If your doctor thinks you might have leukemia, you will have a special kind of biopsy. For it, your doctor needs a small sample of bone marrow and bone. The doctor takes these from the inside of your pelvic bone. The procedure is called a bone marrow aspiration and biopsy. In some cases, the doctor takes an aspiration from the breastbone instead. A pathologist looks at the sample under a microscope. It may take a few days for the results to come back. Then your doctor knows if you have leukemia.