Edema: Types, Causes, Risk Factors, Complications, Diagnosis and Treatment

Formerly known as dropsy, it is an inflammation of the body’s tissues due to excessive interstitial fluid retention.

Edema can occur locally, often affecting the extremities (peripheral edema) or the entire body ( anasarca ).

The body has two main compartments between which fluid is exchanged: the intravascular and the extravascular compartments.

Intravascular compartments include the cardiac chambers and the vascular system itself, while extravascular compartments include all the others.

Fluid moves quickly between these compartments, and the extent of this movement is primarily determined by the balance between hydrostatic and oncotic pressures.

Hydrostatic pressure refers to the pressure exerted by gravity on a fluid in equilibrium, and it tends to cause the fluid to leak into the extravascular compartment.

Moreover, oncotic pressure is an osmotic type of pressure where plasma proteins pour fluid into the intravascular compartment.


Typically, these pressures balance relatively evenly, with a net leakage into the extravascular compartment of approximately 1% of the plasma.

The lymphatic system then carries this extra fluid back to the intravascular compartment through the thoracic duct.

Therefore, any change in the balance of these pressures that results in a more significant net leakage than the lymphatic system can effectively transport can cause edema.

Edema is an abnormal accumulation of fluid between tissues. It mainly refers to the skin or mucous membranes, where it causes swelling.

Edema mainly affects the skin or mucous membranes, which causes swelling.

Types of edema

Edema is inflammatory and localized when it is a defense reaction against an insect bite.

On the other hand, generalized edema shows retention of hydrosodium and an increase in the permeability of the capillaries, often associated with venous insufficiency.

They are mainly found in cases of heart failure or venous involvement.

Quincke’s edema is an acute allergic manifestation with swelling of the face.


Possible causes of edema are:

  • The hydrostatic pressure of the veins causes a decrease in the reabsorption of liquids.
  • Obstructing the venous O weep.
  • Congestive heart failure
  • Varicose veins
  • Decreased oncotic pressure.
  • Cirrhosis.
  • Malnutrition.
  • Nephrotic syndrome (loss of protein in the kidneys) or acute glomerulonephritis.
  • Inflammation (active secretion of fluid in the interstitial space).
  • Allergic conditions (for example, angioedema).
  • Lyme’s disease.
  • All other forms of inflammation (tumor or swelling, one of the inflammation’s main characteristics).

An increase in hydrostatic pressure can result from heart failure or venous obstruction.

The decrease in oncotic pressure occurs in patients with malnutrition, which results in an abnormally low level of blood proteins.

In addition, any condition that affects the permeability of the vascular membranes, including inflammation or trauma to the tissues, can also cause more fluid to “leak” out of the intravascular compartment.

When the body realizes that this filtration is occurring, the kidneys, in turn, retain more water and sodium to compensate for the loss of fluid, causing more blood to circulate and more leaks to occur.

Edema, specifically related to the alteration of the lymphatic system in the extraction of interstitial fluid, is known as lymphedema.

Medications can also cause edema:

  • Calcium channel blockers.
  • Corticosteroids and anti-inflammatory or steroidal medications cause sodium and fluid retention.
  • An abnormal decrease in lymphatic drainage.

Risk factor’s

Edema itself is not a disease but a symptom.

Less severe forms of edema can be the result of lifestyles and general health factors, such as:

  • Staying in one position (sitting, standing, or supine) for too long.
  • Increased sodium intake.
  • Hormonal changes due to menstruation.
  • The pregnancy.

Edema can also occur as a side effect of several different medications, including:

  • Vasodilators.
  • Calcium channel blockers.
  • Estrogen-based medication.
  • Non-steroidal anti-inflammatory drugs.
  • Certain diabetes medications.

However, edema can also be a sign of severe underlying medical conditions, such as:

  • Congestive heart failure
  • Cirrhosis.
  • Kidney disease
  • Chronic venous insufficiency.
  • Chronic lung diseases.
  • A damaged lymphatic system.


Left unchecked, edema can cause the overlying skin to stretch and develop infections or ulcerations.

Also, decreased blood circulation can lead to blood clots in the body’s deep veins, known as deep vein thrombosis.

Diagnosis of edema

To make an accurate diagnosis, the doctor takes a medical history with the following data:

  • Date of appearance of edema.
  • The conditions that intensify it: the time of day, at rest or in activity, if it is associated with the hormonal cycle, if it is unilateral or bilateral if you observe that it depends on the hormonal cycle or temperature.
  • The evolution of edema over time.
  • The existence of previous systemic diseases such as heart failure or liver cirrhosis, kidney and thyroid diseases, Graves’ disease, obstructive sleep apnea, the presence of hypertension, and diabetes mellitus.
  • Medication history, among others.
  • The change in diuretic patterns: abnormal urination and period between one urination and the other.
  • The lifestyle of the patient: sedentary lifestyle, healthy diet.
  • Family history.

It is essential to determine the physical condition of the patient, so a physical examination is performed to evaluate the following symptoms and signs:

  • Palpation.
  • Changes in the skin: the temperature, color, and texture of the skin (fibrotic, shiny, thickened, or warty).
  • The location and extent of edema to determine response to treatment.
  • If the indentation remains in the edematous area after pressure is applied.
  • Examination of the feet, if the ankles have very prominent swelling of the ankle fat.
  • The presence of mixedemas.

Recommendations for diagnostic tests are:

Lab tests

Laboratory tests diagnose systemic causes of edema: brain natriuretic peptide, urinalysis, creatinine, liver enzymes, and albumin.

In patients presenting with an acute onset of unilateral upper or lower extremity inflammation, a dimer enzyme-linked immunosorbent assay.


Venous ultrasound is the imaging modality of choice for evaluation.


Indirect radionuclide lymphoscintigraphy, showing absent or delayed filing of the lymphatic channels, is the method of choice to evaluate lymphedema when the diagnosis cannot be made clinically.

Magnetic resonance

Patients with unilateral lower extremity edema who do not demonstrate proximal thrombosis on duplex ultrasound may require additional imaging to diagnose the cause of the edema.

MRI can help diagnose musculoskeletal etiologies, such as a ruptured gastrocnemius or a popliteal cyst.

T1-weighted magnetic resonance lymphangiography can be used to visualize lymphatic channels when lymphedema is suspected directly.

Other studies

Echocardiography is used to assess the blood pressure of the lung and is recommended in patients with obstructive sleep apnea and edema together.

Edema treatment

The underlying disease should guide the treatment of edema:

Chronic venous insufficiency

Diuretic therapy should be avoided in patients with chronic venous insufficiency unless a comorbid condition requires it.

Mechanical therapies are recommended, including leg elevation and compression stockings with 20–30 mm Hg for mild edema and 30–40 mm Hg for severe edema complicated by ulceration.

However, this compression therapy is contraindicated in patients with peripheral arterial disease.

Ankle-brachial index measurement should be considered in patients with risk factors for the peripheral arterial disease before prescribing compression therapy.

For mild to moderate chronic venous insufficiency, horse chestnut seed oral extract may be an alternative or complementary treatment to compression therapy.

Caring for the skin and wounds caused by venous ulcers is essential in preventing cellulite and dermatitis.

To treat eczematous dermatitis (stasis), characterized by dry, inflamed, and scaly skin covering superficial varicose veins, it should be hydrated daily with emollients and topical steroid creams for severely inflamed skin.


Lymphedema treatment lies in complex decongestant physiotherapy, performed using lymphatic massage and bandages.

This is intended to improve fluid resorption.

Compression stockings of 30 to 40 mm Hg are used in the maintenance phase.

Deep venous thrombosis

Deep vein thrombosis is treated with anticoagulant therapy such as heparin or warfarin to prevent the development of the post-thrombotic syndrome.

Drug-induced edema

Treatment includes stopping the medication if possible.

Other causes

There is no treatment to control lipedema.

Regional pain is treated with physical therapy and antidepressant and systemic steroid medications.


  • Such as antidepressants (monoamine oxidase inhibitors, trazodone), antihypertensives (beta-adrenergic blockers, calcium channel blockers, clonidine, hydralazine, methyldopa, minoxidil), antivirals (acyclovir).
  • Also, chemotherapy (cyclophosphamide, cyclosporine, cytosine arabinoside, mithramycin), cytokines (stimulating factor of granulocyte colonies, and macrophages, alpha interferon, interleukin-2, interleukin-4), hormones (androgens, corticosteroids).