Patent ID: 7258669

Claim:
A catheter for use under external ultrasound observation, the catheter comprising: an open hub at one end by which fluid can be supplied to or from the catheter, said fluid being either a gas or a liquid, a tubular body extending from said hub and opening at an opposite end of said catheter, said tubular body having a wall of a material that provides a relatively low ultrasound reflection during use and through which a fluid passes; and a marker providing a relatively high ultrasound reflection during use, wherein said marker extends helically along said tubular body and along its length so that an interruption in said fluid is readily ascertained by the difference in acoustic properties between said interruption and said fluid, and wherein said marker is extruded within the thickness of the wall as at least one closed gas-filled lumen, such that ultrasound energy is reflected externally of the body by the at least one closed gas-filled lumen.