A cannula assembly includes a cannula and an obturator. The cannula includes an elongated shaft dimensioned to access tissue. The elongated shaft has a lumen extending therethrough. The elongated shaft includes a first shaft segment having a first pre-determined configuration and a second shaft segment having a second pre-determined configuration different from the first pre-determined configuration. The obturator includes an elongated body adapted for insertion through the lumen of the elongated shaft. The elongated body includes a first body segment having a configuration in general accordance with the first pre-determined configuration of the first shaft segment and a second body segment selectively adaptable to conform to the second pre-determined configuration of the second shaft segment upon insertion through the lumen of the elongated shaft.