Cancer tests and anaesthetic

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Anaesthetic is used to reduce or take away pain. Learn more about anaesthetics, how they are given and why you might need an anaestetic during a procedure.

Key points

  • Anaesthetics are used to help manage pain.
  • A local anaesthetic numbs a specific part of your body, while a general anaesthetic usually works on your whole body and puts you to sleep.
  • If you are having a general anaesthetic, you will need to stop eating 8 to 12 hours before your procedure.
  • Once the anaesthetic starts working and you are asleep, the health-care team will start the procedure.
  • After a general anaesthetic, you will wake up in a recovery room attached to monitors. You may feel sleepy, grumpy or unsteady for a few hours after the procedure.

What is anaesthetic?

For some tests, you will be given a type of medicine called an anaesthetic (say: AN-us-theh-tic). Anaesthetics are used to reduce or take away pain. They can be either local or general.

A local anaesthetic works to numb a part of your body. It might be a cream, a patch, or an injection (needle).

Local anaesthetics will usually be given by a doctor or nurse in a regular hospital room or in a room in a clinic. Normally, you do not need any special monitoring with a local anaesthetic. The test will happen once the anaesthetic has started working and the skin on that body part is numb (usually about half an hour). Because of the anaesthetic, you will feel less pain, or sometimes none at all.

A general anaesthetic works on your whole body. It is sometimes called a sedative. It makes you relaxed and sleepy, and you won’t remember the procedure at all. It is given by a doctor called an anaesthesiologist (say: AN-us-thee-zee-ol-uh-jist). It can be given through an IV (intravenous, a tube into a vein) or as a gas that you breathe in through a mask.

You will need to stop eating eight to 12 hours before a general anaesthetic. We call this "NPO" meaning "Nil Per Os", which is Latin for "nothing by mouth". Your health-care team will give you more information about how to prepare. You will usually be allowed to eat once you wake up from the general anaesthetic, although it may take some time until you feel like eating.

Usually a general anaesthetic is given in a procedure room. You will be attached to machines called monitors that will track your blood pressure, breathing rate and heart rate to make sure that you are okay while you are having the anaesthetic. The doctors and nurses will also monitor you very carefully. Once the anaesthetic is working and you are asleep, the test will happen. You will not feel any pain and you will not remember the procedure.

After a general anaesthetic, you will wake up in the Post-Anaesthetic Care Unit (PACU) or a recovery room. You will still be attached to the monitors. You will not remember anything that happened while you were asleep. You may feel very sleepy, grumpy or unsteady for a few hours after you wake up. Your doctors and nurses will explain any side effects to watch for and will monitor you carefully.

Last updated: September 3rd 2019