Intravenous urography (IVP) is a diagnostic test to visualize the kidney, ureter and bladder by intravenous injection of contrast agent, which is a common test method in urology and gynecology, characterized by low pain and high diagnostic efficiency, especially for urinary stones and urinary excretory function is a better means of examination with authoritative diagnostic purpose. In order to ensure the accuracy and safety of diagnosis, it is necessary to prepare for the examination. 1, patient preparation 1, three days before the imaging for iodine allergy test, iodine allergy test positive people can not carry out the examination. 2, 2-3 days before the imaging do not eat easy to produce gas (such as tofu, milk) and dregs of food, and forbidden to take bismuth and drugs containing calcium or heavy metals, prohibited impermeable X-ray drugs. 3, the night before the examination, take oral plant laxatives (such as clover leaf or castor oil) or do a clean enema to clear the intestinal contents, one day before the imaging into a less dregs diet to avoid the intestinal contents and the overlap of the renal pelvis and calyces, ureter and bladder, affecting the observation and analysis. 4, three hours before the examination can not drink water and into the liquid food (can eat a small amount of dry food such as cake, bread, etc.), in order to make the blood concentration, the kidney secretion of urine containing contrast agent concentration increased, display more clearly. 5. Urinate before the examination to make the bladder empty. 6.Before iodine injection, the necessary treatment should be performed according to the pharmacopoeia. II. Contrast agent preparation Contrast agent is 76% ionic or corresponding iodine content of non-ionic contrast agent, the dosage of which is 20-40ml.