Caudal blocks

This information sheet from Great Ormond Street Hospital explains about caudal blocks. A caudal block is a pain-killing injection at the base of the back which is done after your child is asleep.

When is a caudal block a good idea?

A caudal block gives pain relief for three to 12 hours. It numbs the lower half of the body (from the belly button downwards) and so may be used for surgery on the lower tummy, groin or legs. A caudal block is combined with general anaesthesia so your child will still be asleep for their operation, but they can have less anaesthetic and will need lower doses of other painkillers.

How is a caudal block performed?

After your child is asleep they will be turned on their side and their lower back will be carefully cleaned. Under sterile conditions the anaesthetist will insert a small needle into a space at the base of the back and inject the painkillers. The needle is then removed.

Is a caudal block safe?

Caudal blocks have been used regularly in children for the last 30 years and have an excellent safety record. Several large studies in the UK and abroad have also shown that caudal blocks are very safe.

Are there any side effects?

„„Failure – in a small number of children it may not be possible to perform the caudal block or it may not work. In this case your child will be given other painkillers to keep them comfortable.

„„Numbness/weakness – for the three to 12-hour period that the caudal block is working, your child may have numb, weak or tingling legs and they may have difficulty urinating. You should supervise them closely if they are crawling or walking, and keep them away from anything hot or sharp as they will not feel pain in the same way as normal. A small number of children may need a catheter into the bladder to help them urinate. All of these effects will wear off as the block wears off.

„„Bleeding/infection/nerve damage – as mentioned above, caudal blocks are very safe and the risk of bleeding or nerve damage is extremely low. Infection is very unlikely as they are done under sterile conditions in an operating theatre.

„„Local anaesthetic toxicity – as with any drug, toxicity (too much drug) is a possibility. We stay within accepted upper dose limits but if the local anaesthetic gets into the blood stream it is possible to see adverse effects, especially on the heart rhythm. There are established guidelines for dealing with this extremely rare complication.

Are there any reasons my child shouldn’t have a caudal block?

If your child has any abnormalities of their back or spine then you should tell the anaesthetist when he sees your child before their operation, as a caudal block might not be suitable for them. If they have blood clotting abnormalities this may also mean they cannot have a caudal block.

Compiled by:
The Department of Anaesthetics in collaboration with the Child and Family Information Group.
Last review date:
July 2017