The insertion of a sterile guidewire through an existing vascular catheter that needs to be replaced. The catheter can then be removed over the guidewire and the new sterile catheter can be inserted over the guidewire, causing less tissue and vascular trauma. This cannot be done if the original catheter is implicated in a tissue or bloodstream infection. Guidewire exchanges must be performed under maximum sterile precautions with a full body drape coverage, as in the initial insertion.