An obturator for penetrating tissue includes an outer member defining a longitudinalaxis, and having proximal and distal ends, a leading member disposed adjacentthe distal end of the outer member and having a tissue contacting outer surface,and a blade mounted adjacent to the leading member. The blade is adapted for atleast traversing movement relative to the longitudinal axis to thereby traversethe outer surface of the leading member to facilitate penetrating of tissue duringadvancement of the leading member within the tissue. The leading member may includean optical window adapted to permit passage of light therethrough for detectionby a clinician.
