An adjustable sheath assembly sized to accept a medical instrument and adapted for insertion into a body of a patient for maintaining a passageway therein. The device includes a first hollow member having a first length, and a second hollow member having a second length, the first and second members being coaxially joined together through a length adjustment element. At least one of the first and second hollow members is sized to accept a medical instrument. The length adjustment element allows for the length of the sheath assembly to be fitted to bodies of various sizes by adjusting the length prior to insertion into the patients body. A properly adjusted length ensures that at least a portion of the sheath assembly remains outside of the patients body.
