A special blood test is used to diagnose primary myelofibrosis. In addition to a complete blood count, bone marrow aspiration and biopsy, and cytogenetic analysis, a peripheral blood smear is used to diagnose primary myelofibrosis. A peripheral blood smear is a procedure in which a sample of blood is checked for tear drop-shaped red blood cells, the number and kinds of white blood cells, the number of platelets, and the presence of blast cells.