Caudal block for pain relief after surgery

A caudal block is a single dose of a local anaesthetic solution given under general anaesthetic, while your child is asleep. An experienced anaesthetist injects the solution into the caudal space, an area in the pelvis below the bottom of the spine, close to the nerves that supply the area of surgery in the lower part of the body.

The local anaesthetic solution temporarily ‘blocks’ or numbs the nerves from the site of surgery, preventing pain messages getting through to the brain. The local anaesthetic solution can also include a small amount of another medicine which also helps to relieve pain.

Caudal blocks are generally used for surgery, including day-case surgery, on the lower tummy, groin or legs. Advantages of a caudal block include better pain relief and using much lower doses of other pain medicines like morphine that can have problematic side effects.

The anaesthetist will assess the balance of benefits and risks for your child, taking into account their general state of health and the type of surgery they will have, when deciding whether to offer or recommend a caudal block.

Most children can have a caudal block but it may not be suitable if your child has any of the following:

• Broken or infected skin on the lower back or bottom, or certain infections elsewhere

• Previous allergic reaction to local anaesthetic medicine

• Some kinds of previous spinal surgery or spinal problems

Problems with blood clotting, or if they are taking anti-coagulants (blood thinning) medicines If a caudal block is not suitable for your child, a different method of pain relief will be used to keep your child comfortable.

A caudal block normally gives pain relief for 3 to 12 hours after surgery, although it may still be necessary to give other painkillers as recommended and prescribed by GOSH during this period.

The temporary reduction in sensation due to caudal block may be a factor causing a longer time than usual before needing to pass urine after surgery; staff will therefore always check that your child has ‘had a wee’ before discharge home.

Your child may also have a numb or heavy sensation, or be slightly weak, in the lower part of the body due to the expected effects of the local anaesthetic solution. You should therefore 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 during this period.

Caudal blocks are very safe and serious problems are all very rare. Nevertheless, problems can occur so it’s important to be aware of them. Sometimes we find it is not possible to perform a caudal, or that the block does not work as well as expected; if this happens, a different pain-relieving medicine will be given to keep your child comfortable.

Very rare problems can include bleeding or infection at the caudal block injection site, high levels of local anaesthetic in the blood called ‘local anaesthetic toxicity’, and damage to the nerves causing numbness or weakness for a short period that gets completely better, or, even more rarely, that does not recover.

More detailed information on interpreting and understanding risks can be found in the ‘Your child’s general anaesthetic’ information sheet and in the ‘Understanding risk’ information sheet – both are available from the Anaesthetic PreOperative Assessment Clinic (APOA) and on our website. In addition, for further information on how your child’s pain will be managed after an operation or procedure at GOSH, please ask for a copy of our general ‘Pain relief after surgery’ information sheet, available from ward nurses, the Pain Control Service, the Pals Office, APOA, and also on our website.