Causes of Edema

The swelling is an accumulation of fluid in the interstitial spaces of the body. The term dropsy or hydrops (as synonymous with edema) indicates the accumulation of serous fluid in a body cavity, usually the peritoneum.

Edema can affect a limited area, such as a leg , or it can be generalized, when it occurs throughout the body. In this case, before edema is clinically evident, must collect several liters of fluid, which is why the weight gain usually precedes other manifestations of edema. When edema of all parts of the body is called anasarca.

Causes of Edema

Edema can be caused by increased hydrostatic pressure (eg due to venous stasis in the case of varicose veins of the lower limbs), or colloid osmotic pressure reduction (for example due to any disease that results in hypoalbuminemia) significant enough not allow more than the lymphatic vessels to drain fluid that accumulates in the interstitial spaces, inflated. It can be caused by obstruction of the lymphatic vessels, which can no longer drain the interstitial fluid (lymphedema) and excessive sodium retention. In these cases, the liquid that accumulates in the interstitial spaces is called transudate as it has a lower specific gravity was 1.012 kg / m 3, is low in protein and contains no inflammatory cells. Finally, you can have swelling in case of inflammation (inflammatory edema) because it increases vascular permeability. In this case the liquid exudate has accumulated since it has high specific gravity, greater than 1.020kg / m 3, is rich in proteins and inflammatory cells. The swelling takes specific names if they are not involved in the interstitial spaces, but the body cavities, is thus the hydrothorax (involving the pleura), the idroperitoneo (or ascites ) or hydropericardium, if it is extended to the subcutaneous tissue of 'body is called anasarca.

The localized forms of the limbs are almost always caused by disorders affecting the circulation of venous or lymphatic , such as a thrombosis, venous. Special cases of localized edema are those resulting from trauma as a swollen finger after a crushing, after hitting a bump or swelling in the head after an insect bite .

Two major forms of localized edema are the ' ascites by accumulation of fluid in the peritoneum , and  hydrothorax with the accumulation of fluid in the pleura , and these two events are generally expressions of major diseases.

The forms of generalized edema have as main causes:
heart disease resulting in a failure;
the conditions that lead to a severe renal failure ;
diseases that cause a strong reduction of albumin , such as nephrotic syndrome , severe impairment of hepatic or states of severe food shortages;
The generalized edema is called anasarca. Other cases of edema include malnutrition, edema, myxedema of  hypothyroidism and edema in Cushing's syndrome . A special case is the idiopathic edema or edema syndrome , which unlike other generalized edema is not related to diseases or risky situations for the patient.

Causes of Edema