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Deep Vein Thrombosis (DVT) ✅

🦵 Initial Deep Vein Thrombosis (DVT) Assessment & Management

🧠 Key NICE principle: Do not diagnose DVT clinically. Use the two-level Wells score to estimate probability, then combine D-dimer and proximal leg vein ultrasound. If imaging is delayed, start interim therapeutic anticoagulation unless contraindicated.

📝 NICE NG158 Initial DVT Pathway — Two-Level Wells Score

1️⃣ Wells Score Criteria

Add +1 point for each of the following:

Active cancer: treatment ongoing, within 6 months, or palliative
Paralysis, paresis, or recent plaster immobilisation of the lower limb
Recently bedridden for ≥3 days or major surgery within 12 weeks requiring general or regional anaesthesia
Localised tenderness along the distribution of the deep venous system
Entire leg swollen
Calf swelling ≥3 cm compared with the asymptomatic leg, measured 10 cm below the tibial tuberosity
Pitting oedema confined to the symptomatic leg
Collateral superficial veins, non-varicose
Previously documented DVT

Subtract 2 points:

Alternative diagnosis is at least as likely as DVT

2️⃣ NICE Interpretation

✅ ≤1 point: DVT unlikely
🚨 ≥2 points: DVT likely

3️⃣ Diagnostic Pathway

Clinical probability	Next step	Result and action
Wells ≤1 DVT unlikely	Perform D-dimer, ideally with result available within 4 hours.	D-dimer negative: DVT excluded; consider alternative diagnosis. D-dimer positive: arrange proximal leg vein ultrasound, ideally within 4 hours. If ultrasound delayed beyond 4 hours: give interim therapeutic anticoagulation and arrange ultrasound within 24 hours.
Wells ≥2 DVT likely	Arrange proximal leg vein ultrasound, ideally with result available within 4 hours.	Ultrasound positive: diagnose DVT and treat. Ultrasound negative: perform D-dimer. Ultrasound negative + D-dimer negative: DVT unlikely; stop interim anticoagulation and consider alternative diagnosis. Ultrasound negative + D-dimer positive: stop interim anticoagulation and repeat proximal leg ultrasound in 6–8 days. If ultrasound delayed beyond 4 hours: take D-dimer, start interim therapeutic anticoagulation and arrange ultrasound within 24 hours.

4️⃣ If DVT Confirmed

💊 First-line: offer apixaban or rivaroxaban for most patients with confirmed proximal DVT.
If apixaban or rivaroxaban unsuitable: consider LMWH for at least 5 days followed by dabigatran or edoxaban, or LMWH with a vitamin K antagonist such as warfarin.
Active cancer-associated thrombosis: consider DOAC or LMWH depending on tumour site, bleeding risk, renal function, drug interactions and specialist advice.
Triple-positive antiphospholipid syndrome: avoid DOACs; specialist advice is needed, and warfarin is usually preferred.
Pregnancy: use LMWH; avoid DOACs and warfarin during pregnancy.

5️⃣ Duration of Anticoagulation

📆 Provoked proximal DVT / PE e.g. surgery, trauma, immobility → usually 3 months, then consider stopping if the provoking factor has resolved and the clinical course is uncomplicated.
📆 Unprovoked DVT / PE → treat for at least 3 months, then reassess recurrence risk, bleeding risk and patient preference. Consider extended anticoagulation if recurrence risk outweighs bleeding risk.
📆 Active cancer-associated thrombosis → treat for 3–6 months, then reassess; many patients continue while cancer is active or treatment is ongoing.
♾️ Recurrent VTE → consider long-term / indefinite anticoagulation, especially if unprovoked or due to persistent risk factors, provided bleeding risk is acceptable.

🧠 About Deep Vein Thrombosis

DVT is thrombosis within the deep venous system, most often affecting the calf, popliteal or femoral veins.
Most clinically significant pulmonary emboli arise from proximal leg or pelvic DVT.
Untreated DVT may cause pulmonary embolism 🫁 or post-thrombotic syndrome.
Post-thrombotic syndrome causes chronic pain, swelling, heaviness, skin pigmentation and venous ulceration due to venous valve damage and chronic venous hypertension.
Pathophysiology follows Virchow’s Triad:

🩸 Hypercoagulability — cancer, pregnancy, thrombophilia, oestrogen therapy
🛌 Venous stasis — immobility, surgery, long travel, heart failure
🧱 Endothelial injury — trauma, surgery, central venous access

⚠️ Risk Factors

🛌 Immobility, acute illness, stroke or neurological disease
🔪 Recent surgery, especially orthopaedic, pelvic or major abdominal surgery
🎗️ Active malignancy
🤰 Pregnancy and postpartum period
💊 Combined hormonal contraception or HRT
🧬 Inherited or acquired thrombophilia
👵 Age >60
⚖️ Obesity
🚬 Smoking
✈️ Long-distance travel, especially >4 hours
❤️ Heart failure
🦠 Previous VTE

💊 Combined Hormonal Contraception & VTE Risk

Combined hormonal contraception increases VTE risk, but the absolute risk in young healthy women remains low.
Risk varies with oestrogen dose, progestogen type, age, smoking, obesity, thrombophilia and personal/family VTE history.
Pregnancy and the postpartum period carry a higher VTE risk than combined hormonal contraception.

🩺 Clinical Presentation

Unilateral calf or leg swelling
Calf pain, heaviness or tenderness
Warmth and erythema
Dilated superficial collateral veins
Pitting oedema of the affected limb
Calf circumference increase >3 cm compared with the other leg

⚠️ Classical signs such as Homan’s sign have poor sensitivity and specificity and are not recommended for diagnosing DVT.

🔍 Investigations

🧮 Two-level Wells score: first step in suspected DVT.
🧪 D-dimer: useful to help exclude DVT in the NICE pathway; a positive result does not diagnose DVT.
🩻 Proximal leg vein compression ultrasound: first-line imaging test.
🧲 MRI/CT venography: selected cases, such as suspected pelvic or iliac vein thrombosis.
🧬 Thrombophilia testing: only in selected patients and usually not during the acute event.
🧫 Baseline bloods before anticoagulation: FBC, U&Es/eGFR, LFTs and clotting screen where appropriate.

⚠️ Complications

🫁 Pulmonary embolism
🦵 Post-thrombotic syndrome
🔁 Recurrent venous thromboembolism
🩸 Bleeding complications from anticoagulation

🔄 Differential Diagnoses

Calf haematoma
Ruptured Baker’s cyst
Cellulitis, Lymphoedema
Chronic venous insufficiency
Superficial thrombophlebitis
Gastrocnemius or soleus muscle tear
Acute limb ischaemia, if pain is severe with pallor, pulselessness or neurological deficit

💊 Management Overview

Many stable patients can be managed via an ambulatory DVT pathway. Start anticoagulation promptly once DVT is confirmed, or give interim anticoagulation if imaging is delayed and bleeding risk is acceptable. Encourage mobilisation and hydration once anticoagulation has been started.
Do not routinely use graduated compression stockings to prevent post-thrombotic syndrome or recurrent VTE. Compression may be considered for symptom relief in selected patients, following local guidance.

💊 DOAC Doses for Treatment of DVT / PE

DOAC	Initial treatment dose	Ongoing treatment dose	Extended prevention dose	Key notes
Apixaban	10 mg PO twice daily for 7 days	5 mg PO twice daily	2.5 mg PO twice daily after completing 6 months of treatment, if extended prevention is indicated	No initial LMWH required. Often preferred in practice due to lower GI bleeding risk compared with some alternatives.
Rivaroxaban	15 mg PO twice daily for 21 days	20 mg PO once daily	10 mg PO once daily after at least 6 months of treatment, if extended prevention is indicated	No initial LMWH required. Take 15 mg and 20 mg doses with food.
Dabigatran	LMWH / UFH for at least 5 days first	150 mg PO twice daily	Usually 150 mg PO twice daily if continuing; specialist advice for dose adjustment	Requires initial parenteral anticoagulation. Avoid if CrCl <30 mL/min. Dyspepsia is common.
Edoxaban	LMWH / UFH for at least 5 days first	60 mg PO once daily	Usually 60 mg PO once daily if continuing; reduce dose in selected patients	Requires initial parenteral anticoagulation. Reduce to 30 mg once daily if CrCl 15–50 mL/min, body weight ≤60 kg, or interacting P-gp inhibitors.

🧠 Simple memory rule:
Apixaban and rivaroxaban can be started immediately for acute DVT/PE.
Dabigatran and edoxaban need at least 5 days of LMWH/UFH first.

🎓 Exam Tips – Deep Vein Thrombosis

Two-level Wells score is used in NICE guidance: ≤1 = DVT unlikely; ≥2 = DVT likely.
D-dimer does not diagnose DVT. It helps exclude DVT when used correctly in the NICE pathway.
Positive D-dimer is non-specific and may occur with infection, inflammation, malignancy, surgery, trauma, pregnancy and older age.
Proximal leg vein ultrasound is first-line imaging for suspected DVT.
If ultrasound is delayed beyond 4 hours, NICE recommends interim therapeutic anticoagulation and ultrasound within 24 hours, unless anticoagulation is contraindicated.
Apixaban or rivaroxaban are first-line for most patients with confirmed proximal DVT.
Pregnancy: use LMWH; avoid DOACs and warfarin.
Provoked DVT usually needs anticoagulation for 3 months.
Unprovoked DVT needs at least 3 months, then reassess recurrence risk, bleeding risk and patient preference.
Unprovoked VTE and cancer: perform history, examination and baseline blood tests; investigate further only if symptoms or signs suggest malignancy.
Homan’s sign is unreliable and should not be used to diagnose DVT.

📚 References

NICE NG158: Venous thromboembolic diseases — diagnosis, management and thrombophilia testing.
Wells PS, Anderson DR, Bormanis J, et al. Value of assessment of pretest probability of deep-vein thrombosis in clinical management. The Lancet. 1997;350(9094):1795–1798.
Konstantinides SV, Meyer G, Becattini C, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism. European Heart Journal. 2020;41(4):543–603.
Kearon C, Akl EA, Ornelas J, et al. Antithrombotic Therapy for VTE Disease: CHEST Guideline and Expert Panel Report. Chest. 2016;149(2):315–352.

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