What Is It, Causes, Signs, Symptoms, and More
Author:Ahmed A. Abu Ajeene, M.B.B.S
Editors:Anna Hernández, MD,Emily Miao, PharmD,Kelsey LaFayette, DNP, RN, FNP-C
Illustrator:Jessica Reynolds, MS
Copyeditor:David G. Walker
What is anasarca?
What is the difference between anasarca and edema?
Anasarca is a form of extreme, generalized edema, which is when fluid accumulation causes a palpable swelling throughout the entire body.
In general, edema occurs when there are changes in one of the two forces that determine fluid movement across capillary walls: hydrostatic pressure and oncotic pressure. Capillary hydrostatic pressure causes fluid to flow from the capillaries and into the interstitial space, or the space between cells; whereas capillary oncotic pressure draws this fluid back into the capillary. Oncotic pressure is a type of pressure exerted by the cells and proteins present in blood, like albumin, which is produced in the liver. When taking into account these two forces, only a very small amount of fluid leaks into the interstitial space, and that fluid is typically picked up by the capillaries of the lymphatic system.
What causes anasarca?
Anasarca arises from disorders that cause an imbalance between hydrostatic and oncotic pressure, causing more fluid to leak from the capillaries into the interstitial space. Hydrostatic pressure can increase in cases of heart and kidney failure as well as in cases of venous obstruction. On the other hand, oncotic pressure decreases when there’s a low concentration of albumin in the blood, or hypoalbuminemia. This can happen when the production of albumin is decreased, like in cases of liver cirrhosis as well as with nephrotic syndrome where albumin and other proteins are lost in the urine. Other causes of anasarca include burns, trauma, and malignancy: all of which increase capillary permeability, thereby allowing more fluid to leak from the capillaries. Although rare, anasarca can be a side effect of certain medications, including steroids and calcium channel blockers.
How is anasarca diagnosed?
The diagnosis of anasarca begins with a medical history and physical exam, which may show symptoms of anasarca, including weight gain, changes in heart rate, failure of multiple organs, and generalized swelling all over the body. In cases where there’s fluid accumulation around the lungs, there may be signs of pulmonary edema, including shortness of breath, coughing, wheezing, and chest pain. In extreme cases, the extra fluid around the lungs can impair gas exchange, leading to acute respiratory distress syndrome, which can be life-threatening. A physical exam is typically followed by blood tests to assess kidney and liver functions and determine the underlying cause. Finally, additional tests may be performed, including an echocardiogram to assess heart function, and a chest X-ray if pulmonary edema is suspected.
How is anasarca treated?
The treatment of anasarca focuses on addressing the underlying cause when possible. For example, in cases where anasarca is caused by heart failure, treatment may include diuretic medications, including furosemide (i.e., loop diuretic) and spironolactone (i.e., potassium-sparing diuretic) as well as vasodilator medications, like ACE inhibitors. These medications cause dilation of the blood vessels, making it easier for fluid to return into the capillaries. Individuals undergoing treatment of anasarca may lose up to two to three liters of fluid in a 24-hour period due to the excess fluid accumulation.
What are the most important facts about anasarca?
Anasarca is a medical condition characterized by an extreme and generalized form of edema, which is fluid accumulation in the interstitial space. This fluid accumulation is caused by disorders that lead to an imbalance between the two forces controlling the movement of fluid across blood vessels called hydrostatic pressure and oncotic pressure. The most common causes of anasarca include heart failure, renal failure, cirrhosis, and pregnancy. Diagnosis of anasarca is mostly clinical, and it is based on the medical history and signs of generalized edema on a physical exam. Treatment of anasarca focuses on addressing the underlying cause of fluid accumulation when possible.
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Resources for research and reference
Kattula, S. R. S. T., Avula, A., & Baradhi, K. M. (2022, February 10). Anasarca. In StatPearls. Retrieved February 27, 2022, from https://www.ncbi.nlm.nih.gov/books/NBK519013/Hemodynamic Disorders, Thromboembolism, and Shock. (2018). In Kumar, V., Abbas, A. K., Aster, J. C., & Perkins, J. A. (Eds.), Robbins basic pathology (10th ed., pp. 98-100). Elsevier.