A needle assembly comprises a metal needle (1) with a hub (13) and a marker in the form of a bubble-filled plastics rod (2) inserted within the needle. The rod (2) makes the assembly more visible under ultrasound observation when confirming correct placement of the needle (1) and is subsequently removed when correct placement has been confirmed. A fluid (3) is placed between the outside of the rod (2) and the inside of the needle (1) to improve acoustic coupling between the needle and the rod. Alternatively, a rod (72) is stretched during insertion and allowed to expand into close contact with the inside of the needle after insertion.
