FMLA
I used FMLA when I had my surgery. I had to provide the ICD-9 code for the procedure, but did not have to explicitly tell them what surgery I was having. Medical information is supposed to stay private and management should not be able to disclose any of that information. Do you have an HR person you can go through?
I used FMLA for my surgery. I also was able to reapply when I had complications as long as my surgeon wrote in the application that it was specifically related to my original surgery. I still had to use my leave at work, but when the complication**** they had to use my extended leave first and not touch my annual leave. This was a big help.