An open ended tubular sheath is provided with an annular guide element to facilitate placement of the sheath within a body passage. In use a guide wire is directed into the passage and the guide element is then slid over the wire to direct the sheath into the passage. Once in place, the sheath may be used to direct instruments into the passage without significant abrasion or trauma. The guide element may take the form of a loop or tube. Column strength may be provided to the sheath either by the guide element or a stiffener engaged with the element or the sheath.