Those were just some examples of things that might lead to incomplete diagnosis.
The "bottom line" message of a BIRAD 0 is: "Your mammogram or ultrasound didn't give the radiologist enogh information to make a clear diagnosis; follow-up imaging is necessary.
I never had any breast surgeries.. What would cause scar tissue..
BIRADS 0 is described below. I would just wait for the follow-up visit and try not to jump to conclusions meanwhile (which of couse is easier said than done! :-< ).
"Category 0 -- Incomplete
Your mammogram or ultrasound didn't give the radiologist enough information to make a clear diagnosis. Don't worry, this may mean that scar tissue from a previous surgery or biopsy may have shown up, or that a lump that is big enough to be easily felt isn't imaging clearly. You will need to have a follow-up image done. "
(If you would like to see the rest of the BIRADS classification, I just listed it in my response to a post entitled "Zouzi" by alidi.)
Best wishes...