Final answer:
Megaloblastic anemia is characterized by the presence of enlarged immature red blood cells, known as macrocytes, and may include hypersegmented neutrophils. A blood smear reveals these macrocytes along with other abnormalities such as anisocytosis and poikilocytosis, with a typically elevated mean corpuscle volume (MCV) indicating macrocytic anemia.
Step-by-step explanation:
The peripheral blood morphology of megaloblastic anemia is characterized by the presence of large, immature red blood cells (RBCs) called macrocytes. These cells are typically larger than normal due to faulty or decreased RBC production, often resulting from deficiencies in vitamin B12 or folate. In a blood smear, macrocytes appear as large, oval cells with a lighter staining area in the center. Often associated with these macrocytes are hypersegmented neutrophils, which have more than the usual number of nuclear lobes, typically five or more.
Other features present in a megaloblastic anemia smear might include anisocytosis, which is the presence of RBCs of varying sizes, and poikilocytosis, the presence of abnormally shaped red blood cells. These morphological abnormalities can result in reduced levels of oxygen delivery to body tissues, manifesting as fatigue, lethargy, an increased risk for infection, and other symptoms. The mean corpuscle volume (MCV) in these patients is elevated, often indicating that the anemia falls into the category of macrocytic anemias. A lower reticulocyte count may also be indicative of inadequate RBC production.