Serosanguineous fluid is a type of wound drainage, or exudate, secreted by an open wound in response to tissue damage. As part of the wound healing process, open wounds commonly secrete a certain amount of exudate. However, the quantity and appearance of the drainage depends on the type of tissue damage. The presence of serosanguineous fluid is usually indicative of damage to capillaries, which are the smallest blood vessels found in the body. Capillaries are commonly injured during wound care, such as when changing a wound dressing.
Serosanguineous fluid typically appears during the inflammatory stage of the wound healing process as a by-product of dilated blood vessels. During the inflammatory stage of wound healing, damaged cells release inflammatory molecules that attract immune cells to the site of injury. This type of drainage is a sign of wound healing and is not a cause for concern when it appears in normal amounts.
Serosanguineous fluid is the most common type of exudate secreted by wounds, when compared to serous, sanguineous, and purulent drainage. Serous drainage is a clear, thin, and watery exudate that typically appears during the inflammatory stage of wound healing. While a small amount of exudate is normal, large amounts may indicate a high bioburden, an elevated number of potentially harmful bacteria on a non-sterile surface, which may suggest infection. Sanguineous drainage is constituted of fresh blood and typically appears during the inflammatory stage of deep wound healing. When produced outside of this stage of wound healing, sanguineous drainage may indicate wound trauma and damaged capillaries. Continuous sanguineous drainage from a wound may also suggest a hemorrhage, reflecting damage to an artery or vein. This phenomenon is referred to as hemorrhagic drainage. Lastly, purulent drainage is typical of infected wounds and consists of white blood cells, dead bacteria, and damaged cells.
