The detailed anatomy of the muscles and fascial layers of the anterior abdominal wall is described in Chapters 42 to 46. Peritoneal lavage is the first procedure illustrated in this section because it is often the first “laparotomy” performed by the junior resident or student. The general topography of the abdominal cavity is introduced in Chapter 42. The relationships of the viscera and a method for systematic exploration of the abdominal cavity, with considerations for trauma laparotomy, are described in Chapters 44 to 46. Additional information on the lateral abdominal wall may be found in chapters on specific procedures, such as appendectomy (Chapter 94), in which special abdominal incisions are described.