50. Thrombophlebitis, phlebothrombosis and post-phlebitic syndrome

1. Definition

• Superficial thrombophlebitis (superficial vein thrombosis, SVT) → thrombus with inflammation in a superficial vein
• Phlebothrombosis (deep vein thrombosis, DVT) → thrombus in a deep vein, often with little inflammation; can break off → pulmonary embolism (PE)
• Venous thromboembolism (VTE) → DVT and PE together
• Post-phlebitic (post-thrombotic) syndrome (PTS) → chronic venous insufficiency after DVT: pain, swelling, skin changes, ulcers

2. Epidemiology

• VTE → about 1–2 per 1,000 people a year; rises sharply with age
• Without prophylaxis → DVT after major general surgery in 20–30%, after hip or knee replacement in 40–60%
• PE → a leading cause of preventable death in hospital
• SVT → about 25% have a DVT at diagnosis
• PTS → 20–50% after DVT; severe in 5–10%

3. Aetiology and risk factors

Virchow's triad

1. Stasis → immobility, surgery, long travel, paralysis, heart failure, pregnancy, varicose veins
2. Hypercoagulability:
   • Acquired → cancer, surgery, trauma, oestrogen (pill, HRT), pregnancy, sepsis, nephrotic syndrome, antiphospholipid syndrome, polycythaemia
   • Inherited → factor V Leiden (most common), prothrombin gene mutation, protein C, protein S and antithrombin deficiency
3. Vein wall injury → trauma, surgery, central lines, previous DVT

Superficial thrombophlebitis

• Varicose veins (most common in the leg)
• IV cannula, infusions, drug injection (arm)
• Pregnancy, pill, cancer
• Migratory (thrombophlebitis migrans) → Trousseau's sign of cancer (pancreas, lung), Buerger's disease, Behçet's

4. Pathogenesis

DVT

1. Starts at the valve cusps of calf veins (stasis, low oxygen)
2. Platelets and fibrin build up → red thrombus
3. Grows upwards → popliteal, femoral, iliac veins
4. Free-floating tail → breaks off → PE
5. Thrombus organises; vein recanalises over months, but valves are destroyed

Post-thrombotic syndrome

1. Destroyed valves → reflux; residual clot → obstruction
2. Venous hypertension when standing and walking (failed calf pump)
3. Capillary leak → oedema, haemosiderin, fibrosis
4. Skin breaks down → venous ulcer

5. Classification

By site

• Distal (calf) DVT → below the popliteal vein; lower PE risk
• Proximal DVT → popliteal and above; higher PE risk
• Iliofemoral → worst swelling and highest PTS risk
• Upper limb → catheters, Paget-Schroetter syndrome (effort thrombosis of the subclavian vein, thoracic outlet)

By cause

• Provoked → major transient risk (surgery, trauma, immobility)
• Unprovoked → no clear cause; higher recurrence; look for cancer

Severe forms

• Phlegmasia alba dolens → white, swollen, painful leg (iliofemoral DVT)
• Phlegmasia caerulea dolens → blue, very swollen leg; arterial flow blocked → venous gangrene

PTS: Villalta score

• 5 symptoms (pain, cramps, heaviness, itching, paraesthesia) + 6 signs (oedema, skin induration, pigmentation, redness, venous ectasia, calf pain on compression), each 0–3
• Ulcer → severe PTS
• 5–9 mild, 10–14 moderate, ≥ 15 or ulcer → severe

6. Clinical picture

Symptoms

• SVT → painful, red, hot, tender cord along a superficial vein
• DVT:
  • Often no symptoms
  • Calf pain, swelling of the leg
  • Warmth, redness
  • Mild fever
  • PE → sudden dyspnoea, pleuritic pain, haemoptysis, collapse
• PTS → heavy, aching, swollen leg, worse at the end of the day; itching; ulcers

Signs

• SVT → palpable tender cord, redness along the vein; check that it is not near the SFJ
• DVT:
  • Unilateral pitting oedema
  • Calf swelling > 3 cm compared with the other leg (10 cm below the tibial tuberosity)
  • Tenderness along the deep veins
  • Distended superficial veins
  • Homans' sign (calf pain on dorsiflexion) → unreliable; not used
• Phlegmasia caerulea dolens → massive swelling, blue, cold, no pulses
• PTS → oedema, pigmentation, eczema, lipodermatosclerosis, medial gaiter ulcer

7. Diagnosis

DVT pathway

1. Two-level Wells score for DVT:
   • Active cancer, paralysis or plaster, bedridden > 3 days or surgery < 12 weeks, tenderness along deep veins, whole leg swollen, calf > 3 cm bigger, pitting oedema, collateral veins, previous DVT → +1 each
   • Alternative diagnosis as likely → −2
   • ≥ 2 → DVT likely; ≤ 1 → DVT unlikely
2. DVT likely → proximal leg duplex ultrasound within 4 h
3. DVT unlikely → D-dimer; negative → DVT excluded; positive → duplex
4. Duplex ultrasound → test of choice; vein does not compress, no flow
5. Venography → rarely
6. D-dimer → sensitive, not specific (raised after surgery, cancer, infection, pregnancy, age)
7. CT pulmonary angiography → suspected PE

Other tests

• FBC, clotting, U&E, liver tests (before anticoagulation)
• Unprovoked DVT → history and examination for cancer; thrombophilia testing only in selected patients
• SVT → duplex to look for DVT and distance from the SFJ

8. Differential diagnosis

• Ruptured Baker's (popliteal) cyst
• Cellulitis
• Calf muscle tear or haematoma
• Lymphoedema
• Heart failure, hypoalbuminaemia (both legs)
• Compartment syndrome
• Superficial thrombophlebitis

9. Treatment

Conservative: prevention

• Risk assessment for all admissions
• Mechanical → early mobilisation, hydration, graduated stockings, intermittent pneumatic compression
• Drugs → low molecular weight heparin (LMWH), fondaparinux, DOACs after joint replacement
• Extended prophylaxis (28 days) → major abdominal or pelvic cancer surgery, hip replacement

Conservative: superficial thrombophlebitis

• Analgesia, NSAIDs, warm compresses, compression, keep walking
• ≥ 5 cm long, or near the SFJ → fondaparinux 2.5 mg daily for 45 days (or prophylactic LMWH, rivaroxaban 10 mg)
• Within 3 cm of the SFJ → treat as a DVT (full anticoagulation)
• Cannula-related → remove the cannula
• Later → treat the varicose veins

Conservative: DVT

• Anticoagulation:
  • DOAC → apixaban or rivaroxaban first-line (no injections, no monitoring)
  • LMWH → in pregnancy (warfarin and DOACs not used) and in some patients with cancer
  • Warfarin → INR 2–3, started with LMWH for at least 5 days until INR ≥ 2 for 24 h
  • Unfractionated heparin → kidney failure, high bleeding risk, before procedures (APTT 1.5–2.5 × normal)
• Duration:
  • Provoked → 3 months
  • Unprovoked → 3–6 months, then consider long-term
  • Cancer → at least 6 months
• Calf DVT → anticoagulate, or repeat scan at 1 week
• Elevation, early walking
• Heparin-induced thrombocytopenia (HIT) → platelet fall day 5–14; stop heparin, use argatroban or fondaparinux

Surgical: DVT

• Catheter-directed thrombolysis or pharmacomechanical thrombectomy → selected iliofemoral DVT in young, fit patients with recent symptoms (< 14 days) and low bleeding risk
• Phlegmasia caerulea dolens → urgent thrombolysis or surgical venous thrombectomy (Fogarty catheter) ± fasciotomy
• Inferior vena cava (IVC) filter → only when anticoagulation is contraindicated or PE recurs despite it; remove when possible
• May-Thurner syndrome → venous stent of the left common iliac vein
• Venous bypass (Palma operation: crossover saphenous vein graft for iliac occlusion), valve repair → rarely

Conservative: post-thrombotic syndrome

• Compression → class II–III stockings for life; bandaging for ulcers
• Elevation, exercise, weight loss, skin care (emollients, treat eczema)
• Ulcer → four-layer compression bandaging, dressings, skin graft
• Treat superficial reflux (ablation)
• Iliac vein stenting → deep vein obstruction
• Deep valve repair or transposition → specialist centres only

10. Complications

• Pulmonary embolism → death, chronic thromboembolic pulmonary hypertension
• Post-thrombotic syndrome, venous ulcer
• Recurrent DVT
• Venous gangrene
• Paradoxical embolism → stroke (patent foramen ovale)
• Anticoagulation → bleeding, HIT, osteoporosis (long-term heparin)
• SVT → spreads into deep veins (DVT or PE)