The complex retroperitoneum technically includes anything that is not suspended on a mesentery. To the surgeon, only the genitourinary tract, major vascular structures, and sympathetic chain are generally considered to be retroperitoneal because of the way in which these structures are approached. The pancreas, also a retroperitoneal organ, has been discussed in previous chapters (Chapters 84 to 87).

The general approach to structures in this region involves mobilizing portions of overlying gastrointestinal tract by returning them to their original midline (embryonic) location. The complex anatomy of the underlying structures is first described by presenting the genitourinary tract. Chapters 105 and 106 des/cribe the anatomy of the adrenal (suprarenal) glands through a discussion of adrenalectomy, performed by (open) anterior and posterior approaches and laparoscopically. Chapter 105 also presents some anatomy of the back muscles in the section on the posterior approach to the adrenals. Renal anatomy is then described through a discussion of renal trauma, radical nephrectomy, and renal transplantation (Chapters 107 to 110e).