A surgical access port includes an access member defining a longitudinal axis and having an interior wall defining a longitudinal opening adapted for passage of a surgical object, an object seal disposed in mechanical cooperation with the access member and configured to create a substantially fluid-tight seal around a surgical object inserted through the object seal and a centering mechanism mounted to the access member proximal of the object seal. The centering mechanism includes at least one centering element extending at least in a general longitudinal direction within the longitudinal opening, and defining proximal and distal longitudinal end segments. The at least one centering element is positioned and dimensioned to engage the surgical object during passage of the object through the longitudinal opening to normally bias the surgical object into general alignment with the longitudinal axis. A locking member is mounted to the distal longitudinal end segment of the at least one centering element. The locking member is adapted for longitudinal movement relative to the longitudinal axis when the surgical object is in generally aligned relation with the longitudinal axis. The locking member is dimensioned to engage the interior wall of the access member upon asymmetrical manipulation of the surgical object relative to the longitudinal axis to substantially lock the centering mechanism and prevent further asymmetrical manipulation of the surgical object until the surgical object is returned to the generally aligned relation with the longitudinal axis under the bias of the at least one centering element.
