13 September 2004

Obstetric anaesthesia

Many anaesthesiologists supply an obstetric epidural service. This may be simply for controlling the pain of labour, or may be for a Caesarean Section.


Many anaesthesiologists supply an obstetric epidural service. This may be simply for controlling the pain of labour, or may be for a Caesarean Section. Alternatively, a Caesarean Section may be carried out under a spinal anaesthetic or a general anaesthetic.

Spinal or epidural anaesthetic
Both these types of local anaesthetic block are meant to anaesthetise the lower part of your body and abdomen by anaesthetising the last part of the spinal cord and the nerve roots that leave from there to supply your lower body. The technique is as follows:

  • Before the start your anaesthesiologist will put up a “drip”.
  • You will be placed in a sitting position on the edge of your bed or the theatre table with your back exposed.
  • Your anaesthesiologist will then clean your skin with an antiseptic solution (which will probably feel very cold!)
  • A small amount of local anaesthetic will be injected below the skin of your back where the spinal or epidural needle is to be inserted.
  • For a spinal your anaesthesiologist will then insert a very thin needle between the spines of your lumbar vertebrae for about 7-10 cms until it penetrates the membrane surrounding the spinal cord, and cerebrospinal fluid comes out of the needle.

    He / she will then inject about 2-3 ml of local anaesthetic into this space. You will feel the effect starting within minutes, and in about 10 minutes you will be sufficiently anaesthetised for the surgeon to operate. The spinal will last for about 2 hours or more, depending on which type, and how much, local anaesthetic was used.

  • For an epidural your anaesthetist uses a thicker needle, also inserted between the spines of your vertebrae. After it inserting about 5 cms, he will remove the styllete from inside the epidural needle and attach a syringe filled with either air or saline. He /she then advances the needle a few millimetres at a time, stopping to press gently on the syringe attached to the needle. Before reaching the epidural space there will be resistance on the end of the syringe, but when the tip of the needle enters the space around the spinal cord (the epidural space) this resistance will disappear.

    The syringe is then disconnected from the needle and a long thin catheter is inserted through the needle and about 5 cms up the epidural space. The needle is then withdrawn over the catheter, so that only the catheter is left in the epidural space, and this is then strapped to your back. Local anaesthetic is then injected through the catheter, the amount depending on whether it is just analgesia for labour that is required, or full anaesthesia for a Caesarean Section.

    An epidural takes longer to work than a spinal, and the full effect may not occur for anything from 30-40 minutes. The big advantage of leaving the catheter in the epidural space is that more local anaesthetic can be injected later, either to deepen the level of anaesthetic, or to provide pain relief for long periods. An epidural usually lasts for 4-6 hours after the initial injection.

  • In neither case will you lose consciousness, but you may feel drowsy. If the operation becomes distressing for you, your anaesthesiologist can inject some sedative intravenously to remove your anxiety or even put you into a light sleep.
  • An epidural for Caesarean Section is a particularly satisfactory and joyful experience as the mother can hold her baby within a few minutes of its being delivered.

Read more:
Caesarean section
More women want C-sections


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