Extravasation is the escape of a fluid from its contained space into the surrounding area, particularly the release of blood or blood cells from vessels. In the context of inflammation, it describes the movement of white blood cells through the capillary walls and into the surrounding tissues, a process known as leukocyte extravasation or diapedesis. In the case of cancer metastasis, it refers to the exiting of cancer cells from the capillaries and their penetration into other tissues, potentially giving rise to secondary tumors. In IV infusions, extravasation is the leakage of intravenously (IV) infused, and potentially damaging, medications into the extravascular tissue around the site of infusion. This term is frequently employed within a medical context.
The term "extravasation" is based on Latin ("extra", which refers to being outside something and "vas" refers to vessel).
Extravasation in IV context
In IV context, it refers to the unintended escape of intravenously administered medications, which may have the potential to cause harm, into the surrounding tissue rather than remaining within the blood vessels. This escape can be attributed to fragile veins in elderly patients, prior puncture sites, or improper placement of venous access devices. When the leakage does not pose a significant risk, it is termed infiltration.
Extravasation of medication during intravenous therapy is an adverse event of the treatment process. Depending on the specific medication, the extent of exposure, and the location of extravasation, it has the potential to result in severe injuries, including tissue necrosis. Milder consequences of extravasation may manifest as irritation, characterized by symptoms such as pain and inflammation, along with clinical signs such as warmth, redness (erythema), or tenderness.
Extravasation of infusates
Refers to the escape of substances infused into the blood vessels into the subcutaneous tissue. This leakage, particularly of high-osmolarity solutions or chemotherapy agents, can lead to substantial tissue damage and pose significant complications.
Extravasation of irrigation fluid
Refers to the unintended movement of irrigation solutions (e.g., saline) introduced into the human body. This can occur during various endoscopic surgical procedures, including minimally invasive orthopedic surgery like arthroscopy, TURP (trans-urethral resection of the prostate), and TCRE (trans-cervical resection of the endometrium).
Extravasation of urine
Extravasation of urine is a term used to describe a situation in which a disruption in the urethra results in the accumulation of urine in other cavities, such as the scrotum or the penis in males. This condition is occasionally linked to the presence of a calculus (stone).
Leukocyte extravasation
Leukocyte extravasation, often referred to as the leukocyte adhesion cascade or diapedesis (the passage of cells through the intact vessel wall), entails the migration of leukocytes from the bloodstream to the site of tissue injury or infection. This critical step is integral to the innate immune response, where non-specific leukocytes are recruited. Monocytes also employ this mechanism as they transform into macrophages, even in the absence of infection or tissue damage during their developmental process.
Extravasation in cell context
Cell extravasation or Angiopellosis, is the process by which cells exit the circulatory system and infiltrate the surrounding tissue. It's important to note that this mechanism primarily pertains to non-leukocytic cells, as white blood cells (leukocytes) utilize diapedesis to leave the bloodstream. The concept of angiopellosis was first elucidated through research into how stem cells reach damaged tissues when introduced into the circulatory system.
This phenomenon has revealed that circulating tumor cells (CTCs) possess the capability to exit blood vessels through angiopellosis, particularly during the metastatic process. Angiopellosis involves the recognition of cell-to-cell interactions with the blood vessel wall (endothelial cells) and the active modification of the blood vessel structure to facilitate the exit of the cell.