Abnormal results of studies such as a complete blood count (CBC) and WBC count and differential indicate the need to determine the individual's hematopoietic function. Evaluation of hematopoiesis begins with the examination of a bone marrow sample and may subsequently require other studies and a sample of peripheral blood, either venous or capillary.
Although the collection of blood specimens is usually the responsibility of the laboratory technician or phlebotomist, it is often the responsibility of the nurse in emergency departments, critical care units, and community and home care settings. A detailed description of procedures for obtaining peripheral blood samples is provided in Appendix I.