Condensed Case

A 47-year-old man on a surgical floor was having daily CBCs ordered. A sample was received at 8 a.m. in the morning with the morning draw specimen. The results were delta checked and reported to the floor. Later in the day, the technologist received another sample for the same patient at 2 p.m. The results on this sample were vastly different and failed the delta check. On a hunch, the technologist retrieved the sample from the a.m. draw and took both samples to the blood bank for an ABO type. The ABO on the morning sample was type O; the ABO on the 2 p.m. sample was type A. The patient has a history of receiving O blood from the blood bank. What is the next course of action?

Answer

Proper patient identification is essential for accurate test results in the clinical laboratory. Extreme care must be taken by everyone involved in drawing and labeling a specimen to be analyzed. Samples may be drawn by the nursing staff, the physician, the infusion team, and the phlebotomist. Each of these individuals must never allow distractions or interruptions to interfere with the essential job of patient identification. In this case, the technologist called up to the surgical floor, explained the situation, and determined that the 2 p.m. sample had been mislabeled. The results on the afternoon sample were voided.

Summary Points

• Hematopoiesis is defined as the production, development, and maturation of all blood cells.

• Erythropoiesis in the fetus takes place in the yolk sac, spleen, and liver.

• Erythropoiesis in the adult takes place primarily in the bone marrow.

• Hematopoiesis within the bone marrow is termed intramedullary hematopoiesis; outside the bone marrow, it is termed extramedullary hematopoiesis.

• The bone marrow is one of the largest nonsolid organs of the body.

• The M:E ratio (3 to 4:1) reflects the amount of myeloid elements in the bone marrow compared with the erythroid elements in the bone marrow.

• Multipotential stem cells are capable of differentiating into nonlymphoid or lymphoid precursor committed cells.

28 Part I • Basic Hematology Principles

• EPO is a hormone produced by the kidneys that regulates erythroid production.

• A bone marrow aspirate and biopsy are invasive procedures usually performed at the location of the iliac crest in adults.

• The CBC consists of nine parameters: WBC, RBC, Hgb, Hct, MCV, MCH, MCHC, RDW, and platelet count.

• The MCV is one of the most stable CBC parameters over time.

• Increases in MCV can occur as a result of transfusion, reticulocytosis, hyperglycemia, and methotrexate.

• The RDW may be an early indicator of an anemic process.

• Critical values are those that are outside the reference range and that need to be immediately reported and acted on.

• The reticulocyte count is the most effective means of assessing red cell regeneration in response to anemic stress.

• Red cell production is effective when the bone marrow responds to anemic stress by producing an increased number of reticulocytes and nucleated red cells.

• Ineffective red cell production is described as death of red cell precursors in the bone marrow before they can be delivered to the peripheral circulation.

• Morphological classification of anemias is determined by the red cell indices.

• Microcytic, hypochromic anemias are characterized by an MCV of less than 80 fL and an MCHC of less than 32%.

• Macrocytic, normochromic anemias are characterized by an MCV of greater than 100 fL.

• Normocytic, normochromic anemias are characterized by an MCV between 80 and 100 fL and an MCHC of 32% to 36%.

• Normal red cells are disk-shaped flexible sacs filled with Hgb and having a size of 6 to 8 pm.

A 50-year-old woman was referred to a hematologist for recurring pancytopenia. At present, her WBC was 2.5 X 109/L; RBC, 3.0 X 1012/L; Hct, 30%; platelet count, 40 X 109/L; MCV, 68 fL; MCH, 26 pg; and MCHC, 36.5%. In addition to pancytopenia, she has been experiencing shortness of breath and fatigue for the past 3 weeks, and lately these symptoms had gotten worse. Her family history was unremarkable, but she explained that she has had excessive menstrual bleeding for the past 4 months. A CBC and differential were ordered, as well as a bone marrow examination. What is the likely cause for this patient's pancytopenia?

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