Asplenism

Asplenism refers to the loss of spleen function, either due to surgical removal of the spleen (splenectomy) or due to loss of splenic phagocytic activity (but splenic tissue is intact). The latter is called functional asplenism, while the former is anatomic asplenism. Functional asplenism is usually preceded by hyposplenism.

Asplenism is important because losing splenic function means losing the body's protection against encapsulated bacteria, which can lead to severe infection.

Etiology

• Splenectomy (due to splenic rupture, ITP)
• Functional asplenism
  • Splenic infarctions
  • Autoimmune disease
  • Sickle cell disease
  • Thalassaemia

Pathomechanism

It's hypothesised that functional asplenism is caused by repeated splenic infarction or infiltration.

Evaluation

The presence of Howell-Jolly bodies on a blood smear indicates hyposplenism or asplenism. These bodies are remnants of old RBCs which are normally removed by the spleen.

Overwhelming post-splenectomy infection

Overwhelming post-splenectomy infection (OPSI) is a rare but life-threatening infection by encapsulated bacteria which occurs in asplenic patients. This may rapidly progress from mild viral-like symptoms to sepsis and death within hours. The mortality rate is approx. 50%.

To prevent OPSI, it’s important to vaccinate asplenic patients against encapsulated bacterial diseases, including haemophilus influenzae, meningococcus, and pneumococcus, preferably before they become asplenic. High risk patients may receive antibiotic prophylaxis.