AKT · Cardiovascular/Vessels, aorta & venous

Deep vein thrombosis

Venous thrombus in the deep veins (Virchow's triad: stasis, hypercoagulability, endothelial injury)

Overview

Thrombosis of a deep vein, usually the leg, arising from Virchow's triad. The danger is propagation and embolism to the lungs (PE). The two-level Wells score directs whether to image or D-dimer; treatment is anticoagulation, now with a DOAC first-line. Unprovoked or recurrent DVT prompts a search for cancer/thrombophilia.

Recognise

Unilateral leg swelling, pain, warmth, erythema and tenderness along the deep veins; pitting oedema; dilated superficial veins
Risk factors: immobility/surgery, malignancy, pregnancy/oestrogen, prior VTE, thrombophilia, long-haul travel
Phlegmasia (massive swelling with limb compromise) is rare and limb-threatening

Red flags

Symptoms of PE (breathlessness, pleuritic pain, haemoptysis, tachycardia, hypoxia) → investigate/treat for PE
Unprovoked DVT → consider occult cancer and thrombophilia work-up

Differentials & how to tell them apart

Cellulitisinfective, often bilateral risk, raised inflammatory markers, portal of entry

Ruptured Baker's cystsudden calf pain with knee pathology; ultrasound differentiates

Chronic venous insufficiency / lymphoedemachronic, often bilateral, skin changes

Investigations

Two-level DVT Wells score: likely → proximal leg vein ultrasound (D-dimer if delayed); unlikely → D-dimer first (negative excludes, positive → ultrasound). Baseline FBC, U&Es, LFTs, clotting before anticoagulation; investigate cause if unprovoked.

Management

DOAC (apixaban/rivaroxaban) first-line; ≥3 months, extended if unprovoked/cancer

1Apply the two-level DVT Wells score: likely → proximal leg ultrasound; unlikely → D-dimer, then ultrasound only if positive. Start anticoagulation while awaiting confirmation if scan delayed.Gate: Any features of PE → investigate and treat for PE; unprovoked DVT → assess for occult cancer and thrombophilia.
2Anticoagulate with a DOAC (apixaban/rivaroxaban) first-line for at least 3 months; extend for unprovoked, recurrent or cancer-associated VTE after weighing bleeding risk.

DOAC first-line (apixaban or rivaroxaban) — anticoagulant of choice; LMWH bridging only for specific DOAC regimens; LMWH/warfarin if DOAC unsuitable (e.g. antiphospholipid syndrome, severe renal impairment)

Anticoagulation duration: ≥3 months — provoked (transient factor) → 3 months; unprovoked/cancer/recurrent → extended/long-term, weighing bleeding risk

Cancer-associated VTE — a DOAC or LMWH (per tumour site/bleeding risk)

Compression/IVC filter — IVC filter only if anticoagulation contraindicated

Key points

Unilateral hot, swollen, tender calf → two-level Wells: likely = ultrasound, unlikely = D-dimer first. Treat with a DOAC (apixaban/rivaroxaban) for ≥3 months; unprovoked/cancer/recurrent → extended. Unprovoked DVT → look for cancer.

Monitor & prognosis

Renal function for DOAC dosing, recurrence, bleeding; reassess duration at 3 months.

Good with anticoagulation; risks are PE, recurrence and post-thrombotic syndrome.

Source: NICE NG158 (VTE diagnosis & management)