Complete Blood Count, RBC Morphology and Inclusions

Complete Blood Count, RBC Morphology and Inclusions

Synonym/acronym: N/A.

Common use

To make a visual evaluation of the red cell shape and/or size as a confirmation in assisting to diagnose and monitor disease progression.


Whole blood from one full lavender-top (EDTA) tube or Wright’s-stained, thin-film peripheral blood smear. The laboratory should be consulted as to the necessity of thick-film smears for the evaluation of malarial inclusions.

Normal findings

(Method: Microscopic, manual review of stained blood smear)
Red Blood Cell MorphologyWithin Normal Limits1+2+3+4+
Anisocytosis0–55–1010–2020–50Greater than 50
Macrocytes0–55–1010–2020–50Greater than 50
Microcytes0–55–1010–2020–50Greater than 50
Poikilocytes0–23–1010–2020–50Greater than 50
Burr cells0–23–1010–2020–50Greater than 50
AcanthocytesLess than 12–55–1010–20Greater than 20
SchistocytesLess than 12–55–1010–20Greater than 20
Dacryocytes (teardrop cells)0–22–55–1020–50Greater than 20
Codocytes (target cells)0–22–1010–2020–50Greater than 50
Spherocytes0–22–1010–2020–50Greater than 50
Ovalocytes0–22–1010–2020–50Greater than 50
Stomatocytes0–22–1010–2020–50Greater than 50
Drepanocytes (sickle cells)AbsentReported as present or absent
Helmet cellsAbsentReported as present or absent
AgglutinationAbsentReported as present or absent
RouleauxAbsentReported as present or absent
Hemoglobin (Hgb) Content
Hypochromia0–23–1010–5050–75Greater than 75
AdultLess than 12–55–1010–20Greater than 20
Newborn1–67–1515–2020–50Greater than 50
Cabot ringsAbsentReported as present or absent
Basophilic stippling0–11–55–1010–20Greater than 20
Howell-Jolly bodiesAbsent1–23–55–10Greater than 10
Heinz bodiesAbsentReported as present or absent
Hgb C crystalsAbsentReported as present or absent
Pappenheimer bodiesAbsentReported as present or absent
Intracellular parasites (e.g., Plasmodium,Babesia,Trypanosoma)AbsentReported as present or absent


The decision to manually review a peripheral blood smear for abnormalities in red blood cell (RBC) shape or size is made on the basis of criteria established by the reporting laboratory. Cues in the results of the complete blood count (CBC) will point to specific abnormalities that can be confirmed visually by microscopic review of the sample on a stained blood smear.

This procedure is contraindicated for



  • Assist in the diagnosis of anemia
  • Detect a hematological disorder, neoplasm, or immunological abnormality
  • Determine the presence of a hereditary hematological abnormality
  • Monitor the effects of physical or emotional stress on the patient
  • Monitor the progression of nonhematological disorders, such as chronic obstructive pulmonary disease, malabsorption syndromes, cancer, and renal disease
  • Monitor the response to drugs or chemotherapy, and evaluate undesired reactions to drugs that may cause blood dyscrasias
  • Provide screening as part of a CBC in a general physical examination, especially upon admission to a health-care facility or before surgery

Potential diagnosis

Red Blood Cell Size

Increased in

    Cell Size

  • Alcoholism
  • Aplastic anemia
  • Chemotherapy
  • Chronic hemolytic anemia
  • Grossly elevated glucose (hyperosmotic)
  • Hemolytic disease of the newborn
  • Hypothyroidism
  • Leukemia
  • Lymphoma
  • Metastatic carcinoma
  • Myelofibrosis
  • Myeloma
  • Refractory anemia
  • Sideroblastic anemia
  • Vitamin B12/folate deficiency (related to impaired DNA synthesis and delayed cell division, which permits the cells to grow for a longer period than normal)

Decreased in

    Cell Size

    Hemoglobin C disease Hemolytic anemias Hereditary spherocytosis Inflammation Iron-deficiency anemia Thalassemias

    Red Blood Cell Shape

    Variations in cell shape are the result of hereditary conditions such as elliptocytosis, sickle cell anemia, spherocytosis, thalassemias, or hemoglobinopathies (e.g., hemoglobin C disease). Irregularities in cell shape can also result from acquired conditions, such as physical/mechanical cellular trauma, exposure to chemicals, or reactions to medications.

    Acquired spherocytosis can result from Heinz body hemolytic anemia, microangiopathic hemolytic anemia, secondary isoimmunohemolytic anemia, and transfusion of old banked blood. Acanthocytes are associated with acquired conditions such as alcoholic cirrhosis with hemolytic anemia, disorders of lipid metabolism, hepatitis of newborns, malabsorptive diseases, metastatic liver disease, the postsplenectomy period, and pyruvate kinase deficiency. Burr cells are commonly seen in acquired renal insufficiency, burns, cardiac valve disease, disseminated intravascular coagulation (DIC), hypertension, intravenous fibrin deposition, metastatic malignancy, normal neonatal period, and uremia. Codocytes are seen in hemoglobinopathies, iron-deficiency anemia, obstructive liver disease, and the postsplenectomy period. Dacryocytes are most commonly associated with metastases to the bone marrow, myelofibrosis, myeloid metaplasia, pernicious anemia, and tuberculosis. Schistocytes are seen in burns, cardiac valve disease, DIC, glomerulonephritis, hemolytic anemia, microangiopathic hemolytic anemia, renal graft rejection, thrombotic thrombocytopenic purpura, uremia, and vasculitis.

    Red Blood Cell Hemoglobin Content

    RBCs with a normal hemoglobin (Hgb) level have a clear central pallor and are referred to asnormochromic. Cells with low Hgb and lacking in central pallor are referred to as hypochromic. Hypochromia is associated with iron-deficiency anemia, thalassemias, and sideroblastic anemia. Cells with excessive Hgb levels are referred to as hyperchromic even though they technically lack a central pallor. Hyperchromia is usually associated with an elevated mean corpuscular Hgb concentration as well as hemolytic anemias. Cells referred to as polychromic are young erythrocytes that still contain ribonucleic acid (RNA). The RNA is picked up by the Wright’s stain. Polychromasia is indicative of premature release of RBCs from bone marrow secondary to increased erythropoietin stimulation.

    Red Blood Cell Inclusions

    RBC inclusions can result from certain types of anemia, abnormal Hgb precipitation, or parasitic infection.

    Cabot rings may be seen in megaloblastic and other anemias, lead poisoning, and conditions in which RBCs are destroyed before they are released from bone marrow. Basophilic stippling is seen whenever there is altered Hgb synthesis, as in thalassemias, megaloblastic anemias, alcoholism, and lead or arsenic intoxication. Howell-Jolly bodies are seen in sickle cell anemia, other hemolytic anemias, megaloblastic anemia, congenital absence of the spleen, and the postsplenectomy period. Pappenheimer bodies may be seen in cases of sideroblastic anemia, thalassemias, refractory anemia, dyserythropoietic anemias, hemosiderosis, and hemochromatosis. Heinz bodies are most often seen in the blood of patients who have ingested drugs known to induce the formation of these inclusion bodies. They are also seen in patients with hereditary glucose-6-phosphate dehydrogenase (G6PD) deficiency. Hgb C crystals can often be identified in stained peripheral smears of patients with hereditary hemoglobin C disease. Parasites such as Plasmodium (transmitted by mosquitoes and causing malaria) and Babesia (transmitted by ticks), known to invade human RBCs, can be visualized with Wright’s stain and other special stains of the peripheral blood.

Critical findings

  • The presence of sickle cells or parasitic inclusions should be brought to the immediate attention of the requesting HCP.

  • It is essential that a critical finding be communicated immediately to the requesting health-care provider (HCP). A listing of these findings varies among facilities.

  • Timely notification of a critical finding for lab or diagnostic studies is a role expectation of the professional nurse. Notification processes will vary among facilities. Upon receipt of the critical value the information should be read back to the caller to verify accuracy. Most policies require immediate notification of the primary HCP, Hospitalist, or on-call HCP. Reported information includes the patient’s name, unique identifiers, critical value, name of the person giving the report, and name of the person receiving the report. Documentation of notification should be made in the medical record with the name of the HCP notified, time and date of notification, and any orders received. Any delay in a timely report of a critical finding may require completion of a notification form with review by Risk Management.

Interfering factors

  • Drugs and substances that may increase Heinz body formation as an initial precursor to significant hemolysis include acetanilid, acetylsalicylic acid, aminopyrine, antimalarials, antipyretics, furaltadone, furazolidone, methylene blue, naphthalene, and nitrofurans.
  • The results of a complete blood count (CBC) should be carefully evaluated during transfusion or acute blood loss because the body is not in a state of homeostasis and values may be misleading. Considerations for draw times after transfusion include the type of product, the amount of product transfused, and the patient’s clinical situation. Generally, specimens collected an hour after transfusion will provide an acceptable reflection of the effects of the transfused product. Measurements taken during a massive transfusion are an exception, providing essential guidance for therapeutic decisions during critical care.
  • Leaving the tourniquet in place for longer than 60 sec can falsely affect the results.
  • Morphology can be evaluated to some extent via indices; therefore, failure to fill the tube sufficiently (i.e., tube less than three-quarters full) may yield inadequate sample volume for automated analyzers and may be a reason for specimen rejection.
  • Hemolyzed or clotted specimens should be rejected.

Nursing Implications and Procedure


  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this test can assist in assessing red cell appearance.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s gastrointestinal, hematopoietic, hepatobiliary, immune, and respiratory systems; symptoms; and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Note any recent procedures that can interfere with test results.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Note that there are no food, fluid, or medication restrictions unless by medical direction.


  • Potential complications: N/A
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture. An EDTA Microtainer sample may be obtained from infants, children, and adults for whom venipuncture may not be feasible. The specimen should be mixed gently by inverting the tube 10 times. The specimen should be analyzed within 6 hr when stored at room temperature or within 24 hr if stored at refrigerated temperature. if it is anticipated the specimen will not be analyzed within 4 to 6 hr, two blood smears should be made immediately after the venipuncture and submitted with the blood sample. Smears made from specimens older than 6 hr will contain an unacceptable number of misleading artifactual abnormalities of the RBCs, such as echinocytes and spherocytes, as well as necrobiotic white blood cells.
  • Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
  • Promptly transport the specimen to the laboratory for processing and analysis.


  • Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
  • Nutritional Considerations: Instruct patients to consume a variety of foods within the basic food groups, maintain a healthy weight, be physically active, limit salt intake, limit alcohol intake, and avoid the use of tobacco.
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include biopsy bone marrow, CBC, CBC hematocrit, CBC hemoglobin, CBC platelet count, CBC RBC count, CBC RBC indices, CBC WBC count with differential, δ-aminolevulinic acid, erythropoietin, ferritin, G6PD, hemoglobin electrophoresis, iron/TIBC, lead, and reticulocyte count.
  • Refer to the Gastrointestinal, Hematopoietic, Hepatobiliary, Immune, and Respiratory systems tables at the end of the book for related tests by body system.
Handbook of Laboratory and Diagnostic Tests, © 2013 Farlex and Partners
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