Nowadays, health checkups are becoming more and more common, and in clinical practice, health checkups generally require fasting. Drinking water will have the following effects on the checkups in most cases: First, it will affect the urine routine checkups, and after drinking water, the urine will be diluted, which may affect the urine specific gravity and the examination of the organic fraction in the urine, such as a decrease in the number of red blood cells and white blood cells. Interfere with the examination of blood sugar, liver function, blood lipids and other items. Third, when doing abdominal ultrasound examination, after drinking water, the stomach and intestinal tube distension interference, making the liver, gallbladder, pancreas, spleen and other examination is not satisfactory, it is not easy to see what lesions. Therefore, the general physical examination requires an empty stomach. Of course, there are some cases such as checking the bladder or gynecological uterine adnexal examinations, and doing ultrasound often requires drinking water and holding urine. So care should be taken to schedule when to drink water and when not to drink water.