In percutaneous transluminal angioplasty (PTA), the Seldinger technique involves initial puncture of the artery with a needle, followed by insertion of a guidewire through the needle. What is the next step?

• A Inject contrast directly through the needle to confirm arterial position
• B Insert the balloon catheter directly through the needle
• C Withdraw the needle over the guidewire, then advance a sheath/dilator over the wire ✓
• D Remove the guidewire, insert the catheter through the needle hub

Explanation

The Seldinger technique (1953) is the universal technique for percutaneous vascular access: (1) Puncture artery with hollow needle; (2) Pass guidewire through needle lumen into vessel; (3) Withdraw needle over guidewire while maintaining wire position; (4) Pass dilator/introducer sheath over wire; (5) Remove dilator, wire now exits through sheath sideport; (6) Exchange over wire for desired catheter/device. The key principle is that the wire remains in the vessel as all exchanges happen over it. Injecting contrast through a narrow-bore access needle risks arterial haematoma. All modern vascular interventions (PTA, TACE, TIPS, stent placement) use this foundational technique.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.