The spleen filters blood, removes old red blood cells and platelets, stores blood, and plays an important role in the immune system. It lies in the left upper abdomen. The spleen can be damaged by trauma, which ranges from superficial bruising to complete rupture. Rupture presents with shock, abdominal pain, and swelling. Treatment is splenectomy for adults but splenic preservation is attempted for children. The spleen can also enlarge in diseases like portal hypertension, leading to a condition called hypersplenism with low blood counts.