tonsillectomy is done under a general anaesthetic.
you can ask to be present in the room when the child goes to sleep. usually the anaesthetist will use a mask with anaesthetic gas to get the child to sleep and then get u to leave. they will then put in a breathing tube to protect blood from going into the airway and to keep the child oxygenated and anaesthetized.
the child will also get medication to help with the pain both during and after the procedure. the tonsils are very sore after the operation and the child may not be able to take more than just fluids for a few days depending on how swollen the tonsils are.