Abstract: A cannula includes a coupling interface adapted to receive and engage a wide variety of medical instruments having engaging portions which are different. In general, the cannula includes an elongated insertion member having a passage for receiving the medical instrument and a clamping assembly disposed at the proximal end of the elongated insertion member to engage the medical instrument. The clamping assembly includes a second surface axially spaced from the first surface of the elongated insertion member, and a biasing member positioned to bias at least one of the first surface and the second surface axially toward each other and to clamp an engaging portion of the medical instrument between the first and second surfaces.