Differences Between Transudates and Exudates

The closed cavities of the body—namely, the pleural, pericardial, and peritoneal cavities—are each lined by two membranes, visceral membrane and parietal membrane. There is a small amount of fluid between the membranes that is an ultrafiltrate of plasma. When the production and reabsorption of the ultrafiltrate is not balanced, fluid may accumulate, resulting in effusion. Effusions may be classified as transudate or exudate.

Classifying a serous fluid as transudate or exudate can provide a valuable initial diagnostic step and aid diagnosis of underlying cause. Followings are the differences between transudate and exudate :

Features	Transudate	Exudate
Cause	Usually develop from imbalances in hydrostatic and oncotic forces in circulation.	Usually develop from increased capillary permeability or decreased lymphatic reabsorption.
Associated with	-Congestive heart failure -Fluid overload -Nephrotic syndrome -Hepatic cirrhosis -Malnutrition	-Microbial infections -Membrane inflammations -Malignancy -Connective tissue diseases.
Appearance	Clear, thin-colored, pale yellow	Turbid, hemorrhagic, straw colored
Fibrinogen	Low content of fibrinogen (low tendency to clot)	High content of fibrinogen (high tendency to clot)
Specific gravity	<1.012	>1.012
pH	>7.3	<7.3
Glucose content	Same as plasma	Low (less than 60 mg/dl)
Total Protein	Less than 3 gm/dl	More than 3 gm/dl
Fluid/Serum Protein	<0.5	>0.5
LDH	<0.67 x UNL Serum	>0.67 x UNL Serum
WBC count	<1000/ul	>1000/ul
Differential count	Mesothelial cells or lymphocytes	Polymorphs, lymphocytes or RBCs
Culture	Sterile	Positive