Splenomegaly | All You Need to Know About Enlarged Spleen

What is the spleen?

Spleen is a lymphoid organ with a size of a hand fist, similar in structure to a lymph node and it is an important part of lymphatic and immune systems. The spleen lies behind the stomach in the left upper part of the abdomen which is medically called the upper left hypochondrium. The human spleen weighs approximately 6 ounces (170 grams) and it is covered with a dense fibroelastic tissue called the splenic capsule. The splenic capsule is semi-translucent letting the spleen express its reddish-purple color.

Function of spleen

Spleen carries out a lot of important immunological and hematological tasks, yet it is not essential and humans can live without it. Functions of the spleen include the following:

  1. Spleen is believed to be a reservoir sac of blood as storage of blood is a characteristic function of the spleen. Spleen normally stores up to 240 ml of red blood cells. In case of bleeding or hypovolemia spleen squeeze itself to pour blood into the circulation to compensate for what is lost.
  2. The spleen is where some white blood cells are matured and activated, therefore if the spleen is excised or damaged the patient will be more susceptible to getting an infection. Circulating macrophages are hosted in the spleen to get rid of microbes. Spleen also contains macrophage in its own tissue to recognize and phagocytose microorganisms.
  3. Spleen is considered a large lymph node because it acts as a station in which blood is filtered from many pathogens. Spleen also clears the body from tissue debris and cellular wastes especially mal-formed red blood cells. Worn red blood cells with degraded hemoglobin lose their iron content in the spleen to be released in the bloodstream to contribute to forming new RBCs. Patients with damaged spleen lose the privilege of quality controlling red blood cells.

What is splenomegaly?

Splenomegaly is a common medical condition in which the spleen is enlarged in size or weight. The hypertrophied spleen resulted from acute or chronic overload on the spleen which is caused by a wide variety of diseases. The largest dimension of the spleen doesn’t normally exceed 11 cm whereas in splenomegaly it may reach up to 25 cm. Surgeons may also consider spleens weighing more than 400 grams as splenomegaly. Splenomegaly is a serious medical condition that may cause potentially fatal complications such as splenic rupture thus patients should seek medical attention if they suspect an enlargement in their spleen.

Statistics of splenomegaly

Splenomegaly is a well-known medical condition worldwide yet it is more defined as a tropical disorder that is more common in Asia, Africa, and South America than in Europe and North America. Since splenomegaly is a chronic condition that may need negligence of the underlying cause, then it is more prevalent in developing regions. A study showed that the incidence rate of splenomegaly in the USA is 2% which is mainly resulted from hematological causes. The mortality rate of splenomegaly is considerable as patients who have uncontrolled splenomegaly are exposed to the risk of a 1.8% death rate within 30 days.

Degrees of splenomegaly

Splenomegaly is classified according to its degree of enlargement based on clinical physical examination or radiology. Physicians could classify splenomegaly roughly into mild, moderate, and severe depending on the length of the longest dimension. Length of the longest dimension in mild splenomegaly 11-15 cm, moderate splenomegaly 16-20 cm while severe splenomegaly is more than 20 cm.

Hackett’s grading system is a more specific tool to classify splenomegaly into 5 grades. Grade 1 is the mildest form of splenomegaly in which the spleen is barely palpated on deep inspiration. Grade 2 includes spleen enlargement and extension downward and toward the midline to be midway between the umbilicus and the costal margin (lower border of the ribs). Grade 3 includes further enlargement of the spleen. Grade four is characterized by spleen enlargement to reach the umbilicus. Grade 5 is the most severe and life-threatening form of splenomegaly in which the spleen extends beyond the umbilicus toward symphysis pubis.

» Now, let’s discuss causes, diagnosis, symptoms and treatment options of splenomegaly