The Function of the Spleen

The spleen is one of the least understood organs of the human body. Unlike organs that are noticed every day, such as the skin, most people never think about the spleen unless it becomes damaged by trauma.

While the spleen is not as well known as other organs, it performs multiple important functions. The spleen participates in the creation of blood cells and also helps to filter out the blood, removing old blood cells and fighting infection. The spleen also helps to control the amount of blood circulating through the body by creating a reserve pool of blood that can be released during severe bleeding to help improve circulation, oxygenation and blood pressure in dire circumstances. 

The spleen is rarely the cause of health issues so it is often overlooked when talking about wellness and prevention of illness. The spleen does contribute to overall good health, but it is also not an essential organ, which is important because it can be fragile and may need to be surgically removed. 

A doctor checking a patients spleen
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The Spleen Is a Helper, Not Essential

The spleen works with other organs in the body to complete the tasks of blood storage, fighting infection and filtering the blood. While the spleen is useful and does perform vital tasks, other organs in the body also work to filter the blood and fight infection, and blood cells are mainly produced in the bones.

It is this overlap in duties makes it possible for the spleen to be removed without causing lasting harm to the individual. While most people are somewhat healthier with a spleen, it is absolutely possible to have a normal life without a spleen. So the spleen is important but it isn’t essential.

The Fragile Spleen

The spleen holds reserve blood in case of significant bleeding, much like a blood-filled balloon, and acts as a reserve source of extra blood. In a trauma situation, particularly a severe car crash where an individual is wearing a seat belt, the force of impact can actually cause the spleen to rupture and begin to hemorrhage blood. The spleen has a high amount of blood flow, which can lead to a tremendous amount of bleeding when there is a serious injury and the bleeding can quickly become life-threatening. In some cases, when there is no other option, a splenectomy, the surgical procedure to remove the spleen, is performed.

The spleen can also become enlarged, stretching over time, until it becomes unable to function. It can expand over time from normal size (which is approximately the size of a small chicken breast) to the size of a softball or approaching the size of a volleyball. As a spleen becomes enlarged, it becomes more fragile and is more likely to be damaged in an accident.

Living Without a Spleen

As the spleen is not the only organ responsible for any of these functions, the spleen is not a necessary organ. It is possible to have the spleen removed and live a healthy life. Individuals without a spleen may be more likely to contract some types of infections as the body will have fewer B cells, the cells that “remember” exposure to bacteria and “remember” how to fight them.

The risks of contracting an infection are highest in the first two years following surgery. Individuals who have had their spleen removed will need to tell healthcare providers that their spleen is absent, as they will always be at higher risk for infection. It is important that a person without a spleen not ignore early signs of infection, such as a fever, as the body is more likely to require antibiotics to fight infection effectively.

In general, a person without a spleen will go on to have a healthy life, but they will always have a greater risk of contracting pneumonia and vaccines will be less effective. Vaccines nonetheless are essential to prevent serious illness. Along with annual flu shots, talk to your healthcare provider about which other vaccines are especially important, such as vaccines to protect against pneumonia and meningitis.

A Word From Verywell

While the spleen is a well-known organ, it often becomes the cause of significant worry after a car accident or other incident that leads to bleeding. This might require removal of the spleen to stop blood loss. For people who have their spleens removed, aside from being advised to have more vaccines than other individuals might, the end of the recovery from surgery is the last time they are concerned about their spleen.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  4. Centers for Disease Control and Prevention. Asplenia and adult vaccination.