Bleeding
Blood escaping from damaged vessels; hemostasis is critical.
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Bleeding, hemorrhage, or blood loss, occurs when blood escapes the circulatory system via damaged blood vessels. This can happen internally or externally, with external bleeding emerging through natural openings like the mouth, nose, ear, urethra, genitalia, or anus, or through a break in the skin.
A significant reduction in blood volume is termed hypovolemia, and death from excessive blood loss is known as exsanguination. A healthy individual can typically withstand a loss of 10–15% of total blood volume without serious medical issues; for context, a standard blood donation removes about 8–10% of a donor’s volume. The process of stopping or controlling bleeding is called hemostasis, a vital skill in both first aid and surgical settings.
Traumatic injury
Bleeding arises from either traumatic injury, an underlying medical condition, or a combination of both. Traumatic bleeding results from various wound types, including abrasions (superficial skin grazes), lacerations (irregular tears from blunt impact), incisions (clean cuts, such as from a scalpel), puncture wounds (from objects like nails or knives), contusions (bruises from blunt force), crush injuries (from prolonged extreme force), and ballistic trauma (from projectiles like firearms). The injury pattern, evaluation, and treatment depend on the mechanism.
Blunt trauma delivers energy over an area, often hiding significant injury beneath unbroken skin, while penetrating trauma follows the path of the object, requiring less energy for severe damage. Internal organs such as the liver, kidney, and spleen may bleed into the abdominal cavity, with blood loss being the only apparent sign. Bleeding from a bodily orifice can indicate internal bleeding but is not a reliable sole indicator.
Medical condition
Medical bleeding stems from underlying conditions rather than direct trauma. It results from three basic injury patterns: intravascular changes (e.g., altered blood pressure or clotting factors), intramural changes (e.g., aneurysms, dissections, or vasculitides within vessel walls), and extravascular changes (e.g., infections or tumors outside vessels). Conditions that impair normal hemostatic functions, known as bleeding diatheses, can make patients susceptible to hemorrhage.
Lore & Background
Bleeding arises from traumatic injury or underlying medical conditions. Traumatic causes include abrasions, lacerations, puncture wounds, contusions, crush injuries, and ballistic trauma.
Medical bleeding results from intravascular changes (e.g., high blood pressure, clotting factor deficiencies), intramural changes (e.g., aneurysms, arteriovenous malformations), or extravascular changes (e.g., infections, tumors). Common medical bleeding disorders include hemophilia A (Factor VIII deficiency), hemophilia B (Factor IX deficiency), and Von Willebrand disease. Medications such as NSAIDs (including aspirin and ibuprofen) and warfarin increase bleeding risk by impairing platelet function or clotting factor production.
Reader's Guide
Bleeding is a fundamental medical concept with broad clinical significance. The distinction between traumatic and medical causes guides diagnosis and treatment. Understanding hemostasis—the process of stopping bleeding—is essential for first aid and surgery. A healthy person can tolerate 10–15% blood loss, which informs transfusion thresholds.
Medical bleeding from anticoagulants like warfarin requires careful monitoring, especially during antibiotic use that reduces vitamin K production. Imaging advances, such as PET using 18F-labeled red blood cells, allow precise localization of intracerebral hemorrhages. The classification of bleeding by anatomical site (e.g., intracranial, gastrointestinal) and by cause (traumatic vs. medical) provides a framework for clinical management.
Did You Know?
- Aspirin irreversibly inhibits platelet activation, with effects lasting about ten days until platelets are replaced.
- Warfarin acts by inhibiting the production of Vitamin K in the gut, which is required for clotting factors II, VII, IX, and X.
- Infectious diseases such as Ebola, Marburg virus disease, and yellow fever can cause bleeding.
Frequently Asked Questions
What is Bleeding in the Cardiovascular & Blood series?
Bleeding describes blood leaking out of the circulatory system once a vessel is damaged, whether the loss stays internal or spills externally. If left unchecked, severe loss can trigger hypovolemia and ultimately kill through exsanguination.
What causes Bleeding?
Bleeding can result from traumatic injury or from an underlying condition involving intravascular, intramural, or extravascular changes. Specific triggers include clotting disorders like hemophilia and Von Willebrand disease, medications such as NSAIDs or warfarin, and viral infections including Ebola, Marburg virus, and yellow fever.
How is Bleeding controlled and imaged?
Hemostasis—the process of stopping a bleed—is a cornerstone of both first aid and surgical practice. On the diagnostic side, dioxaborolane chemistry enables radioactive fluoride-18 labeling of red blood cells for PET imaging of intracerebral hemorrhages.
More in Cardiovascular & Blood
Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Bleeding (CC BY-SA 4.0).
- Word definitions: the Codexery glossary, each quoted from its Wikipedia article.
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