Chapter 10: The Spleen

Located under the left costal margin, this organ functions as a sophisticated filter with a unique open circulation system. In the red pulp, which comprises the majority of the splenic mass, specialized cords and sinuses monitor red blood cells, removing nuclear remnants and abnormal cells that have lost their flexibility. Parallel to this, the white pulp serves as a specialized lymphatic region, housing T-cell zones and B-cell follicles that recognize blood-borne antigens. The spleen is also capable of resuming blood cell production, known as extramedullary haemopoiesis, when the bone marrow is compromised by disease. Clinical assessment often involves imaging techniques like ultrasound or CT scans to evaluate size and structure. Splenomegaly, or splenic enlargement, arises from various triggers, including haematological malignancies like chronic myeloid leukaemia, portal hypertension, and tropical infections such as malaria. When the spleen becomes overactive, a condition called hypersplenism may occur, leading to the excessive pooling of platelets and other blood cells, which causes peripheral cytopenias despite healthy marrow function. Conversely, hyposplenism or the surgical removal of the spleen leaves individuals highly vulnerable to life-threatening infections from encapsulated bacteria. Managing these risks requires lifelong antibiotic prophylaxis and a rigorous vaccination schedule against specific pathogens like Streptococcus pneumoniae. Post-operative care following a splenectomy must also account for potential spikes in platelet counts and associated clotting risks, emphasizing the spleen's critical involvement in maintaining systemic haematological balance.