The spleen is an organ that plays a role in the body’s defense systems and blood maintenance. Understanding its normal appearance provides insight into its function. This article explores its external characteristics, placement, internal makeup, and how its look changes with health conditions.
Its Distinctive Shape and Color
An adult spleen is a soft, purplish-red organ, similar in size and shape to a clenched fist or an avocado. It measures 9-14 cm long, 6-8 cm wide, and 3-5 cm thick, weighing 150-350 grams. Its color comes from high vascularity, meaning it contains much blood.
The spleen’s exterior has a thin, fibroelastic capsule for protection and expansion. Its surface includes a smooth, convex diaphragmatic surface conforming to the diaphragm and ribs, and an irregular, concave visceral surface with impressions from neighboring organs. Notches are present along its superior border.
Where to Find Your Spleen
The spleen is in the upper left abdomen, beneath the left diaphragm and behind the stomach. It lies under the protection of the ninth, tenth, and eleventh ribs, making it not palpable during examination unless enlarged.
Its location also places it near the left kidney and the tail of the pancreas. Surrounded by peritoneum, it is somewhat mobile within the abdominal cavity, except at the hilum where blood vessels and nerves enter and exit.
Looking Inside: Red and White Pulp
Internally, the spleen has two primary tissue types: red pulp and white pulp. The red pulp, making up most of the spleen’s volume, appears dark red and spongy due to blood-filled venous sinuses. This tissue is a meshwork of reticular fibers containing macrophages, plasma cells, and various blood cells.
Within the red pulp are smaller, lighter-colored regions called white pulp. The white pulp consists mainly of lymphoid tissue, including lymphocytes and macrophages, organized around central arterioles. These immune cell aggregations cause the white pulp’s paler appearance.
When Its Appearance Changes
The spleen’s appearance changes with various health conditions. Enlargement, known as splenomegaly, is a common alteration where the spleen swells beyond its normal size and weight. A normal spleen measures up to 12 cm long and weighs around 70 grams, but an enlarged spleen can reach over 20 cm and weigh more than 1,000 grams. Infections, liver problems, blood disorders, or inflammatory conditions can cause this enlargement.
Color changes can also occur. With congestion or increased blood pooling, the spleen may appear darker than its usual purplish-red. In cases of injury, such as a ruptured spleen, the capsule can tear, leading to internal bleeding and blood accumulating in the abdominal cavity. This is a serious medical event.