The causes of renal vascular malformation and compression can be divided into congenital and acquired, and it is difficult to distinguish congenital renal vascular malformation from variation. Usually "deformity" refers to abnormal morphological structure and pathological changes with dysfunction; Variation means that only the morphological structure is abnormal, which does not affect the organ function and does not cause pathological changes. Some renal vascular variations may also cause pathological changes under certain circumstances, and renal vascular malformations may not necessarily constitute pathological changes. For example, some renal arteriovenous fistulas with small branches generally do not affect health, while when a female patient is pregnant, the blood flow increases, which may lead to heart failure and high cardiac output. The etiology of congenital renal vascular malformation is not clear, which may be caused by some virus infections or DNA recombination errors during cell division during embryonic development. Acquired factors include trauma and tumor.