A cannula assembly includes a housing and a cannula member connected to the housing. The cannula member has leading and trailing ends and defines a longitudinal axis. The cannula member further includes a main body, a seal adjacent the leading end and a flexible portion disposed between the main body and the seal. The seal is capable of receiving an instrument therethrough while maintaining a substantial sealed relation with the instrument. The flexible portion is configured to permit movement of the seal relative to the longitudinal axis during manipulation of the endoscopic instrument. The flexible portion of the cannula member may include one or more bellows. The one or more bellows may form a goose neck configuration. Alternatively, the one or more bellows define a series of ridges and grooves.
