Medical-surgical devices

1. A medical surgical device with a shaft made of plastics material, the shaft having a bore defined by a circular smooth inner surface, the bore extending along the length of the shaft, the shaft including a wall having a thickness defined between the inner surface and a concentric outer surface, gas bubbles being incorporated into and distributed in at least one region of the wall of the shaft between the inner and outer surfaces and having a size selected to increase the visibility of the shaft under ultrasound observation, the increase in the visibility of the shaft under ultrasound observation resulting only from the incorporation of the gas bubbles into the wall of the shaft.

2. The device of claim 1 , wherein the wall of the shaft consists of the plastics material and the gas bubbles incorporated and distributed therein.

3. The device of claim 1 , wherein the gas bubbles are distributed throughout the thickness of the wall along the length of the shaft.

4. The device of claim 1 , wherein the gas bubbles are formed in the wall of the shaft by the incorporation of hollow microspheres into the plastics material.

5. The device of claim 1 , wherein the gas bubbles are formed in the wall of the shaft by the adding of particles of a soluble material to a plastics melt used in forming the shaft.

6. The device of claim 1 , wherein the shaft is made by extrusion.

7. The device of claim 1 , wherein the shaft is made to be substantially transparent to ultrasound energy so as to enable material flowing along the bore of the shaft to be viewed by eye.

8. The device of claim 1 , wherein the device is an embryo replacement catheter where the passage of an embryo flowing along the catheter is viewable under ultrasound observation.

9. The device of claim 1 , wherein the gas bubbles have diameters in the range 1 .mu. to 50 .mu., and preferably in the range 5 .mu. to 10 .mu.

10. The device of claim 1 , wherein the gas bubbles may be spherical or of irregular shape.

11. The device of claim 1 , wherein the gas bubbles are formed in the wall of the shaft by adding a chemical foaming agent to the plastics material.

12. A catheter including a circular shaft having a wall made of a plastics material defined between an inner surface and an outer surface, the circular inner surface defining a bore extending along the length of the shaft, the shaft consisting of the plastics material and gas bubbles of a selected size incorporated throughout the thickness of the wall at at least one region of the shaft, wherein the visibility of the shaft under ultrasound observation is increased due to the gas bubbles having been incorporated throughout the wall of the shaft.

13. The catheter of claim 12 , wherein the gas bubbles are distributed throughout the thickness of the wall along the length of the shaft.

14. The catheter of claim 12 , wherein the gas bubbles are formed in the wall of the shaft by the incorporation of hollow microspheres into the plastics material.

15. The catheter of claim 12 , wherein the shaft is formed by extrusion from a plastics melt using an extrusion machine, and wherein the gas bubbles are formed by injecting a gas into the melt.

16. The catheter of claim 12 , wherein the gas bubbles are formed from particles of a soluble material added to a plastics melt used for forming the shaft.

17. The catheter of claim 12 , wherein the shaft is made to be substantially transparent to ultrasound energy so as to enable material flowing along the bore of the shaft to be viewed by eye.

18. The catheter of claim 12 , wherein the catheter is an embryo replacement catheter.

19. The catheter of claim 12 , wherein the gas bubbles are formed in the wall of the shaft by adding a chemical foaming agent to the plastics material.

20. A method of making a medical surgical device comprising forming a shaft of plastics material having a through bore extending along its length with a wall having a thickness defined by a smooth inner surface and an outer surface, and incorporating gas bubbles that have a selected size in at least one region of the wall of the shaft, wherein the visibility of the shaft under ultrasound observation is increased only due to the incorporation of the gas bubbles into the wall of the shaft.

21. The method of claim 20 , wherein the gas bubbles are distributed throughout the wall of the shaft.

22. The method of claim 20 , wherein the gas bubbles are formed in the wall of the shaft by the incorporation of hollow microspheres into the plastics material.

23. The method of claim 20 , wherein the gas bubbles are formed in the wall of the shaft by injecting gas into the plastics material as the shaft is being molded or extruded from the plastics material.

24. The method of claim 20 , forming the shaft to be substantially transparent to ultrasound energy so as to enable material flowing along the bore of the shaft to be viewed by eye.

25. The method of claim 20 , wherein the gas bubbles are formed in the wall of the shaft by adding a chemical foaming agent to the plastics material.

26. A method of increasing the visibility of a catheter having a shaft made of a plastics material and having a wall defined between concentric inner and outer surfaces, the inner surface defining a through bore extending along the shaft, the method comprising incorporating gas bubbles with a selected size to increase the visibility of the plastics material in the wall of the shaft as the shaft is being formed or extruded so that the visibility of the shaft under ultrasound observation is increased only due to the gas bubbles having been incorporated into the wall of the shaft.

27. The method of claim 26 , wherein the gas bubbles are distributed throughout the wall of the shaft.

28. The method of claim 26 , wherein the gas bubbles are formed in the wall of the shaft by the incorporation of hollow microspheres into the plastics material.

29. The method of claim 26 , wherein the gas bubbles are formed in the wall of the shaft by injecting gas into the plastics material as the shaft is being molded or extruded from the plastics material.

30. The method of claim 26 , wherein the gas bubbles are formed in the wall of the shaft by adding a chemical foaming agent to the plastics material.