Which of the following is NOT a cause of edema?

Decreased capillary permeability is indeed not a cause of edema. To understand this, it's essential to recognize the role of capillary permeability in fluid movement. Capillary permeability refers to how easily fluids and solutes can pass through the capillary walls.

When capillary permeability is decreased, this means that the capillary walls are less permeable or have reduced ability to allow fluid, proteins, and other substances to pass into the interstitial tissue. As a result, fewer fluids would escape from the bloodstream into the surrounding tissues, which reduces the likelihood of edema developing.

In contrast, factors like increased capillary filtration pressure, increased capillary permeability, and decreased capillary colloidal osmotic pressure can all lead to an accumulation of fluid in the interstitial spaces, thereby promoting edema. Increased capillary filtration pressure pushes more fluid out of the capillaries, increased capillary permeability allows more fluid and proteins to leak out, and decreased colloidal osmotic pressure reduces the attraction of fluid back into the capillaries. Therefore, decreased capillary permeability would not contribute to the formation of edema, making it the correct answer to the question.