This is obtained by inserting a hollow needle into the bone cavity (usually the iliac crest or sternum). A specimen, after decalcification, sectioning, and staining, is examined under low power microscopy. The staining characteristics, number and morphology of cells may be suggestive and sometimes diagnostic of certain blood related diseases. Material effects, risks and side effects: prolonged bleeding time if the patient has bleeding tendency, infection, the needle on the sternum may suddenly go through the bone and puncture the heart or large blood vessels.