What is Third Spacing of Fluid? Causes, Symptoms & Treatments

Third spacing is not a term you might hear in everyday conversation, but it’s an essential concept for medical professionals and those with health challenges to be aware of. It’s a condition that can lead to severe symptoms if untreated, but there are treatments available that can help improve the problem.

In this blog post, we’ll discuss third spacing, its major causes, its associated symptoms, and some of the most common ways to treat it. With this information, you’ll better understand how to recognize and address these issues if they arise in yourself or someone close to you.

What is Third Spacing?

Third spacing describes the accumulation of intravenous fluids outside of circulation. This occurs when fluid shifts out of the bloodstream and into interstitial spaces in organs and tissues. In addition, third spacing may also affect one organ, an area of the body, or multiple organs at once.

Healthcare professionals initially used the term “third space” to describe a non-functional compartment in the body where intravenous fluids would pool during major surgery. However, research has been unable to identify or localize these areas with tracer studies.

While some experts have suggested abandoning the terms “third space” and “third spacing,” others believe that they should be used to refer to anatomical spaces where extracellular volume can accumulate, such as :

  • bowel lumen, the space within the intestine
  • peritoneum, the membrane lining the abdomen and abdominal organs
  • pleura, the membrane lining the lungs and chest cavity

Ultimately, third spacing is a phenomenon that affects the body’s fluid balance by shifting intravenous fluids out of circulation into interstitial space. This may occur in one organ or multiple organs at once. Further research is needed to understand this phenomenon better.

Important To Know the fluid compartments: Intracellular, Intravascular, and the Interstitial 

To understand the root of third spacing, comparing and contrasting intracellular and extracellular spaces is essential. The latter comprises both intravascular and interstitial or third space.

  • The intracellular space: Cellular fluid levels are paramount within the intracellular area – its optimal level prevents cells from becoming dehydrated or swollen, which could cause cell rupture.
  • The intravascular space: In the intravascular area, fluid regulation is also essential as it influences preload, cardiac output, blood pressure, and perfusion.
  • The interstitial space: Lastly, the interstitial space provides a non-functional gap between the intracellular and intravascular space, commonly referred to as ‘the third space.’

With all of these elements in mind, it becomes clear why third spacing has the potential to occur. By monitoring and balancing all three spaces, we can work to prevent it.

What Causes Third Spacing?

A wide range of conditions can lead to third spacing, usually those that cause severe trauma, obstruction, or inflammation, such as:

  • intestinal obstructions
  • burns or other tissue trauma
  • congestive heart failure
  • vein obstructions
  • valvular heart disease
  • sepsis
  • kidney failure or dialysis
  • severe dehydration
  • pancreatitis
  • -abdominal surgery
  • allergic reactions
  • a decrease in plasma proteins
  • lymphatic blockages
  • increased capillary permeability
  • liver cirrhosis.

Symptoms & Phases

There are two distinct phases of third spacing.

Phases -1

In Phase 1 – commonly known as fluid loss – fluids and proteins leave the bloodstream and enter the interstitial spaces or body cavities. This occurs shortly after surgery, trauma, or severe inflammation and typically lasts 48-72 hours.

During this period, capillaries become more absorbent and vulnerable to leakage caused by inflammation, trauma, or blockages.

During this stage, signs and symptoms may include:

• Increased heart rate

• Increased respiration

• Decreased blood pressure

• Hypotension

• Diaphoresis

Phases -2

Phase 2, also known as reabsorption, is the process in which capillaries heal and restore their average permeability. Blockages are cleared, and fluid volume shifts back to the blood, where the kidneys eventually expel it. This phase of recovery typically occurs when someone is hospitalized.

Symptoms of phase 2 include:

• weight loss

• Improved urine output

• urinating more fluids than are being consumed

Healthcare professionals may monitor someone for signs that the circulatory system has become overwhelmed, such as:

  • shortness of breath
  • increased central venous pressure, the blood pressure in the heart’s right atrium
  • distended or swollen neck veins
  • electrolyte imbalances or dehydration
  • changes in heart rhythm or electrical abnormalities

Diagnosis and treatment of 3rd spacing

It is often hard to recognize if someone is experiencing third spacing. This can make it more difficult for the condition to be diagnosed early and risks of complications minimized.

Symptoms that may indicate third spacing, which doctors or nurses might detect during or after surgery or significant disease/trauma, include low blood pressure, swelling (edema) in the abdomen and other body parts, dehydration, and electrolyte imbalance.

The ideal treatment usually depends on the cause and stage of the condition.

In phase 1, management typically involves administering IV fluid such as crystalloid or colloid. Healthcare professionals may also give people hypertonic fluids before anesthesia and isotonic fluids during surgery.

During Phase 1, healthcare professionals should monitor several vital signs carefully to prevent complications, like:

  • urine output and gravity
  • potassium levels
  • levels of urea nitrogen in the blood
  • creatine levels
  • breath and chest sounds

In Phase 2, treatments usually involve monitoring by medical staff. If severe symptoms arise, a diuretic such as furosemide might be administered.

Movement Of Fluid in Third Space

Fluctuations in the body’s fluid levels occur when liquids transition from one space to another. This is accomplished by combining hydrostatic and osmotic pressure gradients propelling water through semi-permeable membranes.

When fluids leave the intravascular compartment – i.e., the blood vessels – it can lead to dangerously low blood pressure and harm vital organs such as the brain, heart, and kidneys; if they depart from cells (the intracellular compartment), cellular processes will slow down or stop due to dehydration; extra liquid in the interstitial space leads to swelling (edema); and if too many seeps into brain cells, increased cranial pressure may develop.

The Medical Experts treat it by Third space fluid replacement or diuretics may.

Frequently Asked Question

What is the concept of third-space fluid shift?

Third-space fluid shift refers to the redistribution of body fluid to a non-contributory space, making it inaccessible to the circulatory system. This phenomenon, frequently encountered in clinical settings, requires prompt identification to mitigate potential adverse effects.

Is third spacing a significant concern?

When left untreated, third spacing can give rise to severe complications. Understanding the following information is crucial for restoring the patient’s equilibrium.

How does Anasarca differ from third spacing?

Anasarca typically occurs when capillary filtration/leakage surpasses the fluid elimination through lymphatic drainage. As a result, fluid accumulates in the interstitial spaces, commonly known as “third spacing.”

Can Lasix aid in managing third spacing?

Albumin administration facilitates fluid movement from the interstitial space into the intravascular space. If the kidneys cannot eliminate the excess fluid independently, a low dosage of a loop diuretic like furosemide (Lasix) may assist.

Final Words

Third spacing is an imbalance of Third spacing fluid between the intravascular, interstitial, and intracellular spaces in the body. It occurs when there is too much fluid or insufficient fluid in one of these compartments. This has several potentially harmful effects, most commonly seen in sepsis (blood poisoning), burns, trauma, and surgery.

Specific lifestyle changes can also help reduce their risk of developing it. Diagnosis is often difficult due to the lack of symptoms early on. Still, doctors may detect signs such as low blood pressure, swelling (edema), and electrolyte imbalance during or after surgery/significant trauma.

Overall, people need to understand the signs and symptoms of third spacing to seek medical attention early on if necessary. Maintaining a healthy lifestyle that promotes hydration and electrolyte balance is also essential. Proper diagnosis and treatment can help improve outcomes for those affected by this condition.


  • https://en.wikipedia.org/wiki/Fluid_compartments
  • https://www.wikidoc.org/index.php/Interstitial_fluid
  • Darovic, G. O., & Zbilut, J. P. (2002). Hemodynamic monitoring: Invasive and noninvasive clinical application (3rd ed.). Philadelphia: Saunders Elsevier.
  • Porth, C. M., & Litwack, K. (2018). Pathophysiology: Concepts of altered health states (10th ed.). Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins.
  • Sterns, R. H. (2020). Etiology, clinical manifestations, and diagnosis of volume depletion in adults. Retrieved from: https://www.uptodate.com/contents/etiology-clinical-manifestations-and-diagnosis-of-volume-depletion-in-adults
  • Sterns, R. H. (2020). Pathophysiology and etiology of edema in adults. Retrieved from: https://www.uptodate.com/contents/pathophysiology-and-etiology-of-edema-in-adults

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