Assessments of stained smears are performed if
results meet specific numeric and/or instrument flagging criteria. Smear
review includes assessment of WBC cell populations, presence of WBC
and/or RBC inclusions, RBC morphology, and platelet evaluation.
Presence
of one or more of the following may be indication for further
investigation: hemoglobin <10 g/dL, hemoglobin >18 g/dL, MCV
>100 fL, MCV <80 fL, MCHC >37%, WBC >20,000/mm3, WBC <2000/mm3,
presence of sickle cells, spherocytes, Pappenheimer bodies, basophilic
stippling, stomatocytes, schistocytes (fragmented RBCs), target cells,
oval macrocytes, teardrop red blood cells, abnormal cell populations,
nucleated red blood cells in other than the newborn, blood parasites
(malarial or Babesia organisms or the possibility of parasitic
organisms), hypersegmented neutrophils, agranular neutrophils,
hyposegmented neutrophils (Pelger-Huët anomaly or pseudo-Pelger-Huët
[pelgeroid] cells), mononuclear cells in which apparent nucleoli are
prominent (blast-like cells), presence of metamyelocytes, myelocytes,
promyelocytes, neutropenia, presence of plasma cells, peculiar atypical
lymphocytes, significant increase or decrease in platelets or bizarre
platelets.
A six-part differential reported in some lab locations
includes IG % and IG absolute counts. IG (immature granulocytes)
includes metamyelocytes and myelocytes. It does not include bands or
blast cells.1,2 Promyelocytes and blasts are reported
separately to denote the degree of left shift. An elevated percentage of
IG has not been found to be clinically significant as a sole clinical
predictor of disease. IGs are associated with infections, a variety of
inflammatory disorders, cytokine therapy, neoplasia, hemolysis, tissue
damage, seizures, metabolic abnormalities, myeloproliferative neoplasms,
and with the use of certain medications such as steroids.3
Pregnancy-associated
leukocytosis may also show increased immature granulocytes without
clinical significance. There is a significant increase of normoblastic
erythropoiesis and, to a lesser extent, of granulopoiesis during
pregnancy, which is associated with an increase in immature cells (shift
to the left) of both erythropoietic and granulopoietic tissues. A
possible physiologic explanation for the appearance of immature
granulocytes in the peripheral blood of pregnant women, increased
alkaline phosphate activity in granulocytes, and increased glycogen
content of lymphocytes may be found in the excretion curves of hormones
during pregnancy. There is a sharp rise in the fifth month then a
decrease in the eighth month and a subsequent rise in the ninth month.4