Difference in mammograms

I am scheduled to go for my yearly mammo tomorrow. But I noticed on the script that it said diagnostic and not screening and this has me puzzled. Every year I go for a screening and every year I get a call from the hospital telling me I have to go back for compression films and every year it's something different. Can you tell me the difference between screening and diagnostic and how is diagnostic different from compression films? I have 3 cysts on the left side, I have ADH, fibrocycstic breast disease and very dense breast tissue - so far I've had a mass, a nodule, and 3 cysts diagnosed. Is a diagnostic mammogram more practical in my situation and possibly save me from future compression films?

[CCF-RN,MSN-rf]

Dear jlady:  A screening mammogram is done routinely on women who have no known abnormalities and includes two views of the breast a top/bottom view and a side/side view.  If there is a history of breast abnormalities or new complaints, then a diagnostic mammogram will be ordered to focus in on the area of concern.  The diagnostic mammogram could include additional views as well as spot compression to further clarify the area of concern.  It may be reasonable to order a diagnostic mammogram in your case but it may be worth a discussion with
your doctor and/or your insurance company to be certain that this procedure will be covered if a screening mammogram is not done first.