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Basics of interventional radiology

Interventional radiology performs percutaneous procedures under imaging guidance — vascular access, drainage, biopsy, embolisation, ablation and devices — and each procedure has a defined bleeding risk, typical complications and a safe puncture site.

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Why it matters in the exam

Arterial access: the common femoral artery, over the femoral head; a high puncture (above the inguinal ligament) risks retroperitoneal haematoma, and a low one — pseudoaneurysm and arteriovenous fistula. Radial access — fewer bleeding complications. The commonest complication — haematoma; a pseudoaneurysm (lacking all three wall layers) is treated by US-guided thrombin injection; an arteriovenous fistula presents with a thrill and bruit. CO2 as a contrast agent suits renal failure and iodine allergy, but is forbidden in arteries above the diaphragm (brain and heart). Bleeding risk (SIR 2019): low-risk procedures — thoracentesis and paracentesis, superficial biopsy; high-risk — liver or kidney biopsy, nephrostomy, biliary drainage, TIPS and ablation. In high risk, INR above 1.5–1.8 and platelets below 50,000 are corrected.

Drainage: an accessible abscess above 3 cm is drained under CT or US guidance. Nephrostomy: puncture of a posterior calyx, usually in the lower pole, through the relatively avascular zone (Brödel), to avoid large arteries; the commonest significant complication — bleeding; nephrostomy in a non-dilated kidney is more difficult. Right percutaneous biliary drainage — in the mid-axillary line, below the 10th intercostal space so as not to cross the pleura. Transhepatic percutaneous cholecystostomy reduces bile leak. Ablation: RF and microwave kill by heat, and nearby vessels "cool" the zone (heat sink); cryoablation kills by ice and the ice ball is seen on CT. TACE for HCC — contraindications: advanced liver failure, biliary obstruction and complete thrombosis of the main portal vein.

Aortic aneurysm after EVAR — endoleaks: I — at the attachment site, treated urgently; II — retrograde flow from lumbar arteries or the IMA, the commonest, followed up unless the aneurysm grows; III — between graft components or through a hole, treated; IV — through the graft wall, self-limiting; V — sac pressure without a visible leak (endotension). IVC filter: indication — venous thrombosis with a contraindication to anticoagulation; infrarenal position, tip at the level of the renal veins, and retrieval when possible. Dialysis access: an arteriovenous fistula is the best route; a tunnelled catheter is best in the right internal jugular vein, with its tip in the right atrium. Temporary embolisation — gelfoam; permanent — coils, plugs, particles and glue.

Key points

• Femoral access over the femoral head.
• Pseudoaneurysm — US-guided thrombin.
• High risk: liver, kidney, nephrostomy, biliary.
• Endoleak II commonest, I and III for treatment.
• Arteriovenous fistula — the best dialysis access.

Summary table

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Sources

• SIR Consensus Guidelines for the Periprocedural Management of Thrombotic and Bleeding Risk, 2019 — Low- and high-risk procedures; INR and platelet thresholds
• ESVS Clinical Practice Guidelines on the Management of Abdominal Aorto-iliac Artery Aneurysms, 2024 — Endoleak classification and follow-up
• CIRSE Standards of Practice on Inferior Vena Cava Filters, 2021 — Indications and placement

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.