The spleen is an organ in the body that filters the blood by removing damaged blood cells and bacteria.

Sickled red blood cells may damage parts of the spleen, preventing it from working properly. When the spleen doesn't work properly, people with sickle cell disease are more likely to have serious, life-threatening infections with certain types of bacteria. In older children and adults, the spleen often disappears because of years of damage from sickled cells.