CT is a common imaging examination. When most people have problems with their body organs, they can make preliminary judgments through CT scanning. Among the types of CT examinations, enhanced CT is also a common one. Perhaps most people are not familiar with enhanced CT. In fact, enhanced CT (Computed Tomography) examination is a commonly used medical imaging examination method, widely used in clinical diagnosis and treatment. It is a further examination item of ordinary CT and requires injection of contrast agent during examination. Many people who have done it know that fasting and water restriction are necessary before the examination, but this often makes them feel strange. In fact, fasting and water restriction before the examination are mainly for the following reasons.
Firstly, fasting and water restriction can help reduce the absorption of contrast agents in the gastrointestinal tract. Enhanced CT requires the use of iodine contrast agents to improve image contrast and better observe the condition of organs and blood vessels. If the patient eats or drinks before the examination, the gastrointestinal tract will release digestive fluids, which contain many substances that can react with contrast agents, reducing their concentration and clarity, thereby affecting the quality and accuracy of the images.
Secondly, fasting and water restriction can also reduce the occurrence of certain complications. When patients undergo CT scans on an empty stomach, the stimulation of gastric and intestinal contents is reduced, reducing the risk of vomiting and aspiration. Although the contrast agents used in enhanced CT have been improved in terms of safety, some patients may experience adverse reactions such as nausea and vomiting due to discomfort. Therefore, fasting and water restriction before the examination can prevent patients from vomiting during the examination process, which can cause food to reflux into the airway and lead to suffocation. In addition, fasting can also prevent gastrointestinal peristalsis caused by diet, making organs and blood vessels more stable, which is beneficial for doctors to accurately judge and diagnose.
The duration of fasting and water restriction is determined based on specific circumstances, and it is generally recommended that patients fast for at least 4-6 hours before undergoing enhanced CT, and only drink a small amount of water. This period of time is sufficient to digest and absorb food in the gastrointestinal tract, reducing interference with contrast agents.
Of course, specific requirements regarding fasting and water restriction will also be subject to the judgment and guidance of doctors. In certain specific situations, such as children, pregnant women, or patients with abnormal blood sugar, it may be necessary to adjust the requirements for fasting and water restriction to ensure safety and effectiveness.
What else should I pay attention to when doing enhanced CT besides fasting and water restriction? Firstly, the medication should be discontinued. If patients with diabetes need to stop using metformin before performing enhanced CT examination, because metformin will not be metabolized by the liver, but mainly excreted through the renal tubules, and contrast agents also need to be excreted through the kidneys, which will increase the burden on the kidneys, leading to decreased renal function and tubular necrosis. Secondly, allergic constitution should be avoided. Due to the adverse reactions such as allergies caused by iodine contrast agents, people who are prone to allergies or suffer from allergies should avoid undergoing enhanced CT scans. At the same time, they should drink plenty of water compared to contrast agents. After undergoing renal metabolism examination, drinking plenty of water can promote urine, allowing urine to carry away excess contrast agents from the body and help with metabolism. Finally, renal insufficiency should be prohibited. Because contrast agents need to be metabolized through the kidneys, people with renal dysfunction or continuous decline in kidney cells should avoid undergoing this examination, which can increase the burden on the kidneys and even lead to kidney failure.
In short, fasting and water restriction before performing enhanced CT is to reduce the interference of gastrointestinal tract on contrast agents and improve the quality and accuracy of the examination. Before undergoing enhanced CT examination, patients should strictly follow the doctor's guidance for preparation and adhere to the corresponding fasting and water restriction requirements. If you have any uncertainty or doubts, you should consult a doctor in a timely manner.