Abstract: An embryo transfer catheter or other medical device has a shaft extruded with two layers. The outer layer is relatively thick and contains gas bubbles sufficient to increase the visibility of the catheter under ultrasound observation but with a density that allows material within the catheter to be viewed by the eye. The inner layer is relatively thin and is free of bubbles so that it provides a smooth bore to the catheter.

Abstract: An embryo transfer catheter or other medical device has a shaft extruded with two layers. The outer layer is relatively thick and contains gas bubbles sufficient to increase the visibility of the catheter under ultrasound observation but with a density that allows material within the catheter to be viewed by the eye. The inner layer is relatively thin and is free of bubbles so that it provides a smooth bore to the catheter.

Abstract: An embryo replacement catheter has a flexible extruded shaft of a transparent polyurethane with a bore extending along its length. Gas bubbles of a diameter in the range 5.0 mu. to 10.0 mu. are incorporated into the thickness of the wall of the shaft by adding gas during extrusion. The bubbles are selected to increase the visibility of the catheter under ultrasound imaging whilst still enabling material flowing along the catheter to be seen. The inventive catheter is not confined to embryo replacement catheters.

Abstract: A needle assembly of a metal shaft (10, 10?) and an outer plastics sleeve (12) is made by extruding the sleeve onto the outside of the shaft. The sleeve contains gas bubbles (13), preferably with a size in the range 5 ? to 10 ?, to increase the ultrasound visibility of the assembly. A sharp, penetrating tip (18) may be formed on the shaft either before or after the sleeve is extruded on the shaft. The metal shaft (10) may be supplied to the extruder 1 to 5 in a continuous length and cut to the size of the needle assemblies after extrusion of the sleeve (12). Alternatively, pre-cut lengths of metal shafts (10?) could be supplied to the extruder 1? to 5?, the sleeve being cut between the shafts after extrusion.

Abstract: An embryo transfer catheter or other medical device has a shaft extruded with two layers. The outer layer is relatively thick and contains gas bubbles sufficient to increase the visibility of the catheter under ultrasound observation but with a density that allows material within the catheter to be viewed by the eye. The inner layer is relatively thin and is free of bubbles so that it provides a smooth bore to the catheter.

Abstract: An embryo transfer catheter or other medical device has a shaft extruded with two layers. The outer layer is relatively thick and contains gas bubbles sufficient to increase the visibility of the catheter under ultrasound observation but with a density that allows material within the catheter to be viewed by the eye. The inner layer is relatively thin and is free of bubbles so that it provides a smooth bore to the catheter.