A surgical system for penetrating tissue includes an obturator having an obturator housing and an obturator member extending from the obturator housing and having a penetrating member adapted to penetrate tissue. The penetrating member defines an outer wall with an irregular surface dimensioned to facilitate passage through tissue. The obturator may further include a stylet at least partially disposed within the obturator member. The stylet and the obturator member are adapted for relative longitudinal movement between a first relative position corresponding to an unarmed condition of the penetrating member and a second relative position corresponding to an armed condition of the penetrating member.