What Organ Is Under the Ribs on the Left Side?

The spleen is located on the left side of the abdomen, under the ribcage and toward the back of the body. The primary function of the spleen is to filter the blood, recycle red blood cells, and store platelets along with white blood cells.

The spleen is part of the lymph system and is important for fighting bacterial infections. White blood cells are produced in the spleen and filter dead cells, bacteria and foreign bodies from the blood. The spleen varies in size by individual but is commonly the size of a fist. The organ is purple in color and is protected by the ribcage, making it difficult to feel unless it is enlarged. A spleen is not necessary for human survival, but a person is more prone to infections such as streptococcus, meningitis, pneumonia and certain types of influenza without it.