ABSTRACT

In health, a small amount of fluid between the parietal and visceral surfaces of body cavities acts as lubricant to facilitate the motion of internal organs against each other and the body cavity walls. The chemical composition of body cavity fluids is determined by the permeability of capillary walls, which can be passed by nonprotein solutes such as glucose, urea, creatinine, electrolytes, bicarbonate, calcium, and phosphate. Differentiation between transudative and exudative effusions is highly relevant because exudates are commonly produced by local inflammatory processes within the respective body cavity, whereas transudation is commonly elicited by systemic disease or mechanical obstruction. The amount of protein spilling into the body cavity depends on the protein content of the interstitial fluid of the organs, which is mainly affected by the increase of hydrostatic pressure. Lymphorrhage describes the leakage of lymphatic fluids into a body cavity. Uroabdomen occurs when urine spills into the abdominal cavity subsequent to trauma, urolithiasis, or neoplasia.