Why do you expect edema when osmotic pressure decreases but not when it rises?

Answer 1

this is because when osmosis takes place there is a movement of water from the extra vascular space into the intra vascular space thus reducing the amount of fluid that is present in the tissues. So when there is a low osmotic pressure, there is less water moving from the extra vascular space into the vessels. But if there is an increase in pressure, it will enable water to move into the vessels thus reducing the risk of having edema.