Oedema

Oedema is waterlogging of the tissue due to a breakdown of the delicate balance described above. It can obviously arise from one of four reasons:

1.       Too high a mechanical hydrostatic pressure in the capillaries as happens, for example, if the venous drainage is blocked.

2.       Too low an osmotic pressure due to insufficient plasma proteins, particularly albumin.

3.       Blockage of the lymphatics.

4.       Damage to the capillary walls so that the plasma proteins leak out into the tissue and causes an osmotic pressure opposing the osmotic pressure of the protein in the blood stream.