Which of the following is NOT one of the steps in the Seldinger Technique?

The Seldinger Technique is a widely used method for gaining vascular access, which involves several critical steps aimed at safely placing a catheter into a blood vessel. The procedure typically includes the insertion of a needle to access the vessel, the threading of a guidewire through the needle, the removal of the needle while leaving the guidewire in place, and finally, the threading of the catheter over the guidewire into the vessel.

The step identified as 'injection of contrast' does not belong to the core sequence of the Seldinger Technique. While contrast injection is a common procedure that occurs during many interventional radiology tasks, including imaging studies after catheter placement, it does not directly relate to the steps necessary to perform the Seldinger Technique itself. This technique focuses specifically on achieving vascular access and preparing for catheter placement, rather than the imaging or injection processes that may follow.

In the context of the other steps, they are integral to successfully and safely establishing access to the vascular system, whereas contrast injection is an ancillary procedure typically performed later in the workflow. Thus, recognizing the distinct purpose and timing of these actions within the broader framework of interventional procedures clarifies why injection of contrast is not part of the Seldinger Technique.