Preoperative fasting of patients for theatre, Royal Hospital for Children
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Preoperative fasting of patients for theatre, Royal Hospital for Children

What's New


  • Title change from Preoperative fasting of elective patients to Preoperative fasting of patients for theatre.
  • Update to the Emergency Surgery section with guidance on "Drink Until Call"


This guideline aims to:

  • Decrease the incidence of prolonged starvation in patients undergoing elective surgery at
    the Royal Hospital for Children.
  • Increase patient and parental comfort and satisfaction as a result of minimised fasting times.

The risk of pulmonary aspiration must be balanced with the risk of discomfort, hunger, thirst, dehydration and hypoglycaemia. These guidelines are written in the context of recent national and international publications and recommendations (1).


This guideline is for use all ASA 1 & 2 patients undergoing elective surgery.

Patient exclusions from this protocol include children who require longer for gastric emptying to occur. Such patients may include:

  • Renal failure
  • Gastro-oesophageal reflux disease (on treatment or under investigation)
  • Enteropathies
  • Oesophageal strictures/patients booked for oesophageal dilatation
  • Achalasia
  • Diabetes mellitus
  • Patients undergoing emergency surgery*

If you have any doubts about the fasting times for a patient, please contact their anaesthetist.

The anaesthetist can be identified from the weekly rota or by phoning theatre reception on 84344/84345.

*Fasting guidance for patients undergoing emergency surgery should be decided by the anaesthetist on-call for Theatre 6. Their suitability for this guidance will depend upon their surgical and clinical condition. The on-call anaesthetist can be contacted on:

  • 0141 452 4342 / extension 84342 (Registrar)
  • 0141 452 4343 / extension 84343 (Fellow/Senior Registrar)
  • 0141 452 4378 / extension 84378 (Consultant)


This guideline is for use by all health professionals in the Royal Hospital for Children, Glasgow who are involved in preparing patients for surgery. Administrative staff involved with communicating with patients and carers prior to procedures should also be familiar with this guideline.


Patients undergo fasting to minimise the risk of aspiration of gastric contents under anaesthesia.  Over-fasting, especially in neonates and young infants, can lead to hypoglycaemia, thirst, hunger, irritability and dehydration.  This can reduce patient comfort and make building rapport or securing venous access more difficult.  Patients and parents should actively be encouraged to maintain hydration up until the requested fasting time for clear fluids to minimise these side effects.  Ensuring a child is adequately hydrated prior to a procedure is as important as correct fasting.

These guidelines balance the risk of aspiration with the risk of over-fasting.  Children should be fasted for the minimum time possible.  Although traditional guidance recommended 6 hours for solids, 4 hours for breast milk and 2 hours for clear fluids, recent evidence has shown that drinking clear fluids until 1 hour before surgery does not increase the risk of aspiration (2). Gastric content reduces exponentially after clear fluids with the median half-time less than 30min (3, 4).  When glucose is included in the clear fluid, then gastric emptying is significantly quicker (2).


Clear fluids include water, diluting squash, ready diluted juice (e.g. Fruit Shoot®, Ribena®).  Selected ice lollies are also allowed (not milk- or chocolate-based).

Clear fluids do not include milk, formula milk, pure fruit juice and fizzy drinks.


On admission to the Day Surgery Unit or ward, patients should be offered a clear drink or ice lolly of their choosing.  

Morning Elective List



Afternoon Elective List

Patients under the age of 18 months can be offered a few drops of 24% sucrose orally or onto a dummy to assist with pacification if required.  The Oral Sucrose guidelines can be accessed here


Families and staff should be given accurate and consistent information relating to fasting.  Written guidance should be given to patients and parents when they attend pre-assessment clinic, and/or when their booking letter is sent out.  The importance of providing food up until the fasting time (where practical) and clear fluids until sending must be clearly explained to the parents & guardians.

Emergency Surgery

Drink Until Call

Please encourage patients on the emergency list to have sips of clear fluid, preferably sugar containing fluid until the anaesthetic team from the emergency theatre call the ward requesting that fluids are stopped, this call will be approximately 1 hour prior to the anticipated time the patient will go to theatre. It is important that the patient drinks sips and not large volumes of fluid. This applies to patients within the ED, RHC wards and all hospitals referring to RHC for surgery.

There are a few exclusions including patients with bowel obstruction, intracranial bleeding and testicular torsion, these patients will have oral fluids withheld from the time they are scheduled for theatre.

If you need to confirm that your patient should Drink Until Call, please phone Theatre 6 Dect 84358 or the duty anaesthetist Dect 84342 / 84343

  1. Thomas M, Morrison C, Newton R, Schindler E. Consensus statement on clear fluids fasting for elective pediatric general anesthesia. Pediatric Anesthesia  2018;28:411-414.
  2. Kelly CJ, Walker RW. Perioperative pulmonary aspiration is infrequent and low risk in pediatric anesthetic practice. Pediatr Anesth. 2015;25:36-43
  3. Andersson H, Hellström PM, Frykholm P. Introducing the 6-4-0 fasting regimen and the incidence of prolonged preoperative fasting in children. Pediatr Anesth. 2018; 28 (1); 48-52
  4. Schmitz A, Kellenberger CJ, Liamlahi R, et al. Gastric emptying after overnight fasting and clear fluid intake: a prospective investigation using serial magnetic resonance imaging in healthy children. Br J Anaesth. 2011;107:425-429.
Editorial Information

Last reviewed: 10 August 2022

Next review: 25 February 2023

Author(s): Alyson Walker, Consultant Paediatric Anaesthetist

Author Email(s):

Approved By: Paediatric & Neonatal Clinical Risk & Effectiveness Committee

Reviewer Name(s): Dr Shane Campbell, Consultant Paediatric Anaesthetist

Document Id: 661