Final answer:
Common causes of edema include (b)decreased capillary oncotic pressure, (c) increased capillary membrane permeability, (d) lymphatic obstruction, and (e) sodium retention. Decreased capillary hydrostatic pressure is not a typical cause of edema.
Step-by-step explanation:
The common causes of edema formation (increased filtration of fluid from capillaries and lymph into surrounding tissues) include several factors.
- Decreased capillary oncotic pressure: Caused by a decrease in the plasma proteins, which results in a reduction of colloid osmotic pressure counterbalancing the hydrostatic pressure, leading to loss of water from the blood to the surrounding tissues. This can occur in chronic and severe liver disease where the liver fails to manufacture enough plasma proteins.
- Increased capillary membrane permeability: Causes may include inflammation or damage to the capillary walls, allowing more fluid to leak out into the tissue spaces.
- Lymphatic obstruction: Obstructions can prevent fluid from draining effectively, leading to fluid accumulation in tissues.
- Sodium retention: Increases in the body's sodium levels can cause the body to retain water, contributing to edema, especially in cases such as heart failure and renal disease.
Note that decreased capillary hydrostatic pressure is not a typical cause of edema; instead, an increase in hydrostatic pressure favors fluid movement out of the capillaries.