What is wound exudate?

Most frequently referred to as wound “drainage,” exudate is a liquid produced by the body in response to tissue damage. It bathes the wound continuously, keeping it moist, supplying nutrients, and providing the best conditions for migration of new tissue to heal the wound. Open wounds should be moist, but not overly moist. A healthy healing wound should be moist without measurable exudate.

Exudate terminology

• Serous—thin clear watery plasma (seen in partial thickness wounds/venous ulcerations). A  moderate to heavy amount may indicate heavy bacteria level. This is normal in the first phases of wound healing.

• Sanguinous—bloody (fresh bleeding). This indicates new blood vessel growth or disruption of blood vessels.

• Serosanguineous—thin, watery, pale red to pink plasma with red blood cells.

• Seropurulent—thin, watery, cloudy, yellow to tan in color.

• Purulent—thick, opaque, tan, yellow, green or brown. This is never normal.

Significance of exudate color

• Clear/amber—serous exudate, often considered “normal,” but may be associated with infection by fibrinolysin-producing bacteria such as Staphyloccocus auerus; may also be due to fluid from a urinary or lymphatic fistula.

• Cloudy/milky—may indicate the presence of fibrin strands or infection.

• Pink/red—due to the presence of red blood cells; indicates capillary damage.

• Green—may be indicative of bacterial infection, e.g., Pseudomonas aeruginosa.

• Yellow/brown—may be due to the presence of wound slough or material from an enteric or urinary fistula

• Gray/blue—may be related to the use of silver-containing dressings.