Defining Extravasation of Blood
Extravasation is a medical term that describes the leakage of fluid from its container, such as a blood vessel, into the surrounding tissue [1.2.4]. Therefore, extravasation of blood is the process of blood escaping from an artery or vein and seeping into the adjacent extravascular space [1.2.6]. This is different from the normal, controlled movement of cells like leukocytes (white blood cells) out of vessels during an inflammatory response, a process also called extravasation or diapedesis [1.2.4]. When it involves blood or certain medications, it is often an unintended and problematic event, most frequently associated with intravenous (IV) therapy [1.2.2].
Common Causes of Blood Extravasation
Blood extravasation can occur for several reasons, ranging from physical trauma to complications from medical procedures [1.3.4, 1.3.6].
Intravenous (IV) Therapy Complications
This is one of the most common contexts for extravasation. It happens when the IV cannula (catheter) punctures the vein wall, gets dislodged from the vein, or when the vein itself is fragile and leaks [1.2.5, 1.3.4]. The leakage of infused fluids or medications into the surrounding tissue is technically called infiltration; when that substance is a vesicant (an agent that causes tissue damage), it is called extravasation [1.4.4, 1.4.6]. If the infused substance is blood itself during a transfusion, significant leakage can lead to serious complications [1.2.7]. The incidence rate of extravasation during IV therapy is reported to be between 0.1% and 6.5% [1.2.2, 1.3.5].
Traumatic Injury
Any injury that ruptures or damages blood vessels can cause blood to extravasate. This is the underlying mechanism of a common bruise (contusion), where trauma breaks capillaries, leading to a localized collection of blood in the tissue.
Medical and Patient-Related Factors
Certain factors increase the risk of extravasation. Patient-related risks include fragile veins (common at the extremes of age), diabetes, and peripheral vascular disease [1.3.6]. Pharmacologic factors involve the properties of the infused drug; substances with a very high or low pH or high osmolality can irritate and damage the vein lining, increasing the likelihood of leaks [1.3.5].
Signs and Symptoms
The signs of blood extravasation are typically localized to the affected area and can range from mild to severe [1.3.3].
- Swelling and Edema: The accumulation of fluid and blood causes the tissue to swell and feel tight or taut [1.3.3].
- Pain and Discomfort: Patients often report sensations of pain, burning, or stinging at the site [1.3.2].
- Skin Discoloration: The area may appear red initially, followed by the characteristic black-and-blue of a bruise as the blood deoxygenates. Blanching (lightening of the skin) may also occur [1.3.3].
- Coolness of the Skin: The affected site may feel cool to the touch compared to surrounding tissue [1.3.2].
- Changes in IV Infusion: For extravasation during IV therapy, there may be a lack of blood return from the cannula or the infusion may slow down or stop [1.3.2, 1.3.7].
Extravasation vs. Infiltration vs. Hematoma
These terms are often related but have distinct meanings. Understanding their differences is key to proper diagnosis and management.
| Feature | Extravasation | Infiltration | Hematoma |
|---|---|---|---|
| Leaked Substance | A vesicant fluid (irritating/damaging), such as chemotherapy, or blood itself [1.4.4, 1.4.7]. | A non-vesicant fluid (non-irritating), such as saline or certain antibiotics [1.4.6]. | Blood that has clotted or is pooling outside of a blood vessel [1.4.1]. |
| Primary Cause | Often due to IV cannula displacement during infusion of a vesicant drug [1.4.4]. | Often due to IV cannula displacement during infusion of a non-vesicant fluid [1.4.2]. | Trauma or injury that ruptures a blood vessel, leading to a collection of blood [1.4.1]. |
| Key Consequence | Can cause tissue damage, blistering, necrosis (tissue death), and ulceration [1.4.7, 1.3.1]. | Causes swelling and discomfort but typically does not cause severe tissue damage [1.4.6, 1.6.4]. | A localized collection of blood, often called a bruise. Usually resolves on its own. |
Management and Treatment
The best approach to extravasation is prevention [1.7.1]. However, if it occurs, prompt action is critical to minimize damage.
Immediate Steps in a Clinical Setting
- Stop the Infusion: The first and most important step is to immediately stop the infusion of any fluid or medication [1.5.3].
- Aspirate the Drug: Before removing the cannula, a syringe is attached to try and aspirate any residual drug from the area [1.5.3].
- Remove the Cannula: The IV line is then removed [1.5.2].
- Elevate the Limb: Raising the affected arm or leg helps reduce swelling by encouraging fluid reabsorption [1.5.3, 1.5.2].
- Apply Compresses: Depending on the specific drug that extravasated, either cold or warm compresses are applied. Cold compresses cause vasoconstriction and limit the spread of the substance, while warm compresses promote vasodilation and help disperse it [1.5.3, 1.7.1].
Medical Interventions
In some cases, specific antidotes can be injected into the site to counteract the damaging effects of the extravasated drug [1.5.5]. For example, hyaluronidase can be used to help disperse certain drugs [1.5.5]. Severe cases with significant tissue damage or complications like compartment syndrome (a dangerous buildup of pressure) may require surgical intervention, such as a fasciotomy or debridement of necrotic tissue [1.2.7, 1.6.6].
Potential Complications
While many instances of blood extravasation are minor (like a simple bruise), severe cases can lead to serious complications:
- Tissue Necrosis: The death of tissue, which can lead to ulceration and require surgical removal [1.6.3].
- Compartment Syndrome: Severe swelling in a confined space can build up pressure and compromise blood flow, nerve function, and muscle health, potentially leading to permanent damage or even amputation [1.6.4, 1.2.7].
- Nerve and Tendon Damage: The leaked substance and resulting inflammation can damage nearby nerves and tendons, leading to chronic pain or loss of function [1.6.4].
- Infection: Broken skin from blistering or necrosis creates an entry point for bacteria [1.6.5].
Conclusion
What is meant by extravasation of blood is the leakage of blood from a vessel into the surrounding area, a phenomenon ranging from a simple bruise to a severe medical complication, particularly in the context of IV therapy [1.2.4, 1.2.6]. Prompt recognition of its symptoms—swelling, pain, and discoloration—is vital. While immediate steps like stopping an infusion and elevating the limb are crucial, prevention through proper IV insertion and monitoring techniques remains the most effective strategy to avoid potentially severe consequences like tissue necrosis and compartment syndrome [1.7.1, 1.6.4].
For more in-depth information on the management of extravasation, consider visiting the National Institutes of Health (NIH).
