- 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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