Why do you need to drink water when doing CT

CT is a very common examination in life. It is used to check many diseases, such as abdominal and gastrointestinal diseases. These diseases can usually be accurately detected by CT examination and then actively treated. However, when doing CT examination, people are often asked to drink a lot of water. Some people don’t understand that they are obviously very full after drinking so much water, and they want to vomit, but the doctor still asks them to drink water. I don’t know what’s going on.

Why do you need to drink water when doing CT scan?

When doing an upper abdominal CT scan, you need to drink water in most cases, except for cases such as pancreatitis and abdominal trauma. Not only should you drink water, but you should drink as much as possible.

The purpose of drinking water is to fully fill the intestines so as to distinguish the gastrointestinal tract from possible lesions. First of all, the wall of an unfilled gastrointestinal tract is very thick, which makes it easy to miss the organic lesions of the gastrointestinal tract itself. In addition, it is impossible to distinguish the soft tissue density shown by an unfilled gastrointestinal tract from the actual possible soft tissue density lesions. Therefore, drinking water during upper abdominal CT scan is needed and necessary. However, you should follow the doctor's advice on specific situations. It is best to do whatever the doctor tells you to do. Never say that the doctor tells you to drink more water and then eat something, because the food may affect the CT results.

What is the reason for drinking so much water when doing an abdominal CT scan?

The purpose of doing a good job of gastrointestinal examination before abdominal CT scan, in a nutshell, is to take a good look at the gastrointestinal tract to see if there is anything growing in the opening and to fill up the gastrointestinal tract.

1. Routine gastric scan: For our department, we drink warm boiled water. According to the guidelines, we drink 500-1000ml, so 2 cups are far from enough. Drink as much as possible to stretch the stomach wall, so that we can see if there is anything growing.

2. Routine scanning of the small intestine: The scanning standards for the small intestine are slightly complicated. I think many hospitals are unable to do it according to the standards. Generally, oral mannitol or cleansing enema can be performed. The purpose is to empty the contents of the small intestine. The suppository is also used to empty the feces in the large intestine, which is conducive to observing the intestine.

3. Colorectal scan: The colorectum is what we call the large intestine, which is filled with fecal tissue remaining after digestion and absorption. The enema is used to expel the feces, and injecting air into the anus is to fill the colorectum. The most commonly used method in our department is to inject clean water.

During abdominal CT scans, many clinicians are afraid of trouble and do not do gastrointestinal preparation. This adds difficulty to the work of our radiology department and can easily lead to misdiagnosis and missed diagnosis. When our staff in the radiology department ask patients to drink water, it is also to increase the detection rate of lesions and for the benefit of the patients. So even if you drink water but don’t feel full, you still need to drink.