatran — Authority Required (Streamlined); requires LMWH ≥5 days lead-in for VTE
• Enoxaparin — Authority Required (Streamlined) for VTE treatment; dose-adjusted for weight
• Warfarin — General schedule
• Vitamin K — General schedule
• Idarucizumab (dabigatran reversal), andexanet alfa (FXa reversal) — hospital restricted

MBS items

D-dimer 65129; lower limb venous Doppler 55244; INR 66819; UEC 66500, FBC 65070, LFT 66512; thrombophilia panel 65060 range; antiphospholipid antibodies 65120; CTPA 57350 range (specialist-referred); GPCCMP 965/967 for chronic anticoagulation >6 months; Mental Health Care Plan 2715/2717 for post-PE PTSD or anxiety; practice nurse 10997.

Cancer screening after unprovoked VTE

SOME NEJM 2015 showed that routine CT abdomen/pelvis adds no mortality benefit over targeted history, examination, and age-appropriate cancer screening (cervical, breast, bowel) in unprovoked VTE. Extensive PET-CT-based cancer screening is not recommended. Occult cancer is found in approximately 5–10% of unprovoked VTE in patients over 40 using targeted screening.

Monitoring DOAC patients

DOAC — UEC and LFT at 1 month then 6–12 monthly; annual review of indication, duration, and bleeding risk. Warfarin — INR weekly initially, then 4–6 weekly when stable; target TTR ≥70%. Watch for post-thrombotic syndrome (chronic limb pain, swelling, ulceration — approximately 25–50% after proximal DVT) and chronic thromboembolic pulmonary hypertension (CTEPH; approximately 2–4% post-PE — echocardiogram at 3–6 months if breathlessness persists).

E. Special populations

Pregnancy: LMWH is the only safe anticoagulant during pregnancy (DOACs cross the placenta; warfarin is teratogenic). Enoxaparin 1 mg/kg twice daily or 1.5 mg/kg once daily, with switch to unfractionated heparin peripartum for reversibility. Monitor anti-Xa in pregnancy, extreme weights, and severe renal impairment. Multidisciplinary obstetric and haematology care from diagnosis; shared-care agreement with delivery hospital.

Cancer-associated VTE: Indefinite anticoagulation while cancer or systemic treatment is active. Apixaban is now a reasonable first-line option for most cancer VTE per CARAVAGGIO. Reserve LMWH for active GI or GU cancer with high bleeding risk, or significant thrombocytopenia (platelets <50 × 10⁹/L). Oncology coordination is important as anticoagulation interacts with some chemotherapy protocols.

Older adults: DOACs are generally preferred over warfarin; renal function decline with age requires dose-specific attention (apixaban preferred with CrCl 25–50). Fall risk is a consideration — assess falls risk before deciding on extended anticoagulation; the bleeding risk of a significant fall must be balanced against VTE recurrence risk.

ATSI patients: VTE outcomes are worse in Aboriginal and Torres Strait Islander populations — an under-recognised disparity. Barriers to access, comorbidities, and culturally safe communication about anticoagulation are all relevant. ATSI health assessment (MBS 715) should incorporate VTE prevention counselling.

When to escalate

Refer to the emergency department when:

• Suspected massive PE (haemodynamic compromise, syncope, severe hypoxia)
• Phlegmasia cerulea dolens (extensive iliofemoral DVT with limb-threatening ischaemia)
• Suspected new VTE when imaging is not available within 4 hours in general practice

Refer to haematology or thrombosis clinic semi-urgently for:

• Suspected sub-massive PE, recurrent VTE on anticoagulation, suspected APLS, cancer-associated VTE, pregnancy with VTE

Refer routinely for:

• Thrombophilia screen post-anticoagulation, recurrent unprovoked VTE, post-thrombotic syndrome management, CTEPH workup

What this article is and is not

This is general health information drawn from THANZ 2019 and 2025 guidelines, eTG Cardiovascular, AMH, and the AMPLIFY, EINSTEIN, CARAVAGGIO, TRAPS, YEARS, and SOME trials. It does not constitute personal medical advice and does not create a doctor–patient relationship. Anticoagulant choice, dosing, duration, and monitoring are determined with your treating GP, haematologist, or specialist.

Safety-net: new chest pain, sudden breathlessness, haemoptysis, or syncope → call 000 immediately. New calf or thigh pain and swelling → same-day GP review. Unusual bleeding (blood in urine or stool, prolonged nosebleeds, severe headache) → urgent review.

For Australian consumer resources: HealthDirect — DVT, HealthDirect — PE, Heart Foundation — Pulmonary embolism, Better Health Channel — DVT.

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Sources cited

1. THANZ — VTE diagnosis and management 2019
2. THANZ — 2025 DOAC practical guidance
3. Therapeutic Guidelines (eTG) — Cardiovascular: VTE
4. Australian Medicines Handbook
5. PBS — DOACs and LMWH for VTE
6. Heart Foundation — Pulmonary embolism
7. HealthDirect — DVT
8. HealthDirect — PE
9. Better Health Channel — DVT
10. Agnelli et al. — AMPLIFY: apixaban for VTE (NEJM 2013)
11. EINSTEIN Investigators — rivaroxaban for DVT/PE (NEJM 2010/2012)
12. Agnelli et al. — CARAVAGGIO: apixaban in cancer VTE (NEJM 2020)
13. Pengo et al. — TRAPS: rivaroxaban vs warfarin in APLS (NEJM 2018)
14. van der Hulle et al. — YEARS algorithm (Lancet 2017)