Asplenia/Hyposplenia

Descriptive text is not available for this imageBASICS

DESCRIPTION

  • Asplenia is the complete loss of function of the spleen due to a surgical procedure, congenital anomaly, or functional loss caused by a medical condition.
  • Hyposplenia is the partial loss of function of the spleen, impairing the capacity to prevent bacterial infections.

EPIDEMIOLOGY

  • 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.

ETIOLOGY

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

PATHOPHYSIOLOGY

  • The spleen is a major component of the reticuloendothelial system; it is important for antibody synthesis, filtering of old and damaged red blood cells, as well as phagocytosis of opsonized bacteria.
  • Antibody-mediated phagocytosis is the primary mechanism to destroy encapsulated microbes, such as pneumococcus, meningococcus, and Haemophilus influenza.
  • 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.

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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