This report expands the concept of the subperitoneal space (SS) as the potential conduit for direct spread of disease in the abdomen to include the female pelvis. The normal anatomy of the SS in the lower abdomen, the female pelvis, and its uninterrupted continuation between the abdomen and pelvis are demonstrated by several imaging modalities. Surgically proven cases of bidirectional spread of disease between the abdomen and female pelvis are reported. The unifying concept of the interrelationship formed by the SS provides an understanding of the basic concepts of the pathways of direct spread of disease and the pathogenesis of the clinical presentation of disease distant from its site of origin.