General Anaesthesia (GA)

General anaesthesia is a state of controlled unconsciousness during surgery.
Many patients find it convenient to sleep during surgery and only wake up when the operation is complete. General Anaesthesia has a high level of safety and comfort and is suitable for most operations
It has, however, some disadvantages such as requirement for injection of multiple anaesthetic drugs, requirement for airway protection and artificial ventilation, sickness after waking up. Depending on the type of operation there may be pain after waking up with need for powerful painkillers. GA comes with rare but serious risks such as stomach contents entering lungs, awareness during surgery, tooth damage and airway problems. It also takes some time - hours to days - to recover fully from a 'GA'

Sedation

Sedation is a state of mild to moderate relaxation and sleepiness during surgery without being unconscious. The surgical area will be numbed separately so that you will not feel pain during surgery.
You will be conscious and able to communicate but relaxed and without the anxiety you may have prior to your operation
Sedation avoids many side effects and risks of a GA and recovery is much quicker. It is suitable only for some operations.
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Regional Anaesthesia (RA)

Examples are spinal or epidural anaesthesia or nerve blocks such as plexus blocks.
'RA' will numb parts of the body (e.g. a limb) so surgery can take place without pain. You will be conscious (or have optional sedation) without feeling discomfort during surgery. RA can be combined with a GA.
'RA' has its own advantages and disadvantages. There is no need for airway protection and artificial ventilation. Pain control after surgery is much better because the area remains numb for longer, so there is less need for strong pain killers. Recovering from 'RA' is quicker as it does not effect the brain; however, the affected limbs will remain numb and heavy for several hours after surgery so it will take some time to be able to fully move.
'RA' has risks and side effects as well. A targeted injection is necessary which can rarely lead to nerve function problems or even longer term damage. Sometimes RA doesn't fully numb the surgical area or it may be difficult to administer, in which cases a GA would be done.
Your anaesthetist will discuss the advantages and disadvantages of these forms of anaesthesia and will decide with you which may the best for you individually.