The spleen is the soft, purplish-red organ tucked just under the rib
cage on the left side of the abdomen. It is about the size of the heart and
is made up of a spongy material that can hold up to three gallons of blood.
Of all the abdominal organs, the spleen is the one most easily and most
frequently injured. We usually do not hear much about the spleen unless we
know of someone who was in a car accident or fell causing the spleen to rupture.
Because this organ is soft and mushy, it usually cannot be repaired surgically
and is removed to stop the blood loss.
What exactly does the spleen do? In ancient times, the spleen was
thought to be the seat of emotions and feelings, but its real functions have
only recently been recognized. One of these is to serve as a reservoir for
blood in case of emergencies. When a child experiences a sudden blood loss,
the body signals the spleen to contract, forcing replacement blood into the
circulation.
A second important function of the spleen is to filter worn-out red
and white blood cells, and platelets from the blood. In the process of destroying
these cells, the spleen breaks them down, returns needed iron to the blood
and disposes the rest as waste. In a disease such as infectious mononucleosis,
the spleen becomes overactive and traps a higher number of white blood cells
than usual. In the process, the spleen becomes swollen and enlarges.
A third job of the spleen is to store platelets (the part of the blood
that helps us clot our blood) and a large percentage of the body's platelets
are normally found there, ready to be sent where needed.
But probably the most important role of the spleen is to bring blood
into contact with the spleen's lymphocytes. When the blood contains any foreign
invader, such as a virus, bacteria or parasite, the spleen's T-cell lymphocytes
become activated. This contact causes the lymphocytes to attack the foreign
invaders or produce antibodies directed against them. The importance of the
spleen in guarding against germs in the bloodstream is so great that children
who lose their spleen by surgery after severe internal abdominal injury or
whose spleen is destroyed by the effects of sickle cell disease are at increased
risk for certain dangerous bacterial infections.
Finally, the spleen manufactures red blood cells for the fetus during
the last months of fetal life. After birth that function is taken over by
the bone marrow. However, in cases of a bone marrow breakdown, the spleen
can revert back to its fetal function.
Many diseases affect the spleen, including bacterial, parasite and
viral infections, tuberculosis, malaria, rheumatoid arthritis, liver disease,
and certain fungal infections. In addition, a number of blood diseases affect
the spleen, including hereditary spherocytosis (a condition in which the
red blood cells are relatively delicate and are damaged or destroyed when
they pass through the spleen) and chronic immune or idiopathic thrombocytopenic
purpura (ITP) (a disorder that results in destruction of platelets, which
are blood cells involved in clotting.)
An injured spleen causes extensive bleeding. The signs and symptoms
of an injured spleen include abdominal pain, guarding (holding a hand over
the area), tenderness in the upper left part of the abdomen, left shoulder
pain and signs of shock and blood loss. This can be a major life-threatening
event.
If the spleen continues to bleed, surgery to remove the spleen is
necessary. When the spleen is removed, the body is equipped to take over
the functions of the spleen with the liver and lymphatic system, but there
is an increased risk of infection. The spleen plays an important role in
protecting against certain kinds of organisms including pneumococci,
meningococci, and Hib (Haemophilus influenzae, type B, which can cause infections
of the bloodstream (sepsis) and brain (meningitis), as well as other parts
of the body (pneumonia). These diseases are very serious in any child, but
they tend to be more common, more severe and have a greater risk of causing
permanent damage or death after a splenectomy. Since pneumococcal, meningococcal,
and Hib vaccines are quite safe, they should be given very high priority
for children who have had their spleens removed. The pneumococcal vaccine
is repeated every five years. In addition, following splenectomy most youngsters
will require a long term penicillin type antibiotic to prevent infections
by these bacteria.
