Pelvic Extraperitoneal Spaces and Organ Origin of a Mass
Recognize prevesical, perivesical, pararectal, and presacral spaces, then establish the compartment and organ origin of a pelvic mass.
The differential diagnosis of a pelvic mass becomes shorter once its organ or extraperitoneal space of origin is established. Peritoneum, endopelvic fascia, bladder, rectum, and pelvic sidewalls constrain routes of spread. When a large mass distorts anatomy, its center, feeding vessels, and angles with adjacent organs are more useful than an early lesion name.
The extraperitoneal pelvis can be reviewed through the prevesical, perivesical, perirectal, pararectal, and presacral spaces. These are not sealed compartments. Infection, hemorrhage, and tumor can cross fascial pathways, so the report should name both the dominant center and extensions.