Asplenia
Asplenia is the condition characterized by the absence of a functioning spleen, which can occur either anatomically, where the spleen is completely missing, or functionally, where the spleen is present but not operational. The spleen, located in the upper left abdomen, plays a crucial role in the immune system, helping to filter blood and produce antibodies through its white pulp, while its red pulp is responsible for filtering out old or damaged blood cells. Individuals may be born without a spleen due to genetic conditions, or it may be removed surgically following trauma or disease.
The absence of a spleen significantly increases a person's risk of infections, particularly from bacteria, making vaccinations such as those for pneumococcal disease and meningitis essential for prevention. While adults who lose their spleen tend to cope better than children born without one, both groups require ongoing medical attention and education about recognizing early signs of illness. Preventive antibiotics are often prescribed to help mitigate the risks associated with asplenia. Overall, while asplenia poses challenges, with proper management, individuals can lead healthy lives.
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Subject Terms
Asplenia
- ANATOMY OR SYSTEM AFFECTED: Abdomen, immune system, spleen
Definition
Asplenia is the absence of a working spleen. The spleen is located in the upper left side of the abdomen and is roughly the size of a person’s fist. Asplenia can be anatomical, meaning the spleen is actually missing, or functional, in which the spleen is present but not functioning.
Although originally considered a nonessential organ, the spleen is now recognized as a vital part of the immune system. It is also part of the body’s system that manages waste material. The spleen has two different tissue types: white pulp and red pulp. White pulp makes white blood cells that, in turn, produce antibodies (infection-fighting proteins). Red pulp filters foreign or abnormal materials from the blood. It also destroys old or abnormal red blood cells.
Causes
Some people are born without a spleen. This can be part of a genetic condition that also causes problems with other organs (usually the heart). Sometimes only the spleen is missing and other organs are functioning properly. This can happen if, for example, the artery leading to the spleen does not develop normally in the fetus.
Sometimes the spleen has to be removed when it is damaged. Because the spleen stores blood cells, any injury to the spleen can cause severe, uncontrolled bleeding. Doctors commonly used to remove the spleen after such injuries, but this practice changed once the importance of the spleen to the immune system became clear.
The spleen also can stop working as a result of a disease that damages it. Sickle cell anemia, for instance, causes red blood cells to have an abnormal shape. This abnormal shape blocks the blood flow to the spleen and can cause irreparable damage.
Infection Risks
Because the spleen plays an important role in immunity, the absence of a spleen makes a person vulnerable to infections such as bacterial pneumonia and bacterial meningitis. Younger persons are more at risk for overwhelming, fatal infection in the absence of a spleen.
The heightened risk of infections can be somewhat alleviated by making sure persons without a functioning spleen receive several important vaccines: pneumococcal vaccine (which protects against several types of bacterial pneumonia), meningitis vaccine, hepatitis A and B vaccines, influenza vaccine, and Haemophilus influenzae type B (Hib) vaccine. (Hib does not cause the flu, despite its name. It is a bacterium that causes several types of dangerous infections throughout the body).
Impact
The absence of a spleen is manageable, but caution and education are required to prevent potential life-threatening complications. Persons without a spleen are often treated with preventive antibiotics for long periods of time, and they require specific vaccinations. These vaccinations include the pneumococcal vaccine, as well as the influenza vaccine, the coronavirus vaccine, and the meningococcal vaccines. Adults who lose their spleen do better than children born without one, but in either case, patients or their caregivers should be taught to watch for early signs of illness and should seek any needed medical attention sooner rather than later, so that infections do not flare out of control.
Bibliography
"Children and Adults Without a Fully Working Spleen (Asplenia)." NHS Inform, 20 Aug. 2024, www.nhsinform.scot/healthy-living/immunisation/when-to-immunise/children-and-adults-without-a-fully-working-spleen-asplenia/. Accessed 3 Feb. 2025.
DeFranco, Anthony, Richard Locksley, and Miranda Robertson. Immunity: The Immune Response in Infectious and Inflammatory Disease. Sunderland, Mass.: Sinauer, 2007.
Geha, Raif, and Fred Rosen. “Congenital Asplenia.” In Case Studies in Immunology. Hoboken, N.J.: Taylor & Francis, 2010.
Lichtman, Marshall A., et al., eds. Williams Hematology. 7th ed. New York: McGraw-Hill, 2006.