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Complete Blood Count (CBC)

Classically, the complete blood count (CBC) included hemoglobin, hematocrit, red blood cell (RBC) count, white blood cell (WBC) count, RBC indices, platelet count, and red cell distribution width (RDW).Today, automated cell counters can determine 32 different hematological parameters. These analyzers also incorporate a method for flagging white blood cell (WBC), red blood cell (RBC) and platelet abnormalities. The flagged abnormalities will prompt a manual peripheral smear review and differential by a clinical laboratory scientist to verify the abnormality flagged as well as allow identification of additional morphological abnormalities.Examples include:

WBC Abnormalities

  • Abnormal lymphocytes/lymphoblasts
  • Atypical lymphocytes
  • Basophilia
  • Blasts
  • Eosinophilia
  • Immature granulocytes
  • Left shift
  • Leukocytopenia
  • Leukocytosis
  • Lymphopenia
  • Monocytosis
  • Neutropenia
  • Neutrophilia
  • Nucleated red blood cell abnormal scatter
  • WBC abnormal scatter

RBC Abnormalities

  • Fragments (schistocytes)

Platelet Abnormalities

  • Platelet abnormal scattergram
  • Platelet clumps
  • Thrombocytopenia
  • Thrombocytosis

If specimens are flagged for review, the following RBC morphological abnormalities, if present, are reported by a clinical laboratory scientist: polychromasia, acanthocytes (spur cells), ovalocytes (elliptocytes), spherocytes, sickle cells (drepanocytes), target cells (codocytes), schistocytes, stomatocytes, rouleaux and basophilic stippling. RBC inclusions (Howell Jolly bodies), granulocyte abnormalities (toxic granulation, Dohle bodies, Pelger Huet, hypersegmented polymorphonuclear leukocytes) and giant platelets are also reported if present.

Slides with newly identified blasts, prolymphocytes, plasma cells or unusual WBC and RBC morphology are submitted by the clinical laboratory scientist to a pathologist for review. In addition, healthcare providers may order a pathologist review of a peripheral blood smear equisition form if they feel further morphological review is warranted.In these cases, the indication for the pathologist review should be clearly stated on the requisition form.

The reference ranges and critical values of the complete blood count are:


Reference Range

Critical Value


4,000 - 11,000/uL


>50,000/uL (if first diagnosis)

>100,000/uL (known patient)


Males 4.31 - 5.84 mil/uL

Females 4.00 - 5.00 mil/uL


Males 13.0 - 17.0 g/dL

Females 12.0 - 15. 0 g/dL

<6.0 g/dL


Males 40 - 50%

Females 36 - 45%


>70% neonates up to 2 mos

>60% all others


80 - 99 fL


27 - 34 pg


32 - 36%


0.4 – 1.8%

Immature Reticulocyte Fraction

0.0 – 0.16



Platelet Count

140,000 - 400,000/uL


>1 million/uL

Mean Platelet Volume

9.4 – 12.3 fL

Immature Platelet Fraction

1.1 – 7.1%

Reference range for the WBC differential count is:

White Cell




0 - 14%



45 - 78%

1.7 - 6.8 th/uL


15 - 47%

1.0 - 3.3 th/uL


0 - 12%

0.2 -0.9 th/uL


0 - 7%

0.0 - 0.4 th/uL


0 - 2%

0.0 - 0.2 th/uL

Specimen requirement is one lavender top (EDTA) tube.

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