In the treatment of parastomal hernias, whether intestinal or urological stomas, there is often a preoperative lack of knowledge about the exact type of stoma and the relevant uniqueness that must be taken into account for the treatment. In this chapter, the anatomy of the most important types of stoma is described in detail. In particular, the anatomy around the ileum conduit, with the displacement of the ureters, the altered mesentery and the lack of peritoneum after cystectomy is described and presented with a summarizing illustration.