Spinal
Combined spinal / epidural
With an epidural, the epidural needle is inserted only as far as the epidural space. This is a 4mm space located just outside a layer of tissue called the 'dura mater'. The dura mater tissue encases the spinal cord and spinal fluid.
Once the needle is believed to be in the correct location, a fine, flexible, hollow tube or 'catheter' (about the width of fishing line) is passed through the hollow needle, so that the end of the tube rests in the epidural space. The needle is then removed leaving the catheter in place. The catheter is about 90cm long and the remainder of it is eventually taped in place, up the length of the woman's back.
The anaesthetic medication(s) chosen by the anaesthetist are injected down the tube to 'bathe' the nerves that lead to the woman's uterus and lower body, to numb them. The full effect of the medications will take about 10 to 30 minutes.
When using an epidural for a Caesarean birth, more concentrated (and often different mixtures) of medications are given, compared to if the epidural is just used for pain relief in labour. If an epidural is already in place before the Caesarean is decided upon, then more medications will be added (or 'topped up') to make the epidural more effective for the operation.
After the Caesarean, once the initial dose of medication has worn off (about 1 to 2 hours), pain-relieving medications (such as the narcotic Pethidine) can be administered down the epidural catheter for pain relief. This is would usually continue for about 24 to 48 hours after the operation.
You may wish to read more on this in
epidurals for Caesarean.
Spinal
With a spinal anaesthetic, instead of the needle being inserted as far as the epidural space, the fine, hollow, spinal needle is pushed in a little further to actually pierce the 'dura mater' layer of tissue (the dura mater being the tissue that encases the spinal cord and spinal fluid).