Summary

Thrombosis is the formation of a blood clot (thrombus) inside a blood vessel, which can block blood flow and cause serious complications. Think of thrombosis as a blood clot forming where it shouldn't—this can block blood flow, causing ischemia (lack of blood supply) to tissues downstream. There are two main types: venous thrombosis (clot in veins—most commonly deep vein thrombosis DVT in legs, can cause pulmonary embolism PE) and arterial thrombosis (clot in arteries—can cause stroke, heart attack, limb ischemia). Venous thrombosis is more common and usually caused by Virchow's triad (stasis, vessel damage, hypercoagulability). The key to management is recognizing thrombosis (DVT: leg swelling, pain, redness; PE: chest pain, breathlessness, may have hemoptysis), confirming the diagnosis (clinical assessment, D-dimer, imaging—ultrasound for DVT, CT pulmonary angiogram for PE), assessing severity (especially for PE—massive, submassive, or low-risk), and providing appropriate treatment (anticoagulation—usually heparin then warfarin/DOAC, thrombolysis if massive PE, compression stockings for DVT). Early recognition and prompt treatment are essential—delayed treatment increases the risk of complications (PE from DVT, death from massive PE).

Key Facts

• Definition: Formation of blood clot inside blood vessel
• Incidence: Common (thousands of cases/year)
• Mortality: Low for DVT (<1%), higher for PE (5-10% if not treated)
• Peak age: All ages, but more common in older adults
• Critical feature: Blood clot blocking vessel, signs of ischemia/embolism
• Key investigation: Clinical assessment, D-dimer, imaging (ultrasound for DVT, CTPA for PE)
• First-line treatment: Anticoagulation (heparin then warfarin/DOAC)

Clinical Pearls

"DVT + breathlessness = PE until proven otherwise" — If a patient with DVT develops breathlessness or chest pain, think pulmonary embolism. Don't miss this—PE can be fatal.

"Wells score helps but don't rely on it alone" — The Wells score helps assess probability of DVT/PE, but clinical judgment is still important. If high suspicion, treat even if score low.

"D-dimer is sensitive but not specific" — D-dimer is very sensitive (rules out if negative in low probability), but not specific (many things cause positive). Use with clinical probability.

"Anticoagulate early" — Once thrombosis is diagnosed, start anticoagulation immediately (usually heparin). Don't delay—this prevents complications.

Why This Matters Clinically

Thrombosis is common and can cause serious complications (PE from DVT, death from massive PE, stroke from arterial thrombosis). Early recognition (especially DVT and PE), prompt diagnosis, and immediate anticoagulation are essential. This is a condition that emergency clinicians, haematologists, and other specialists manage, and prompt treatment prevents complications and saves lives.

Structured Approach: ABCDE

A - Airway

• Assessment: Usually patent
• Action: Secure if compromised

B - Breathing

• Look: May have respiratory distress (if PE)
• Listen: May have crackles, pleural rub (if PE)
• Measure: SpO2 (may be low if PE), respiratory rate (may be high)
• Action: Support if needed, oxygen

C - Circulation

• Look: May have signs of shock (if massive PE)
• Feel: Pulse (may be fast, weak), BP (may be low)
• Listen: Heart sounds (may have signs of right heart strain if PE)
• Measure: BP (may be low), HR (may be fast)
• Action: Resuscitate if shock

D - Disability

• Assessment: Usually normal (may be altered if massive PE, stroke)
• Action: Assess if severe

E - Exposure

• Look: Full examination, leg examination (DVT), chest (PE)
• Feel: Leg (swelling, tenderness), assess for DVT
• Action: Complete examination

Specific Examination Findings

DVT Examination:

• Inspection:
  • Swelling: Compare legs, measure if needed
  • Redness: Check for redness
  • Veins: May have visible veins
• Palpation:
  • Tenderness: Painful
  • Warmth: Warm to touch
  • Calf: Check calf for tenderness

PE Examination:

• Respiratory:
  • Rate: Fast
  • SpO2: May be low
  • Chest: May have crackles, pleural rub
• Cardiovascular:
  • HR: Fast
  • BP: May be low (if massive)
  • JVP: May be elevated (if right heart strain)

Special Tests

Natural History (Without Treatment)

Untreated Thrombosis:

• PE from DVT: High risk (20-30%)
• Death from PE: High risk (5-10%)
• Poor outcomes: If not treated

Outcomes with Treatment

Factors Affecting Outcomes:

Good Prognosis:

• Early treatment: Better outcomes
• No complications: Better outcomes
• Good compliance: Better outcomes
• Appropriate duration: Better outcomes

Poor Prognosis:

• Delayed treatment: Higher risk of PE
• Massive PE: Higher mortality
• Recurrent: Worse outcomes
• Poor compliance: Worse outcomes

Prognostic Factors

Key Guidelines

1. NICE Guidelines (2020) — Venous thromboembolic diseases: diagnosis, management and thrombophilia testing. National Institute for Health and Care Excellence

Key Recommendations:

• Anticoagulation for DVT/PE
• Thrombolysis for massive PE
• Evidence Level: 1A

Landmark Trials

Multiple studies on anticoagulation, thrombolysis, outcomes.

Evidence Strength

What is Thrombosis?

Thrombosis is when a blood clot forms inside a blood vessel, blocking blood flow. Think of it as a blood clot forming where it shouldn't—this can block blood flow, causing problems. There are two main types: deep vein thrombosis (DVT—clot in a leg vein) and pulmonary embolism (PE—clot in a lung artery, often from a DVT that breaks off).

In simple terms: You have a blood clot in a blood vessel. This is serious because it can block blood flow and cause complications (like a clot traveling to your lung), but with proper treatment, most people do well.

Why does it matter?

Thrombosis can cause serious complications (PE from DVT can be fatal, arterial thrombosis can cause stroke or heart attack). Early recognition and prompt anticoagulation are essential. The good news? With proper treatment, most people do well.

Think of it like this: It's like a blood clot blocking a pipe—it needs to be treated to prevent complications, but once treated, most people do well.

How is it treated?

1. Diagnosis:

• Assessment: Your doctor will assess you and may do tests (ultrasound for DVT, CT scan for PE)
• Why: To confirm the diagnosis and see how serious it is

2. Anticoagulation (Urgent):

• What: You'll get medicines to thin your blood (anticoagulants) to prevent the clot from getting bigger and prevent new clots
• When: Usually starts immediately
• Why: To treat the clot and prevent complications (like a clot traveling to your lung)
• Duration: Usually 3-6 months (longer if you've had clots before or are at high risk)

3. Supportive Care:

• If DVT: You'll wear compression stockings to help your leg
• If PE: You'll get oxygen if needed
• Mobilization: Once you're on anticoagulation, you can usually move around (this actually helps)

4. Thrombolysis (If Massive PE):

• What: If you have a very large clot in your lung causing shock, you may get a medicine to dissolve the clot (thrombolysis)
• When: Only if very severe
• Why: To quickly dissolve the clot and save your life

The goal: Treat the clot (anticoagulation), prevent complications (especially PE from DVT), and help you recover.

What to expect

Recovery:

• Treatment: Usually starts immediately
• Hospital stay: Usually days (PE) or may be outpatient (DVT if stable)
• Full recovery: Most people recover well with treatment

After Treatment:

• Medicines: You'll need to take anticoagulants for several months (usually 3-6 months, longer if needed)
• Monitoring: Your doctor will monitor your blood to make sure the medicine is working (if warfarin)
• Lifestyle: Usually can live normally, but need to be careful about bleeding (avoid injuries, etc.)
• Follow-up: Regular follow-up to monitor your treatment

Recovery Time:

• Acute phase: Usually days to weeks
• Long-term: Ongoing anticoagulation for months

When to seek help

Call 999 (or your emergency number) immediately if:

• You have chest pain and difficulty breathing (possible PE)
• You have a leg that's very swollen and painful (possible DVT)
• You're coughing up blood
• You feel very unwell
• You have symptoms that concern you

See your doctor if:

• You have leg swelling or pain that concerns you
• You have chest pain or difficulty breathing
• You have a known thrombosis and develop new symptoms
• You have concerns about your treatment

Remember: If you have chest pain and difficulty breathing, especially if you also have leg swelling, call 999 immediately—this may be a pulmonary embolism, which can be fatal. Thrombosis is serious, but with prompt treatment, most people do well. Don't delay—if you're worried, seek help immediately.