Dear Cheryl4WD, Platelets having dropped so dramatically and not rebounded after discontinuing chemotherapy would need to be put into context of your entire situation. Many factors could influence platelet counts such as prior treatment, length of time on medication etc. Having the oncologist and/or the hematologist evaluate your situation completely makes sense. The bone marrow biopsy is done to see what is happening in terms of the blood producing cells in the body. By checking the bone marrow the hematologist is trying to find clues as to why your blood counts are not recovering as anticipated and not necessarily to see if the breast cancer has spread to the bones.