Ultrasounds

I am taking Tamoxifen and also have a family history of uterine cancer.  For this reason both my oncologist and gyn thought a pelvic and transvaginal ultrasound was warranted.  I had the ultrasound done last October. 

A month ago, I just received a bill from my hospital for the ultrasound...10 months after the date of service.  I've been told by the insurance company that it was denied because the diagnosis code used was "routine".  The doctors office told me the code they used was for family history...not sure why that is routine.  The hospital says it took them so long to bill me because the insurance company at first put through an adjustment for the contracted amount (last October) so they assumed it was going to be paid.  Then, June 2010 the insurance company reversed that adjustment and said it had been denied.  Of course, the insurance company is telling me that I am past my 180 day period that I had to appeal because they started that clock running last October...however I had no idea during that 180 days that it had been denied because I was not billed. 

My question is just if anyone has had issues with insurance regarding pelvic/transvag ultrasounds?  I really just want to find out if the insurance company had all the facts to make their determination...I don't think "family history" is really the whole story here.  I don't know if knowing I am on Tamoxifen and that I have a personal history of breast cancer makes a difference?  When I call and try to explain this all I am told is that they denied based on the diagnosis code that was used.  And neither the hospital or my gyn's office are being at all helpful.  I was thinking my next step should be to write to BCBS and ask for copies of what they used to make their determination?  Would they have something that spells out what diagnosis codes are covered and which are not?

Thanks for any words of wisdom! 

Carolyn