bougie

(medicine) A tapered cylindrical instrument for introducing an object into a tubular anatomical structure, or to dilate such a structure, as with an esophageal bougie.

Example: 2001, Oliver Sacks, Uncle Tungsten: Memories of a Chemical Boyhood, Alfred A. Knopf (2001), 12, I was not too sure, as a child, what doctors "did," and glimpses of catheters and bougies in their kidney dishes, retractors and speculums, rubber gloves, catgut thread, and forecepts - all this, I think, rather frightened me, though it fascinated me too.