01Purpose and principlesWhat the treatment does and how it fits into care.
Endovascular and surgical approaches seek faster reduction of obstructing thrombus than anticoagulation can provide. Catheter-directed thrombolysis places fibrinolytic within clot, potentially reducing total systemic exposure while still carrying intracranial and major bleeding risk. Aspiration, mechanical or pharmacomechanical thrombectomy aims to remove clot with little or no lytic drug, but introduces risks of vascular injury, haemolysis, blood loss, distal embolisation and device-specific complications. Surgical embolectomy provides direct extraction, usually from the pulmonary arteries, at the cost of sternotomy, cardiopulmonary bypass and major operative stress. These are reperfusion tools, not interchangeable labels.
Selection begins with the clinical objective. In high-risk PE the objective is survival through rapid reversal of right-ventricular obstruction. Systemic thrombolysis remains the best-established rapid treatment when permissible. Catheter treatment or surgery becomes important when thrombolysis is contraindicated, has failed, or a specialist team judges another method more suitable. In stable PE with RV strain, routine reperfusion exposes many patients to bleeding without proven clinical benefit; observe and rescue those who deteriorate. In lower-limb DVT the goal differs: relieve severe acute venous obstruction and possibly reduce later morbidity in a narrow group with acute iliofemoral disease. Evidence does not justify routine intervention for less extensive DVT.
Key points
- For PE with shock, assess fibrinolysis eligibility explicitly: use systemic thrombolysis when permitted; if lysis is contraindicated, urgent alternatives are catheter aspiration or mechanical thrombectomy without lytic exposure, or surgical embolectomy—not catheter-directed thrombolysis.
- Do not routinely thrombolyse haemodynamically stable PE, including patients with right-ventricular dysfunction; monitor higher-risk stable patients and prepare rescue escalation.
- For symptomatic iliofemoral DVT, consider catheter-directed thrombolysis only when symptoms have lasted under 14 days, functional status is good, life expectancy is at least 1 year and bleeding risk is low; do not offer thrombus-removal procedures for femoral, popliteal or calf-vein DVT. All intervention choices require multidisciplinary assessment and local capability.
- Catheter-directed thrombolysis infuses fibrinolytic into thrombus; mechanical thrombectomy extracts or fragments clot; pharmacomechanical systems combine both approaches.
- Surgical pulmonary embolectomy opens the pulmonary arteries on cardiopulmonary bypass and is most relevant when rapid mechanical clearance is required and a surgical team is immediately available.
- For acute iliofemoral DVT, early thrombus removal is selective: short symptom duration, severe symptoms, good functional reserve, low bleeding risk and long life expectancy support consideration.
- Routine thrombus removal for femoropopliteal or distal DVT lacks a favourable benefit-risk balance; anticoagulation, mobilisation and symptom care remain central.
- Removing clot does not remove the thrombogenic state: continue or restart anticoagulation when safe and investigate anatomical obstruction when it affects durability.
02Indications, selection and cautionsWho may benefit, who needs urgent treatment and important alternatives.
Shock, persistent hypotension, cardiac arrest or progressive hypoperfusion identifies a time-critical reperfusion problem; anatomical clot size alone is insufficient.
RV dysfunction plus myocardial injury increases concern while blood pressure remains preserved. These patients need close observation, but routine thrombolysis is not supported.
Active or recent critical bleeding, particularly intracranial disease, may prohibit fibrinolysis; persistent shock after lysis raises the need for immediate alternative mechanical reperfusion.
Symptomatic thrombus involving the iliac and common femoral veins may be considered for catheter-directed thrombolysis only when symptoms have lasted under 14 days, functional status is good, life expectancy is at least 1 year and bleeding risk is low.
Massive swelling, cyanosis, severe pain, sensory change or impaired arterial inflow suggests phlegmasia and requires urgent venous and arterial assessment.
03Assessment before treatmentTests and checks that guide safe selection.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Immediate physiology and bleeding assessmentFirst step - Why
- Determine whether urgent reperfusion is needed and which methods remain safe.
- Interpretation and limitations
- Trend blood pressure, perfusion, lactate, oxygenation and neurological state; identify active bleeding, recent surgery and intracranial pathology before exposing the patient to lytic or invasive risk.
- 02
CTPA and right-heart assessment - Why
- Confirm PE anatomy and evaluate right-ventricular pressure overload for procedural planning.
- Interpretation and limitations
- Central clot location may aid access planning, while RV dilatation supports severity assessment; neither clot burden nor RV strain alone mandates intervention in a stable patient.
- 03
Venous duplex and cross-sectional venous imaging - Why
- Define DVT extent, inflow and possible iliocaval obstruction before thrombus removal.
- Interpretation and limitations
- Iliofemoral involvement supports selective consideration; isolated femoropopliteal or distal disease usually favours anticoagulation rather than invasive clearance.
- 04
FBC, coagulation, renal function and group and save - Why
- Identify anaemia, thrombocytopenia, coagulopathy, renal risk and transfusion requirements.
- Interpretation and limitations
- Correct reversible hazards where time permits; results guide contrast planning, anticoagulant handling and readiness for bleeding without delaying life-saving reperfusion.
- 05
Post-procedure angiography or venography - Why
- Confirm flow restoration, residual obstruction and procedure-related injury.
- Interpretation and limitations
- Technical clot reduction is only an intermediate outcome; correlate it with haemodynamic recovery, limb symptoms, bleeding and later patency.
04Treatment approachPreparation, options, escalation and aftercare.
01Emergency PE pathwayReperfusion for haemodynamic collapseFirst stepConfirmed or near-certain PE is causing shock, persistent hypotension or cardiac arrest.+
- 1Provide expert-led resuscitation, continuous monitoring and anticoagulant assessment while activating critical care, interventional radiology or cardiology, and cardiothoracic surgery without serial referral delay.
- 2Decide fibrinolysis eligibility explicitly. Use systemic thrombolysis when indicated and permissible; if lysis is contraindicated or has failed, choose catheter aspiration or mechanical thrombectomy without thrombolytic exposure, or surgical embolectomy, according to anatomy, time and expertise.
- 3Consider catheter-directed thrombolysis or a pharmacomechanical system only after separately confirming that thrombolytic exposure is acceptable; then define the desired clearance speed, access route, device risks and bailout plan.
- 4Confirm restoration of perfusion and RV recovery, detect bleeding or access complications early, and continue therapeutic anticoagulation when safe.
02Rescue pathwayDeteriorating initially stable PEEscalationA monitored normotensive patient develops hypotension, worsening hypoperfusion or escalating respiratory failure.+
- 1AlternativeReassess promptly for PE progression, bleeding, recurrent embolisation and alternative causes of deterioration using bedside physiology and focused imaging.
- 2EscalationEscalate to emergency reperfusion assessment; do not let an earlier low prognostic label delay action after the physiology changes.
- 3Balance systemic lysis against bleeding risk and use catheter or surgical alternatives when the expert team identifies a clear advantage or contraindication.
- 4Record the trigger, selected method, response and subsequent critical-care and anticoagulation plan.
03DVT pathwaySelective iliofemoral thrombus removalAcute severe iliofemoral DVT is present in a suitable patient, or venous obstruction threatens the limb.+
- 1Confirm anatomy and symptom duration, assess functional status, life expectancy, bleeding risk and patient priorities, and begin therapeutic anticoagulation unless contraindicated.
- 2For limb threat, seek immediate venous specialist intervention; otherwise discuss the uncertain long-term benefit and definite bleeding and procedural risks.
- 3Choose catheter-directed, pharmacomechanical or mechanical methods within the service’s governance and evidence boundaries, avoiding routine intervention for distal disease.
- 4Assess residual iliac obstruction, maintain anticoagulation, encourage mobility and monitor for recurrent DVT and post-thrombotic symptoms.
05Complications, monitoring and follow-upAdverse effects, response and longer-term review.
- During PE intervention continuously monitor invasive or frequent blood pressure, rhythm, oxygenation, perfusion, neurological state and lactate, with immediate access to resuscitation and surgical bailout.
- When a thrombolytic is infused, track access sites, haemoglobin, platelet count, coagulation parameters and neurological symptoms; stop and investigate promptly when major bleeding is suspected.
- After mechanical thrombectomy assess haemolysis, renal function, blood loss, vascular injury, distal embolisation and the haemodynamic or limb response rather than reporting device success alone.
- Reassess the anticoagulation start or restart time after haemostasis, because interruption increases recurrent thrombosis while premature treatment can worsen procedural bleeding.
- At follow-up document recurrent VTE, bleeding, functional recovery, venous patency or residual obstruction, post-thrombotic symptoms and persistent dyspnoea.
06Special situationsVariants, exceptions and circumstances that change the usual approach.
Anatomy cannot replace physiology
A saddle embolus can be found in a stable patient, while smaller embolic burden may precipitate shock in limited cardiopulmonary reserve. Intervention decisions begin with haemodynamics and trajectory.
Lower dose is not zero risk
Catheter delivery may reduce total fibrinolytic dose, but intracranial and other major bleeding remain possible. Vascular access, device manipulation and concomitant anticoagulation add separate hazards.
Ultrasound enhancement remains uncertain
NICE finds inadequate evidence that ultrasound enhancement improves efficacy over catheter-directed thrombolysis alone and requires special governance, consent, audit or research arrangements.
DVT goals differ from PE goals
PE reperfusion may be life-saving in shock. DVT thrombus removal usually seeks symptom relief, limb salvage or reduced chronic venous morbidity, so the acceptable evidence and risk threshold differs.
The procedure is one phase
Durable benefit depends on effective anticoagulation, correction of important anatomical outflow obstruction when appropriate, early complication detection and follow-up for recurrent or chronic disease.
07Common pitfallsFrequent interpretation and management errors.
- 01
Treating every central or saddle PE as an indication for thrombectomy ignores haemodynamic state and evidence boundaries.
- 02
Using catheter-directed thrombolysis automatically when systemic thrombolysis is indicated can delay reperfusion without proven outcome benefit.
- 03
Assuming catheter delivery eliminates intracranial bleeding risk produces unsafe consent and surveillance.
- 04
Offering invasive thrombus removal routinely for femoropopliteal or distal DVT overstates benefit and exposes patients to avoidable harm.
- 05
Stopping after technical clot extraction without restoring anticoagulation and planning follow-up invites recurrence and misses chronic sequelae.