Retroperitoneum usually refers to the retroperitoneal space, the area below the diaphragm, above the pelvic diaphragm, and between the posterior abdominal wall and the posterior retroperitoneum. Peritoneum refers to a layer of plasma membrane in the abdominal cavity of higher vertebrates, mostly composed of mesothelial cells, including most of the organs in the abdominal cavity, which can also secrete mucus to moisten the surface of the organs to reduce organ friction. The peritoneum is divided into the anterior peritoneum and the posterior peritoneum, of which the retroperitoneal space is referred to as the retroperitoneum, and common retroperitoneal tissues include the descending part of the duodenum, adrenal glands, kidneys, pancreas, and part of the vasculature and nerves. Retroperitoneal space organs and tissues are more, tumors and trauma and other diseases are not uncommon, but also because of the stretch of the gap is large, bleeding or infection are easy to spread, the tumor is also more and larger, such as the discovery of abnormalities patients need to cooperate with the doctor to check the treatment at an early stage.