Eating and drinking before an operation – the facts

June 15th 2018

The cancellation of surgery across the NHS is a much-debated topic. Cancellations can happen for many reasons, but a common cause and one which is completely unavoidable is this – patients ignoring advice to fast before their operation.

All patients receive information about what they can and cannot eat and drink before they come to hospital for their treatment.  As a general rule, if your surgery involves a general anesthetic you will be told that you cannot eat or drink anything for a specific period before your operation. This varies depending on the procedure, but is usually six to eight hours for food and two hours for fluids – and it is best to err on the side of caution and restrict fluids to water only.

Some procedures which might involve a local anaesthetic, such as endoscopy, also require patients to fast beforehand.

Why do I need to fast?

When you are under anaesthetic the reflexes we rely on to function are temporarily shut down. There is a risk of vomiting or regurgitation if there is anything in your stomach. If this happens when you are under anaesthetic the regurgitated stomach contents could spill into your lungs and affect your breathing – it can also cause damage to your lungs and may cause death in rare situations.

What should I avoid?

The information you receive from us before your operation will contain details about your fast, and it is essential that you follow these instructions to the letter. No food means no food for the period requested – not even chewing gum or nicotine gum or sweets. You may be advised to avoid fluids which contain milk, as fats and proteins could damage your lungs if regurgitated. Clear fluids are recommended, such as water and black tea or coffee without sugar. Under no circumstances should alcohol be consumed during the fasting period.

What if I have a medical condition?

If you have a medical condition such as diabetes, which requires you to eat on a regular basis, please let your medical team know so they can offer specific advice.

What if I have been given medication to take before my operation?

You will have received instructions about how and when to take your medication and it is important that these instructions are followed. For example, if you are undergoing an endoscopic procedure which involves taking a bowel preparation, do not use it to ‘wash down’ your evening meal the evening before your procedure – especially if you have been advised not to have that evening meal in the first place!

What if I am hungry or thirsty?

Fasting is not pleasant, but it is necessary so we would ask all patients to stick with the fast to avoid having their operation cancelled. If you are very thirsty in the final two hours before surgery you may be allowed sips of water – by this point you are likely to have been admitted for your treatment and one of our team will be able to advise and oversee.

To recap:

  • Follow instructions to fast to the letter
  • You need to fast to ensure that your operation can proceed safely
  • If you do not fast your operation will be cancelled
  • Let the medical team know if you have a condition which makes fasting difficult
  • Fight the urge to eat or drink during the fasting period – a few uncomfortable hours are worth it to have potentially life-changing surgery

If you have any questions or are unsure about fasting, contact the number in your pre-operation information pack or contact your local NHS treatment centre directly.