1 = General anaesthetic: the administration by a doctor of an agent to produce unconsciousness

2 = Epidural or caudal anaesthetic: the injection of a local anaesthetic into the epidural space

3 = Spinal anaesthetic: the injection of a local anaesthetic agent into the subarachnoid space

4 = General anaesthetic and epidural or caudal anaesthetic

5 = General anaesthetic and spinal anaesthetic

6 = Epidural or caudal, and spinal anaesthetic

7 = Other than 1 to 6

8 = Not applicable

9 = Not known

null = Not applicable (from 1990-91 to 1994-95)