Spherocytes are red blood cells that are sphere-shaped rather than the usual round doughnut shape. Spherocytes are more fragile than normal red cells and their presence is accompanied by anemias of varying severity.
Hereditary spherocytosis is the most common red blood cell membrane abnormality in the Caucasian (white) population. In hereditary spherocytosis, 5 to 20% of red blood cells are spherocytes. Spherocytes are also found in several forms of hemolytic anemia, including autoimmune hemolytic anemia (up to 100% spherocytes), hemolytic disease of the newborn (Rh incompatibility), infectious or drug-induced anemias, etc.