Abstract: A medical device which has a connection between a signal generating device and a hollow probe, the connection providing a smooth air conduit from the signal generating device to the hollow probe. The medical apparatus includes the probe having a characteristic which is useful to assist with the positioning of the probe in a human or animal body, and an information encoding component on the probe, a selected value of the information encoding component being corresponding to the characteristic of the probe. An interrogating device interrogates the information encoding device.

Abstract: A medical needle 1 including a tubular stylet 30 has one or more apertures 32, 32.sup.A-F at its distal end 16, which are located and dimensioned to prevent occlusion by body tissue. The aperture may be formed by a convexly sided, transverse channel 32.sup.B cut into the needle wall 19 or can face rearwardly. Alternatively, a plurality of spaced, longitudinal slits 32.sup.C or circular apertures 32.sup.D can be provided by laser perforation. The needle can be associated with an outer cutting sheath 34 housing a trocar 21 for use in ultrasound imaging. In further embodiments, the needle can constitute the stylet of an aspiration biopsy needle (FIG. 8) or a needle assembly can comprise a stylet 130 within a cannula 140, the stylet having an expanded distal tip 133 of cross-section complimentary to that of the cannula bore so as to prevent occlusion of the cannula end by tissue (FIG. 7).

Abstract: A needle inserted into body tissue is rendered visible to a Doppler ultrasound imager by generating a longitudinal oscillation of the fluid column in the needle barrel by means of a transducer which is energized by a signal of frequency 100 Hz to 2 kHz, for example. An image of the needle tip is displayed on a screen.