The spleen is an organ of the lymphatic system that is located in between the 9th and 12th thoracic ribs on the left side of the body. It is composed of masses of lymphoid tissue and twisted veins and fibers, and plays an important role in the immune system, constantly storing blood platelets and white blood cells. In an average adult up to 30% of blood platelets are stored away by the spleen. Your spleen also helps control the amount of blood in your body, and destroys old and damaged cells. Although once thought to have been a non-vital organ, the importance of this organ in immune defense is vital. However, due to many circumstances, the spleen may become enlarged and start to provide problems for the human body, but this is often solved by removal of the organ (splenectomy).
The spleen lies beneath the 9th and 12th thoracic ribs. It is approximately 11 centimeter in length and weighs between 150 to 200 grams. It is closely similar to a clenched fist. The spleen is encased in a capsule with a trabeculae skeleton, which extends into the spleen from the capsule. Although very similar to the structures of the lymph nodes, the spleen has smooth muscle tissue while the lymph nodes do not. Throughout the inside of the spleen there are two different types of tissue. The two different types are red pulp and white pulp. The white pulp is very similar to the lymph nodes, as it is composed of diffused lymphatic tissue and lymph nodes. In the spleen it is found in the arteries which enter the spleen. The red pulp is made up of twisted veins and reticular fibers. They are filled with blood cells which were in the capillaries of the spleen.
The spleen has three major functions. Although it is part of the lymphatic system it does not filter lymph, rather it filters the blood. As the blood passes through the spleen the white pulp of the spleen begin to stimulate a response to the foreign material that has been filtered through the blood. This aids in the production of antibodies to ward off bacteria,viruses, germs, and any other micro organism. As blood cells have a short life cycle they must be continually replaced with new cells. The second major function of the spleen is to clean out the blood. This is accomplished by the red pulp in the blood. As the blood passes through the red pulp, macrophages in the spleen engage in phagocytosis to remove the worn-out blood cells. In addition the macrophages also engulf foreign contaminants from the blood. Although this process removes a lot of substances from the blood, the nutrients that remain were process remain in the blood. One main component saved is iron, and it is stored in the spleen as bilirubin and ferritin. Once needed the iron is then transported from the spleen to the bone marrow, where new blood cells are made. The third major function of the spleen is to be a reservoir for extra blood. Since this blood is highly oxygenated it is used as a backup blood supply in case of blood loss.  When the body detects blood loss, the autonomic nervous system begins to work. More specifically the sympathetic division of the ANS stimulates the smooth muscle found in the capsule of the spleen to contract, allowing the blood to be pushed back up into the blood stream to compensate for the loss of blood. The benefit of this function can more specifically be seen in the animal. For example the seal uses this extra blood supply in their spleens as an oxygen tank for when they can not surface and they have a low amount of oxygen, allowing them to stay under the water for a longer amount of time. 
Certain diseases might cause your spleen to swell. You can also damage or rupture your spleen in an injury, especially if it is already swollen. If your spleen is too damaged, you might need surgery to remove it. You can live without a spleen. Other organs, such as your liver, will take over some of the spleen's work. Without a spleen, however, your body will lose some of its ability to fight infections.
Splenomegaly also called an enlarged spleen is not a disorder in itself, but rather an effect of an underlying problem. Since many things can lead to the condition, the cause can be very difficult to pinpoint exactly. The spleen enlarges due to hypersplenism (an excessive number of blood cells and platelets storage), overall affecting the number of blood cells and platelets found within the body. This trapping of the white blood cells and platelets begins to form a repetitive cycle. The spleen continues to grow in size. After the spleen has grown to a certain point it will begin to trap the normal red blood cells along with the abnormal blood cells, destroying them both. It only can continue to grow trapping more and more blood cells and platelets. This continually trapping of these particles will result in a clog in the spleen. When this clog happens it begins to reduce the overall function of the spleen. Although the spleen is located in a tight space, it continues to grow, outgrowing the structure were it is located. This excessive growth of the spleen begins to lead to an excessive blood draw. However, when this blood supply has not been met, it will cause parts of the spleen to go without blood, causing them to either bleed or die. 
Asplenia is a condition which the spleen does performs its function despite a person having either a normal or enlarged spleen. This condition is more specifically called functional asplenia. Although once a non-vital organ, the spleen is a secondary lymphoid organ in immune defense and as a filter for the blood. This condition is often found only after a person has had a demobilizing infection that has caused the investigation of the immune system. However, asplenia is often found in association with other anomalies. One of the most common of the anomalies is Ivemark syndrome. Ivemark syndrome is the condition where the right-sided organs are duplicated and the organs that are on the left side of the body are missing. This condition is often found in infants during the neonatal period. Other conditions which asplenia occurs in are Pearson syndrome (pancreatic insufficiency, sideroblastic anemia), Stormorken syndrome (thrombocytopenia and miosis), and Smith-Fineman-Myers syndrome (mental retardation). In addition it is said to cause diseases in the liver pancreas, and kidneys. 
Often due to the location of the spleen it faces a great deal of abuses. When a severe blows is given to the abdominal whether by sports, car accidents, beating, or other physical activity, the skin that covers the spleen can tear and cause massive bleeding in the abdominal area. One concern with this is due to the size of the cut that is found on the spleen. If the cut is not deep at all the wound will relatively quickly, but if the wound is deep, a hemorrhage can occur and cause compilations. However another concern is that blood with form under the skin of the spleen during the recovery period causing a hematoma. Although not physically deadly at first, it poses a serious risk. Although at first the spleen might seen fine, but after weeks to months after the incident has happened the spleen may rupture due to the hematoma. However, this time frame can vary diversely. To treat this there is two way, one is to remove the spleen by a splenectomy and the second is to allow the spleen to repair on its own or by minor help from a surgeon. 
Removal of the Spleen
The doctor may suggest removal of the spleen for a variety of reasons, some of which being:
- Infections: These infections can by viral, bacterial, or parasitic. Commonly viral infections like Mononucleosis which is commonly called Mono. Some bacterial infections include endocarditis, and syphilis. Some bacterial infections can form a large pus filled cavity, resulting in the inflammation of the spleen.  In addition malaria a parasitic infection can contribute to the removal of the spleen. 
- Cancer: Since the spleen filters the blood, many blood related cancers can form. In particular is Leukemia, which is a result of increase white blood cells that have taken over the position of normal blood cells. In addition the lymph nodes tissue of the spleen can become susceptible to Lymphoma, which is a cancer of lymph tissue. Cancers that directly effect the spleen can have a different origin. Cancers can be metastasized (spread) to the spleen by the infection of other organs or systems. Due to the function of the spleen, it can be removed in order to stop the spread of cancer and the inflammation that has occurred as a result of the cancer. 
- Inflammation: Many inflammatory disease that causes the enlargement of the spleen and many other organs. In particular is sarcoidosis, which is a chronic inflammatory disease that cause the inflammation of the tissue and produces granulomas that accumulate. Rheumatoid Arthritis has also been proven to cause the enlarge of the spleen. 
A direct hit to the spleen in any kind of physical activity can have damaging results. This damage often results in the rupture of the spleen, eventually leading to its removal. Also if excessive pressure is formed in the veins of the spleen or a blood clot is formed, the spleen can become damaged and unable to be repaired.  
All surgeries should be taken very seriously and be conducted in the most professional manner. Like all other surgeries, especially those requiring anesthesia, risks are present. The risk of complications with surgery is very low and correlates with the patient's health. In addition to risk during surgery the risk for a person to contract a severe infection goes up. One of the main factors regarding this issue is whether or not there is another disease present during. The second one would be the age of the person getting the procedure. Children have a higher risk then adults have in contracting a disease as a result of a splenectomy. However, the rate of infection rises no matter how good one’s health is. A common infection contracted by this procedure is streptococcus pneumoniae. This infection is a bacterium that causes pneumonia as well as other infections. Although some might experience these problems, other will have no reactions to the procedure. 
Removal of enlarged spleen:The oldest and most common way to remove the spleen is by hand, which is preformed under general anesthesia by a surgeon. The surgeon then will make the cut into the abdomen. From there he will tie off the artery entering the spleen to aid in the removal process and to stop the intake of red blood cells by the spleen. Then the ligaments that hold the spleen are detached and the spleen is then removed from the body. 
Partial splenectomy: Although rarely done it provides the patient with an adequate compromise between the discomforts of the enlarged spleen and makes the patient less vulnerable to an infection. 
Laparoscopic splenectomy: Laparoscopic splenectomy is a newer procedure to remove the spleen for the body and is getting more frequent. Instead of using long incision on the abdomen, many small incisions are made. Through these incisions small surgical equipment is passed through and with the help of video monitoring they are able to remove the spleen effortlessly. By doing this procedure the time spend in the hospital is reduced and the pain that follows the surgery is also reduced. In addition the risk of getting an infection is reduced and the scares left behind from the surgery are all small in length. There is one downside to this procedure and it is that most surgeons will not remove an enlarged spleen greater then 20 cm using this procedure. 
After the surgery patients will experience postoperative pain. However, everything is controllable with medication. One of the most important parts after surgery is to care for the incisions, in order to reduce the likely hood o getting an infection. Some patients will need blood transfusions to replace the damaged and defective blood cells. One of the care procedures stressed the most is to avoid vulnerability to infections. Patients who undergone the procedure must make frequent doctor visits if any sign of infection is seen. Sometimes children are kept on antibiotics till they are 16 as a way to prevent infection. Also a vaccine is given 5 to 10 years after the surgery to boost the bodies immune defense against pneumonia. 
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