A surgical apparatus for penetrating tissue includes an outer member defining a longitudinal axis and having an outer peripheral wall and an inner member at least partially disposed within the outer member. The inner member includes a penetrating member adjacent the distal end of the outer member. The penetrating member has a substantially annular peripheral edge adapted to penetrate tissue. The inner member and the outer member are adapted for relative longitudinal movement between first and second longitudinal positions. In the first position, the annular peripheral edge of the penetrating member is substantially confined within the outer peripheral wall of the outer member and wherein, in the second position, the annular peripheral edge is at least partially exposed from the outer peripheral wall to facilitate penetration through tissue.
