An instrument for surgical insertion and penetration of tissue layers includes a shaft, a distally facing end surface, and at least one cutting feature positioned on the distally-facing end surface. The at least one cutting feature is structurally configured to be atraumatic when not rotated. The at least one cutting feature enables cutting of tissue when the at least one cutting feature is rotated about a rotational axis. The at least one cutting feature can comprise a cutting edge that is positioned tangential relative to an imaginary cylinder centered on the rotational axis and/or a cutting edge that is positioned such that a plane defined along the cutting edge does not extend through the rotational axis.
