Updated 10 January 2018

Preoperative preparation

Three very important components of your preparation for your anaesthetic are your medical history, a physical examination, and if necessary, special investigations.

Your medical history

Your anaesthetist will have discussed your condition with your surgeon prior to the operation, and will also have carefully studied your medical file. So your anaesthetist will then probably know a lot about you even before the preoperative visit, and as a result the visit may be considerably shorter than the usual consultation, all that is necessary being to clear up any doubtful aspects of your medical condition.

Your anaesthetist will take your medical history directly from you; this involves getting details about your health, medical and surgical history and your social habits, and he or she will make use of and refer to the preoperative questionnaire that you may have been asked to complete when you were admitted to hospital. (This questionnaire should be completed in detail, and if there is anything that is not included or anything that the anaesthetist should know about in more detail, do this when he or she visits you).

The medical history is very important as it is on this and the examination to follow that your anaesthetist must decide whether you are fit for the anaesthetic, or whether your condition can be improved before undergoing the operation.

The preoperative consultation usually takes place the evening before the operation, but it may be more convenient for you and the anaesthetist to have this consultation on the morning of the operation. For short procedures when you are only admitted shortly before being transferred to theatre the anaesthetist may only be able to consult with you in the theatre.

The examination 

Once again your anaesthetist will be armed with knowledge obtained from your surgeon and medical file, and will not necessarily conduct the full examination you would get at a normal consultation with your doctor.

The examination will concentrate on your heart and lungs as the anaesthetic particularly affects these organs. If there is anything that is thought to be abnormal, the anaesthetist will conduct a more thorough examination, and may even refer you to a physician for a second opinion.

Special investigations 

If you are at all at risk for heart or lung problems, your anaesthetist will want investigations to be carried out. The most commonly required investigations are an x-ray of your chest and an ECG. If there is nothing that suggests that you have anything wrong with your heart or lungs, then it is obviously a waste of time and money to do these investigations.

Your anaesthetist also routinely checks that you are not anaemic and if there is any uncertainty, a blood test will be carried out. Other more sophisticated investigations will need to be done if you have some underlying medical condition.

Decision time 

Having all this information your anaesthetist will then advise you as to the effects the anaesthetic will have on you and what you can expect after the operation. Details of the planned anaesthetic can be discussed, and together you can work out what sort of pain management will be best suited to you, what should be done if you are nauseous, etc.


You must agree to the administration of the anaesthetic. However, you are entitled to know what you are agreeing to. Your anaesthetist will inform you about any complications that can be expected because of your medical condition and the type of anaesthetic and operation, but he or she will obviously not frighten you by telling you every possible complication.

Although modern anaesthesia is extremely safe, it obviously involves some risk and is not to be undertaken lightly. Your anaesthetist will therefore not tell you that there is a risk of you dying under general anaesthetic or that you could be rendered paraplegic by an epidural because the chances of these catastrophes occurring are very, very remote, and is not the sort of information one wants to hear the night before an operation.

Also, some complications cannot be predicted, for example, an allergic reaction to one of the drugs administered during the anaesthetic, and there is no point in bringing this to your attention. Nevertheless, if you are at risk for a specific complication, you are entitled to know this.

An example would be that if you have capped teeth or crowns, these might be damaged when your anaesthetist has to work in your mouth to ensure that your airway is not obstructed. If you have any concerns or if there is anything that you would like to know about your anaesthetic and its effects, you should feel absolutely free to discuss this with your anaesthetist at any stage before the operation.


After ensuring that you are fit for the anaesthetic your anaesthetist may then prescribe pre-operative medication that must be taken an hour or two before the operation. This usually takes the form of a sedative taken by mouth, which will make you drowsy, but more importantly will decrease your anxiety so that when you arrive in theatre you are calm and relaxed. Other drugs necessary for specific operations or specific medical conditions may also be prescribed. As a rule you should also take your usual medications, but this must be discussed with your anaesthetist.


One of the risks of an anaesthetic is that stomach contents can be regurgitated or that there may be vomiting, and you lungs will be contaminated with stomach contents. This can have very serious consequences. For this reason your anaesthetist will instruct you not to take any fluid for at least two hours or solid food for four to six hours before your operation.

If your operation is been carried out as an emergency and there is not time to allow your stomach to empty, your anaesthetist has to use special techniques to minimise the risk of aspiration, as it is called. But it is always best to keep risks to an absolute minimum, and pre-operative starvation is the best way to do this.

Read more:

Why is starvation important?
Hypertension and fasting


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