A double kidney ultrasound does not require fasting, but if the bladder and ureters are to be examined, you will need to fast and hold your urine. Kidney ultrasound can find out whether there are changes in the shape and structure of the kidneys, which is of diagnostic significance for diseases such as hydronephrosis, kidney cysts and kidney stones. For kidney evaluation, checking color ultrasound is far from enough, but also need to check kidney function, urine routine and other items. Because in the early stage of many kidney diseases, patients first manifested as abnormal urine test, hematuria, proteinuria, as the disease progresses and aggravates, there will be impaired renal function, and the development of the middle and late stage will appear in the ultrasound above the morphology of the change. During the treatment of kidney disease, regular follow-up is also needed to monitor the changes of the condition.