What is used to maintain the shape of a catheter during insertion?

The correct answer, the stylet, is specifically designed to provide rigidity and shape to a catheter during its insertion. It is a solid, narrow rod that fits inside the catheter, allowing the clinician to maintain control and directionality while navigating through the vascular system or other anatomical pathways. The stylet helps to establish the desired curvature or form of the catheter, making it easier to maneuver through difficult bends or other anatomical challenges.

While guide wires are also utilized in catheterization procedures, they serve a different purpose by creating a pathway for the catheter to follow rather than maintaining the shape during insertion. Sheaths and balloons can have their own roles in the overall procedure, but they do not contribute to forming the structure of the catheter itself during the insertion phase. The focus of the question is specifically on the mechanism used to facilitate the insertion process, which is effectively fulfilled by the stylet.