Extra- peritoneal Endo

It sounds like it's the area outside of the pelvic cavity; so beyond the normal reproductive organs area.  I'm not a doctor, though, and don't really know the definition of extra peritoneal Endo...but extraperitoneal is the area outside the peritoneum (a membrane).  Endo is a tricky beast; even with a hysterectomy, it can return.  It may be that you still have some Endo implants within your body (it can grow anywhere...I have mine on my liver and diaphragm) like the lungs, heart lining, skin, bowel, bladder, etc.  If there are implants left inside, even after your hysterctomy, they can continue to grow and spread.   Did they take one or both of your ovaries?  It's been shown that estrogen feeds our disease...even if you don't have any ovaries, your body still creates estrogen.

If you can, keep seeking doctor opinions.  And fight for your own body.  I have several EndoSisters that are my personal friends that have had hysterectomies and continue to suffer with their Endo symptoms.  One woman has it inside of her spine...