Makindo Medical Notes

IVC filters are mechanical devices placed in the inferior vena cava to trap thrombi from the lower extremities before they reach the pulmonary arteries. ⚠️ Their use should be specialist-led and individualised, as inappropriate placement carries significant long-term risks. Anticoagulation remains the first-line therapy for venous thromboembolism (VTE).

🧾 About

• A small metallic cage-like device deployed percutaneously into the infrarenal IVC.
• Designed to trap emboli arising from DVT, thereby reducing risk of acute pulmonary embolism (PE).
• First developed in the 1960s (Mobin-Uddin), now largely retrievable filters are used.
• IVC filters do not dissolve clot and have no impact on the underlying thrombotic process.

🔍 Accepted Indications

• Absolute contraindication to anticoagulation (e.g. active major bleeding, recent intracranial haemorrhage, neurosurgical procedures).
• Recurrent PE despite therapeutic anticoagulation (rare).
• Complications of anticoagulation such as heparin-induced thrombocytopenia.
• Selected prophylaxis in very high-risk trauma patients (e.g. spinal cord injury, severe polytrauma) if anticoagulation not possible.

❌ Not Recommended / Controversial

• Routine prophylaxis in major surgery without VTE → not recommended.
• Adjunct to anticoagulation in most patients → no survival benefit shown.
• Long-term “just in case” placement → associated with harm.

⚙️ Types

• Permanent filters – rarely used today.
• Retrievable filters – intended for removal once anticoagulation can be safely resumed (ideally within 6–12 weeks).

📊 Evidence & Guidelines

• PREPIC Trial (1998; NEJM 2005 follow-up):
  • Reduced early PE incidence.
  • No improvement in mortality.
  • Increased long-term DVT risk.
• NICE NG158 (2020): Use anticoagulation first line; consider IVC filter only if anticoagulation is contraindicated or fails.
• ESC 2019 PE guidelines: Restrict use to highly selected patients; recommend retrieval within 3 months.
• Cochrane review (2022): Confirms no survival advantage and higher DVT rates with filters.

⚠️ Complications

• Early: Malposition, vessel perforation, bleeding, infection.
• Late: Caval thrombosis, filter migration, fracture, penetration into adjacent structures (duodenum, aorta, vertebrae).
• Long-term DVT risk ↑, especially if filter not retrieved.

🔄 Retrieval

• Plan retrieval at the time of insertion.
• Highest success within 12 weeks; retrieval becomes more technically challenging later.
• Failure to retrieve is common in practice → contributes to avoidable long-term complications.

📌 Clinical Pearls

• Always ask: “Why not anticoagulation?” If anticoagulation is feasible, filter is unnecessary.
• Document indication, duration, and retrieval plan clearly at insertion.
• Always involve interventional radiology and haematology before placement.
• Filters are a rescue option, not a substitute for anticoagulation.

📚 References

• PREPIC Study Group. Eight-Year Follow-Up of Patients With Permanent IVC Filters. NEJM 2005;352:146–53.
• NICE NG158: Venous thromboembolic diseases (2020).
• ESC 2019 Guidelines on Pulmonary Embolism.
• Cochrane Review 2022: Vena caval filters for preventing PE.