• Asplenia is the absence of the spleen due to either a congenital anomaly or a surgical procedure.
  • Hyposplenia is the reduced or absent function of the spleen, impairing the capacity to prevent bacterial infections.


  • The exact incidence is not known.
  • Asplenia is present in about 3% of neonates with structural heart disease.
  • Isolated asplenia is most often recognized at autopsy.


  • The spleen is a major component of the reticuloendothelial system; it is important both for antibody synthesis and for clearance of opsonized organisms by phagocytosis.
  • Antibody-mediated phagocytosis is the primary mechanism to destroy encapsulated microbes, such as pneumococcus, meningococcus, and Haemophilus.
  • In the absence of the spleen’s phagocytic pathway, the polysaccharide-rich capsules of these bacteria protect them from destruction and permit them to effect systemic bacterial infection that may lead to overwhelming sepsis.
  • For patients <4 years of age in whom few alternate routes of bacterial clearance exist, significant pathology can result from impaired splenic function.


  • Surgical splenectomy
  • Congenital asplenia
  • In association with certain diseases or conditions (see “Differential Diagnosis”)

Commonly Associated Conditions

  • Besides splenectomy, when asplenia is known, patients with certain diseases are at risk of asplenia or hyposplenia (see “Differential Diagnosis”).
  • Asplenia or hyposplenia should be suspected in any patient with overwhelming infection with an encapsulated organism.

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