Presacral hematoma

Endometriosis is a condition in which cells similar to those in the endometrium, the layer of tissue that normally covers the inside of the uterus, grow outside the uterus. Most often this is on the ovaries, fallopian tubes, and tissue around the uterus and ovaries; however, in rare cases it may also occur in other parts of the body. [Source: Wikipedia ]

May Cause
Increased presacral space
May Be Caused by
Sacral fracture