Edema occurs in particular organs and tissues as a result of specific mechanisms. Some examples are described below.

Cerebral edema

In cerebral edema, fluid accumulates in and around the brain tissues. Abnormal metabolic states such as a reduced oxygen due to high altitude can cause this condition, which may lead to sleepinesss and even loss of consciousness.

Pulmonary edema

This is a condition that develops when the pressure in the blood vessels of the lungs is raised because the removal of blood via the pulmonary vein is obstructed. The condition is usually caused by left ventricular failure but it can also be caused by altitude sickness or inhalation of toxic chemicals.

Periorbital edema

This refers to swelling of the tissue surrounding the eyes. The swelling is most pronounced immediately after a person wakes up, possibly owing to the redistribution of fluid while they are lying down.

Edema in the cornea

Fluid may also accumulate in the cornea of the eye due to glaucoma, eye surgery or conjunctivitis. The swelling can cause a person to perceive bright lights and haloes.

Cutaneous edema

Skin may become swollen after an insect bite or when contact is made with an irritant such as a particular type of detergent (contact dermatitis). The skin may also swell up in cases of myxedema which refers to the skin’s increased tendency to retain water.

Lymphedema

Lack of lymphatic drainage in a certain region may cause the area to swell. This may be caused by obstruction due to the presence of a tumor or an enlarged lymph node, for example. Most often, it is caused by immobility affecting the pumping action of muscles.

Pregnancy induced edema

Pregnant women may become affected by fluid retention, particularly in the lower limbs and usually in the second and third trimesters.