Chapter 481 Hyposplenism, Splenic Trauma, and Splenectomy

Hyposplenism

Congenital absence of the spleen is associated with complex cyanotic heart defects, dextrocardia, bilateral trilobed lungs, and heterotopic abdominal organs (Ivemark syndrome; Chapter 425.11). Splenic function is usually normal in children with congenital polysplenia. Functional hyposplenism may occur in normal neonates, especially premature infants. Children with sickle cell hemoglobinopathies (Chapter 456.1) may have splenic hypofunction as early as 6 mo of age. Initially, this is caused by vascular obstruction, which can be reversed with red blood cell (RBC) transfusion or hydroxyurea. The spleen eventually autoinfarcts and becomes fibrotic and permanently nonfunctioning. Functional hyposplenism may also occur in malaria (Chapter 280), after irradiation to the left upper quadrant, and when the reticuloendothelial function of the spleen is overwhelmed (as in severe hemolytic anemia or metabolic storage disease). Splenic hypofunction has been reported occasionally in patients with vasculitis, nephritis, inflammatory bowel disease, celiac disease, Pearson syndrome, Fanconi anemia, and graft vs host disease.

Splenic hypofunction is characterized by RBC inclusions in peripheral blood smears (Howell-Jolly bodies or Heinz bodies), “pits” on interference microscopy, and poor uptake of technetium on spleen scan. Patients with functional hyposplenism or asplenia are at increased risk for sepsis from encapsulated bacteria.