An exudate is a fluid released by an
organism through pores or a wound, a process known as exuding or exudation.[1]Exudate is derived from exude 'to ooze'[2] from
Latinexsūdāre 'to (ooze out) sweat' (ex- 'out' and sūdāre 'to sweat').[3]
Medicine
An exudate is any
fluid that filters from the
circulatory system into
lesions or areas of
inflammation. It can be a pus-like or clear fluid. When an injury occurs, leaving skin exposed, it leaks out of the blood vessels and into nearby tissues. The fluid is composed of
serum,
fibrin, and
leukocytes. Exudate may ooze from cuts or from areas of infection or inflammation.[4]
Purulent or suppurative exudate consists of plasma with both active and dead
neutrophils,
fibrinogen, and
necroticparenchymal cells. This kind of exudate is consistent with more severe infections, and is commonly referred to as
pus.
Fibrinous exudate is composed mainly of
fibrinogen and
fibrin. It is characteristic of
rheumatic carditis, but is seen in all severe injuries such as
strep throat and
bacterial pneumonia. Fibrinous inflammation is often difficult to resolve due to blood vessels growing into the exudate and filling space that was occupied by fibrin. Often, large amounts of antibiotics are necessary for resolution.
Catarrhal exudate is seen in the nose and throat and is characterized by a high content of mucus.
Serous exudate (sometimes classified as serous
transudate) is usually seen in mild inflammation, with relatively low protein.[10] Its consistency resembles that of serum, and can usually be seen in certain disease states like
tuberculosis. (See below for difference between transudate and exudate)
Malignant (or cancerous) pleural effusion is effusion where
cancer cells are present.[11] It is usually classified as exudate.
Types of exudates: serous, serosanguineous, sanguineous, hemorrhaging and purulent drainage.
Serous: Clear straw colored liquid that drains from the wound. This is a normal part of the healing process.
Serosanguineous: Small amount of blood is present in the drainage; it is pink in color due to the presence of red blood cells mixed with serous drainage. This is a normal part of the healing process.
Sanguineous: This type of drainage contains red blood due to trauma of blood vessels, this may occur while cleaning the wound. Sanguineous drainage is abnormal.
Hemorrhaging: This type of drainage contains frank blood from a leaking blood vessel. This will require emergency treatment to control the bleed. This type of drainage is abnormal.
Purulent drainage: This type of drainage is malodorous and can be yellow, gray, or greenish in color. This is an indication of an infection.
Exudates vs. transudates
There is an important distinction between
transudates and exudates. Transudates are caused by disturbances of
hydrostatic or
colloid osmotic pressure, not by inflammation. They have a low protein content in comparison to exudates. Medical distinction between transudates and exudates is through the measurement of the
specific gravity of extracted fluid. Specific gravity is used to measure the protein content of the fluid. The higher the specific gravity, the greater the likelihood of
capillarypermeability changes in relation to
body cavities. For example, the specific gravity of the transudate is usually less than 1.012 and a protein content of less than 2 g/100 mL (2 g%).
Rivalta test may be used to differentiate an exudate from a transudate.
It is not clear if there is a distinction in the difference of transudates and exudates in plants.
^
abThe University of Utah • Spencer S. Eccles Health Sciences Library > WebPath images >
"Inflammation".
^
abHeffner J, Brown L, Barbieri C (1997). "Diagnostic value of tests that discriminate between exudative and transudative pleural effusions. Primary Study Investigators". Chest. 111 (4): 970–80.
doi:
10.1378/chest.111.4.970.
PMID9106577.
^
abLight R, Macgregor M, Luchsinger P, Ball W (1972). "Pleural effusions: the diagnostic separation of transudates and exudates". Ann Intern Med. 77 (4): 507–13.
doi:
10.7326/0003-4819-77-4-507.
PMID4642731.
^Roth BJ, O'Meara TF, Gragun WH (1990). "The serum-effusion albumin gradient in the evaluation of pleural effusions". Chest. 98 (3): 546–9.
doi:
10.1378/chest.98.3.546.
PMID2152757.
^Schiltz, S; Gaillard, I; Pawlicki-Jullian, N; Thiombiano, B; Mesnard, F; Gontier, E (December 2015). "A review: what is the spermosphere and how can it be studied?". Journal of Applied Microbiology. 119 (6): 1467–81.
doi:
10.1111/jam.12946.
PMID26332271.
S2CID42515027.
^Marschner, Horst (1995). Mineral Nutrition of Higher Plants.
ISBN0124735436.