Spherocytes

Red cells which lose membrane become spherical, and can be recognized in the peripheral blood by their darker colour, and their lack of a central area of pallor. The two main causes are hereditary spherocytosis (in which the membrane structure is abnormal) and autoimmune hemolysis (in which the autoantibody attack creates abnormal membrane). In both cases, the red cells lose membrane in the reticuloendothelial system. The Direct Coombs' Test will distinguish between these two conditions, being positive in autoimmune hemolysis and negative in hereditary spherocytosis.