Preparative fasting before contrast-enhanced computed tomography

Many hospitals have patients perform preparative fasting prior to contrast-enhanced computed tomography to prevent nausea, vomiting, and accompanying aspiration pneumonia. This policy has been regarded as reasonable because there are many side effects such as vomiting when ionic high-osmolar contrast media are used. Recent advancements in contrast media development, side effects such as nausea and vomiting have markedly decreased. However, fasting prior to the contrast-enhanced computed tomography examination is still customary. While debatable, it is not clear that fasting prior to the use of contrast media has a beneficial effect on the prevention of vomiting. On the contrary, excessive fasting can cause patient dissatisfaction, dehydration, and exhaustion. Therefore, before using contrast media, the duration of fasting should be determined based on consideration of the risks, benefits, and patient's comfort. In particular, to prevent dehydration, limitation of liquid intake during fasting is not recommended.