Subperitoneal extension of disease processes between the chest, abdomen, and the pelvis.

The subserous space is a large, anatomically continuous potential space that interconnects the chest, abdomen, and pelvis. The subserous space is formed from areolar and adipose tissue, and contains branches of the vascular, lymphatic, and nervous systems. As such, it provides one large continuous space in which many disease processes can spread between the chest, abdomen, and the pelvis.