What is diagnostic pathology mean when on your medical bill?

"Diagnostic pathology" is a term used to describe a wide assortment of tests. In general, it refers to looking at tissues collected from your body under a microscope in order to diagnose or rule out disease or as doctors call it, "pathology". In this sense, it might be used to describe looking at the cells of the cervix after a Pap smear to check for evidence of cancer or infection. It might also be used to describe looking at a sample of skin tissue collected on a biopsy to check for evidence of skin cancer. There are many different uses for "diagnostic pathology"; these are only a couple.