Pre-operative fasting in adults and children: clinical practice and guidelines

Overview

This article reviews the evidence behind pre-operative fasting and compares current guidelines for adults and children. Fasting aims to reduce the risk of pulmonary aspiration during anaesthesia, but in practice patients are often starved for far longer than recommended.

Why prolonged fasting matters

Unnecessarily long fasting causes thirst, hunger, discomfort, dehydration and, particularly in children, low blood sugar and irritability. It does not reduce aspiration risk further and may worsen the patient's experience and recovery.

Current recommendations

Guidelines agree that clear fluids can be taken much closer to surgery than solid food, and that milk and light meals fall between the two. Recommendations for children are more liberal, with growing support for allowing clear fluids until shortly before anaesthesia. Carbohydrate-containing drinks before elective surgery are supported as part of enhanced recovery pathways for suitable patients.

Patients needing individual assessment

Standard rules may not apply to patients with delayed gastric emptying, such as those with diabetes, obesity, pregnancy, bowel obstruction or recent trauma, or to emergency cases. Gastric ultrasound is described as a tool to assess stomach contents when there is doubt.

Putting guidelines into practice

The authors emphasise clear patient instructions, flexible fasting times when theatre schedules change, and institutional protocols that actively encourage drinking rather than blanket nil-by-mouth orders.