They are pretty much the same procedure except with an epidural they leave the catheter in so there is the option for continuous infusion or top ups of the drug where as the spinal is a much heavier block using different drugs they just don't leave the catheter in there most of the time. I haven't heard of them using an epidural for a c/s. Usually if someone already has an epidural (say from labour thats then converted to a c/s) they will top up the epidural using the spinal drugs to make a more dense block thus then making it a spinal anaethetic. Where I work you don't get a choice. Its an epidural for labour and spinal for a c/s. But I know we are weird compaired to other hospitals seeing as we are remote (we don't even have epidurals where you can mobilise) so other places might be different.