Poikilocytosis is a medical term that refers to the presence of abnormally shaped red blood cells in the bloodstream. Synonyms for poikilocytosis include anisocytosis, which describes red blood cells that are of uneven sizes, and macrocytosis, which refers to red blood cells that are larger than normal. Another synonym is microcytosis, which describes red blood cells that are smaller than normal. Hypochromasia is a term used to describe red blood cells that have decreased amounts of hemoglobin, leading to a paler coloration. Finally, schistocytosis refers to the presence of fragmented red blood cells, while elliptocytosis describes red blood cells with an oval or elliptical shape.