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Pitting edema during and after the application of pressure to the skin.

Image: “Pitting edema during and after the application of pressure to the skin.” by James Heilman, MD. License: CC BY-SA 3.0

Definition: What Are Edemas?

Edema of the skin caused by inflammation

Image: Edema of the skin caused by inflammation. By: Klaus D. Peter. License: CC BY 3.0 DE

Edema (hydropsy) is the accumulation of fluid in the space outside of the body cells, in a compartment called the interstitial space or tissue space. The fluid emerges from the vessels and accumulates in the tissue space. The following preconditions are associated with the development of edemas:

  • Protein deficiency (decrease in colloid osmotic or oncotic pressure) due to nephropathies or hepatopathies.
  • Cell wall permeability (due to inflammations, sepsis, or allergies)
  • Obstruction to lymph flow
  • Increased hydrostatic pressure

Edema as an Accompanying Symptom

Edema may also accompany physical conditions that are not considered serious health problems. Edema may occur as part of the female cycle, or in people flying in airplanes, which is due to the body being constrained in an unnatural position for a prolonged period of time.

Edema accompanying menstruation

Edema is a typical accompanying symptom in gynecology and usually occurs in the second half of the menstrual cycle. It may not be visible but can cause unpleasant or painful feelings of tension. The accumulation of fluid also leads to weight gain. This is referred to as cyclic premenstrual edema or cyclical idiopathic edema, and it generally affects the legs, feet, hands, and/or chest. The symptoms always occur on both sides of the body. In the first part of the day, the upper part of the body is usually affected, and in the second part, the legs and feet are mostly affected.

Note: Hormone-related edemas always occur on both sides of the body.

The menstrual cycle impacts multiple processes

Blood vessels become more permeable in the second half of the menstrual cycle. Fluid and proteins move into the tissue. This process is more pronounced in some women than in others and is triggered by hormonal imbalance. Studies suggest that the release of excess aldosterone in the second half of the cycle encourages the formation of edema.

Aldosterone is formed in the adrenal gland and generally helps to regulate fluid balance. The increased release of serotonin may also contribute to the formation of edema. Serotonin influences the permeability of the vessels.

Edema during airplane flights

The causes of edema when flying are comparable to those of edema arising from a unilateral physical strain, such as standing for a long time while working. The muscle pump does not work properly during physical inactivity. As such, blood is trapped in the veins and the feet and legs become swollen.


The accumulation of fluid in the abdominal area is called ascites, and a swollen abdomen is a typical symptom. Liver cirrhosis, infectious diseases, and cardiac disease are possible causes.

Ascites as part of a liver cirrhosis

Ascites is common in advanced liver cirrhosis with portal hypertension. Moreover, obstructions of protein biosynthesis and changes in the water-electrolyte balance occur. However, tumors should be considered a differential diagnosis. Paracentesis (removing ascitic fluid for analysis) can be used in the diagnosis of ascites and in some cases a liver biopsy is necessary.

Infectious diseases should also be considered when ascites occurs. Typical therapy includes the treatment of the principal cause of ascites (for example diuretics and antibiotics) and diet adjustments depending on the cause.

Pleural Effusion

In pleural effusion, the amount of fluid in the pleural cavity exceeds the normal limit, and it is diagnosed if >200 mL of fluid is found in the pleura. Pleural effusion is a common presentation. In most cases, it is caused by cardiac insufficiency (bilateral), neoplasm (only on the left side), hypoalbuminemia, and inflammatory infections in the lung. Regarding differential diagnoses, systemic diseases as well as metabolic and abdominal diseases should be considered. In less severe cases of pleural effusion, the patient is usually not aware of the condition. However, in severe cases, the patient may complain of:

  • Dyspnea
  • Chest tightness
  • Chest pain when breathing (pleuritic pain)
  • Cough

Differences between pleural effusion and lung edema: In lung edema, the lung tissue, not the pleural cavity, is filled with fluid. Lung edema can be diagnosed quickly via lung ultrasound, which is a crucial modality. X-ray is also necessary. The mobile application of sonography (ultrasound) is needed in this scenario.

Note: Sonography has to be performed immediately if dyspnea and chest tightness occur.


Lymphedema comprises primary and secondary lymphedema. The primary form includes congenital familial lymphedema (Nonne-Milroy) and non-congenital familial lymphedema (Meige). The sporadic lymph edemas, which are caused by changes to the lymph vessels (hypoplasia or hyperplasia) also belong to the primary lymphedemas. Secondary lymphedemas could be:

  • Posttraumatic
  • Postoperative
  • Inflammatory
  • Neoplastic

Primary lymphedema usually occurs by age 35 and almost only affects women.

Characteristics of primary lymphedema

Primary lymphedema is characterized by the following symptoms:


It usually starts out in the toes, then spreads to the instep and ankles. Both legs are usually swollen.

Shape and consistency of the edema

The instep appears swollen. Eventually, a columnar deformation of the lower leg occurs. The skin is not discolored but may look pale. From an early stage, the edema feels hard and is barely dented with pressure. The skin feels cool.

Other symptoms

The affected body parts hurt. Patients complain of a feeling of heaviness.

Secondary lymphedema

Secondary lymphedema usually occurs after age 40. Men and women are affected equally. It usually develops on one side alone. However, this is not true when secondary lymphedema is caused by an inflammatory process. Secondary lymphedemas can sometimes be attributed to parasites (filariasis). In such cases, inflammatory changes to the lymph channels occur.

Treatment of lymphedemas

The type of therapy depends on the cause of the edema, and a wide range of conservative treatments are available. Surgery is usually only necessary when edemas lead to disability. Physical measures such as specialized pressure boots, gymnastics, and manual therapies are employed to remove blockages. The goal is to allow patients to manage their day-to-day routines and continue to work as much as possible.

The manual removal of blockages in secondary lymphedema can lead to metastasis if the underlying cause is malignancy.


Lipedema is the accumulation of fatty tissue, not fluid. Lipedemas are painful and typically occur symmetrically on the hips, thighs, and upper arms. They may also be accompanied by peripheral edemas. The term lipedema is derived from Greek and means ‘fat swelling’.

Differential Diagnosis of Anaphylactic Shock: Formation of Edema

Formation of edema as a similar disease pattern

Edema can occur during anaphylactic shock but may be triggered by other processes. Edemas are distinguished by their localization. They could be generalized (symmetric) or localized (one side or both sides). They could also occur in the periphery.

Peripheral edemas occur e.g. in the ankles, but can also be found in the lower legs. In bedridden patients, sacral edemas may occur. Another distinction is made according to palpation, depending on whether the edema can be dented with pressure. Furthermore, it is important to ascertain if the edema is soft or hard (indurated).

Quincke edema

Illustration of Angioedema

Image: Angioedema. By: BruceBlaus. License: CC BY 3.0

Quincke edema, also called angioneurotic edema, is an acute condition that can last for up to 3 days. It is a swelling that mostly affects the face (lips and eyelids), but the hands, feet, and genital region can also be markedly swollen. Quincke edema becomes lethal when upper respiratory tract swelling occurs.

Differential diagnosis of Quincke edema

Quincke edema can be genetically determined and is caused by a lack of enzymes, in which case it is referred to as hereditary angioedema. However, this condition is very rare. Quincke edema can also be caused by physical stimulation and it can accompany chronic infections or autoimmune diseases. The condition can also be idiopathic.

Reinke edema

Image of a Reinke edema

Image: Reinke Ödem. By: Welleschik. License: CC BY-SA 3.0

Reinke edema is a disease affecting the vocal folds. Fluid may accumulate on one or both sides, and the entire vocal cord may be affected. The patient notices the voice becoming deeper and speech may be impaired. Talking for a long time becomes challenging, and the patient may experience hoarseness.

Treatment of Reinke edema

Sprays containing cortisone are used to reduce the swelling. The patient is advised to avoid chemical vapors and other harmful influences such as smoking. The above-mentioned often cause Reinke edema in the first place. In severe cases, surgery can become necessary.

Perifocal edema

Perifocal edema is located in the healthy tissue surrounding the site of the disease. Perifocal edema can occur with e.g. abscesses, and also with tumors and hemorrhages. This edema may also be a complication following radiotherapy.

Pretibial edema

Pretibial edema is the accumulation of fluid in the subcutaneous tissue of the shinbone (tibia). Its occurrence usually indicates an obstruction of lymph flow. This condition is easily diagnosed but can be due to different causes.

Causes of pretibial edema

Right ventricular insufficiency is the most common cause (cardiac edema). Other causes include chronic venous insufficiency, endocrine diseases (myxedema), or causes within the lymphatic system. Diagnosing pretibial edema is crucial as the condition is occasionally indicative of very serious underlying causes.

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