A loading dilator (20) for positioning a medical apparatus (80) across an opening (94) formed through a body wall of a patient includes a tubular body having a relatively rigid proximal portion and a distal portion, the distal portion including a first relatively flexible segment (32) and a second relatively rigid segment (34). The first segment is axially extendable from a first length that has a greater diameter than the second segment, to a second length having a diameter that does not substantially exceed the diameter of the second segment. A stylet (50) is movable in a passageway of the tubular body between a first position wherein the first segment has the first length, and a second position wherein the stylet distal end exerts an axially displacing force on the second segment such that the first segment is movable from the first length to the second length.
