Last updated
Other namesHemorrhaging, hemorrhaging
Bleeding finger.jpg
A bleeding wound in the finger
Specialty Emergency medicine, hematology

Bleeding, also known as a hemorrhage, haemorrhage, or simply blood loss, is blood escaping from the circulatory system from damaged blood vessels. [1] Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vagina or anus, or through a wound in the skin. Hypovolemia is a massive decrease in blood volume, and death by excessive loss of blood is referred to as exsanguination. [2] Typically, a healthy person can endure a loss of 10–15% of the total blood volume without serious medical difficulties (by comparison, blood donation typically takes 8–10% of the donor's blood volume). [3] The stopping or controlling of bleeding is called hemostasis and is an important part of both first aid and surgery. The use of cyanoacrylate glue to prevent bleeding and seal battle wounds was designed and first used in the Vietnam War. Today many medical treatments use a medical version of "super glue" instead of using traditional stitches used for small wounds that need to be closed at the skin level.



A subconjunctival hemorrhage is a common and relatively minor post-LASIK complication. Eye hemorrhage.jpg
A subconjunctival hemorrhage is a common and relatively minor post-LASIK complication.
The endoscopic image of a type of stomach cancer known as linitis plastica. The leather bottle-like appearance can also cause bleeding as can be seen in this image. Linitis plastica 2.jpg
The endoscopic image of a type of stomach cancer known as linitis plastica. The leather bottle-like appearance can also cause bleeding as can be seen in this image.
Micrograph showing abundant hemosiderin-laden alveolar macrophages (dark brown), as seen in a pulmonary hemorrhage. H&E stain. Pulmonary haemorrhage - high mag.jpg
Micrograph showing abundant hemosiderin-laden alveolar macrophages (dark brown), as seen in a pulmonary hemorrhage. H&E stain.

Blood loss

Hemorrhaging is broken down into four classes by the American College of Surgeons' advanced trauma life support (ATLS). [4]

This system is basically the same as used in the staging of hypovolemic shock.

Individuals in excellent physical and cardiovascular shape may have more effective compensatory mechanisms before experiencing cardiovascular collapse. These patients may look deceptively stable, with minimal derangements in vital signs, while having poor peripheral perfusion. Elderly patients or those with chronic medical conditions may have less tolerance to blood loss, less ability to compensate, and may take medications such as betablockers that can potentially blunt the cardiovascular response. Care must be taken in the assessment.

Massive hemorrhage

Although there is no universally accepted definition of massive hemorrhage, the following can be used to identify the condition: "(i) blood loss exceeding circulating blood volume within a 24-hour period, (ii) blood loss of 50% of circulating blood volume within a 3-hour period, (iii) blood loss exceeding 150 ml/min, or (iv) blood loss that necessitates plasma and platelet transfusion." [5]

World Health Organization

The World Health Organization made a standardized grading scale to measure the severity of bleeding. [6]

Grade 0no bleeding
Grade 1 petechial bleeding;
Grade 2mild blood loss (clinically significant);
Grade 3gross blood loss, requires transfusion (severe);
Grade 4debilitating blood loss, retinal or cerebral associated with fatality



Bleeding arises due to either traumatic injury, underlying medical condition, or a combination.

Traumatic injury

Traumatic bleeding is caused by some type of injury. There are different types of wounds which may cause traumatic bleeding. These include:

The pattern of injury, evaluation and treatment will vary with the mechanism of the injury. Blunt trauma causes injury via a shock effect; delivering energy over an area. Wounds are often not straight and unbroken skin may hide significant injury. Penetrating trauma follows the course of the injurious device. As the energy is applied in a more focused fashion, it requires less energy to cause significant injury. Any body organ, including bone and brain, can be injured and bleed. Bleeding may not be readily apparent; internal organs such as the liver, kidney and spleen may bleed into the abdominal cavity. The only apparent signs may come with blood loss. Bleeding from a bodily orifice, such as the rectum, nose, or ears may signal internal bleeding, but cannot be relied upon. Bleeding from a medical procedure also falls into this category.

Medical condition

"Medical bleeding" denotes hemorrhage as a result of an underlying medical condition (i.e. causes of bleeding that are not directly due to trauma). Blood can escape from blood vessels as a result of 3 basic patterns of injury:

The underlying scientific basis for blood clotting and hemostasis is discussed in detail in the articles, coagulation, hemostasis and related articles. The discussion here is limited to the common practical aspects of blood clot formation which manifest as bleeding.

Some medical conditions can also make patients susceptible to bleeding. These are conditions that affect the normal hemostatic (bleeding-control) functions of the body. Such conditions either are, or cause, bleeding diatheses. Hemostasis involves several components. The main components of the hemostatic system include platelets and the coagulation system.

Platelets are small blood components that form a plug in the blood vessel wall that stops bleeding. Platelets also produce a variety of substances that stimulate the production of a blood clot. One of the most common causes of increased bleeding risk is exposure to nonsteroidal anti-inflammatory drugs (NSAIDs). The prototype for these drugs is aspirin, which inhibits the production of thromboxane. NSAIDs inhibit the activation of platelets, and thereby increase the risk of bleeding. The effect of aspirin is irreversible; therefore, the inhibitory effect of aspirin is present until the platelets have been replaced (about ten days). Other NSAIDs, such as "ibuprofen" (Motrin) and related drugs, are reversible and therefore, the effect on platelets is not as long-lived.

There are several named coagulation factors that interact in a complex way to form blood clots, as discussed in the article on coagulation. Deficiencies of coagulation factors are associated with clinical bleeding. For instance, deficiency of Factor VIII causes classic hemophilia A while deficiencies of Factor IX cause "Christmas disease"(hemophilia B). Antibodies to Factor VIII can also inactivate the Factor VII and precipitate bleeding that is very difficult to control. This is a rare condition that is most likely to occur in older patients and in those with autoimmune diseases. Another common bleeding disorder is Von Willebrand disease. It is caused by a deficiency or abnormal function of the "Von Willebrand" factor, which is involved in platelet activation. Deficiencies in other factors, such as factor XIII or factor VII are occasionally seen, but may not be associated with severe bleeding and are not as commonly diagnosed.

In addition to NSAID-related bleeding, another common cause of bleeding is that related to the medication, warfarin ("Coumadin" and others). This medication needs to be closely monitored as the bleeding risk can be markedly increased by interactions with other medications. Warfarin acts by inhibiting the production of Vitamin K in the gut. Vitamin K is required for the production of the clotting factors, II, VII, IX, and X in the liver. One of the most common causes of warfarin-related bleeding is taking antibiotics. The gut bacteria make vitamin K and are killed by antibiotics. This decreases vitamin K levels and therefore the production of these clotting factors.

Deficiencies of platelet function may require platelet transfusion while deficiencies of clotting factors may require transfusion of either fresh frozen plasma or specific clotting factors, such as Factor VIII for patients with hemophilia.


Infectious diseases such as Ebola, Marburg virus disease and yellow fever can cause bleeding.


Dioxaborolane chemistry enables radioactive fluoride (18F) labeling of red blood cells, which allows for positron emission tomography (PET) imaging of intracerebral hemorrhages. [8]


Acute bleeding from an injury to the skin is often treated by the application of direct pressure. [9] For severely injured patients, tourniquets are helpful in preventing complications of shock. [10] Anticoagulant medications may need to be discontinued and possibly reversed in patients with clinically significant bleeding. [11] Patients that have lost excessive amounts of blood may require a blood transfusion. [12]


The word "Haemorrhage" (or hæmorrhage; using the æ ligature) comes from Latin haemorrhagia, from Ancient Greek αἱμορραγία (haimorrhagía, "a violent bleeding"), from αἱμορραγής (haimorrhagḗs, "bleeding violently"), from αἷμα (haîma, "blood") + -ραγία (-ragía), from ῥηγνύναι (rhēgnúnai, "to break, burst"). [13]

See also

Related Research Articles


A thrombus, colloquially called a blood clot, is the final product of the blood coagulation step in hemostasis. There are two components to a thrombus: aggregated platelets and red blood cells that form a plug, and a mesh of cross-linked fibrin protein. The substance making up a thrombus is sometimes called cruor. A thrombus is a healthy response to injury intended to prevent bleeding, but can be harmful in thrombosis, when clots obstruct blood flow through healthy blood vessels.

Platelet Component of blood aiding in coagulation

Platelets, also called thrombocytes, are a component of blood whose function is to react to bleeding from blood vessel injury by clumping, thereby initiating a blood clot. Platelets have no cell nucleus; they are fragments of cytoplasm that are derived from the megakaryocytes of the bone marrow, which then enter the circulation. Circulating unactivated platelets are biconvex discoid (lens-shaped) structures, 2–3 µm in greatest diameter. Activated platelets have cell membrane projections covering their surface. Platelets are found only in mammals, whereas in other vertebrates, thrombocytes circulate as intact mononuclear cells.

Haemophilia A

Haemophilia A is a genetic deficiency in clotting factor VIII, which causes increased bleeding and usually affects males. In the majority of cases it is inherited as an X-linked recessive trait, though there are cases which arise from spontaneous mutations.

Haemophilia B Genetic X-linked recessive bleeding disorder

Haemophilia B, also spelled Hemophilia B is a blood clotting disorder causing easy bruising and bleeding due to an inherited mutation of the gene for factor IX, and resulting in a deficiency of factor IX. It is less common than factor VIII deficiency.

Coagulation Process by which blood changes from a liquid to a gel, forming a blood clot

Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism of coagulation involves activation, adhesion and aggregation of platelets, as well as deposition and maturation of fibrin.

Disseminated intravascular coagulation

Disseminated intravascular coagulation (DIC) is a condition in which blood clots form throughout the body, blocking small blood vessels. Symptoms may include chest pain, shortness of breath, leg pain, problems speaking, or problems moving parts of the body. As clotting factors and platelets are used up, bleeding may occur. This may include blood in the urine, blood in the stool, or bleeding into the skin. Complications may include organ failure.

Von Willebrand disease

Von Willebrand disease (VWD) is the most common hereditary blood-clotting disorder in humans. An acquired form can sometimes result from other medical conditions. It arises from a deficiency in the quality or quantity of von Willebrand factor (VWF), a multimeric protein that is required for platelet adhesion. It is known to affect several breeds of dogs as well as humans. The three forms of VWD are hereditary, acquired, and pseudo or platelet type. The three types of hereditary VWD are VWD type 1, VWD type 2, and VWD type 3. Type 2 contains various subtypes. Platelet type VWD is also an inherited condition.

Hypovolemia, also known as volume depletion or volume contraction, is a state of abnormally low extracellular fluid in the body. This may be due to either a loss of both salt and water or a decrease in blood volume. Hypovolemia refers to the loss of extracellular fluid and should not be confused with dehydration.

Hemostasis or haemostasis is a process to prevent and stop bleeding, meaning to keep blood within a damaged blood vessel. It is the first stage of wound healing. This involves coagulation, blood changing from a liquid to a gel. Intact blood vessels are central to moderating blood's tendency to form clots. The endothelial cells of intact vessels prevent blood clotting with a heparin-like molecule and thrombomodulin and prevent platelet aggregation with nitric oxide and prostacyclin. When endothelial injury occurs, the endothelial cells stop secretion of coagulation and aggregation inhibitors and instead secrete von Willebrand factor, which initiate the maintenance of hemostasis after injury. Hemostasis has three major steps: 1) vasoconstriction, 2) temporary blockage of a break by a platelet plug, and 3) blood coagulation, or formation of a fibrin clot. These processes seal the hole until tissues are repaired.

Hematemesis is the vomiting of blood. The source is generally the upper gastrointestinal tract, typically above the suspensory muscle of duodenum. Patients can easily confuse it with hemoptysis, although the latter is more common. Hematemesis "is always an important sign".

Internal bleeding

Internal bleeding is a loss of blood from a blood vessel that collects inside the body. Internal bleeding is usually not visible from the outside. It is a serious medical emergency but the extent of severity depends on bleeding rate and location of the bleeding. Severe internal bleeding into the chest, abdomen, retroperitoneal space, pelvis, and thighs can cause hemorrhagic shock or death if proper medical treatment is not received quickly. Internal bleeding is a medical emergency and should be treated immediately by medical professionals.

Bruise Type of hematoma of tissue

A bruise, also known as a contusion, is a type of hematoma of tissue, the most common cause being capillaries damaged by trauma, causing localized bleeding that extravasates into the surrounding interstitial tissues. Most bruises are not very deep under the skin so that the bleeding causes a visible discoloration. The bruise then remains visible until the blood is either absorbed by tissues or cleared by immune system action. Bruises, which do not blanch under pressure, can involve capillaries at the level of skin, subcutaneous tissue, muscle, or bone. Bruises are not to be confused with other similar-looking lesions. These lesions include petechia, purpura, and ecchymosis.

In medicine (hematology), bleeding diathesis is an unusual susceptibility to bleed (hemorrhage) mostly due to hypocoagulability, in turn caused by a coagulopathy. Therefore, this may result in the reduction of platelets being produced and leads to excessive bleeding. Several types of coagulopathy are distinguished, ranging from mild to lethal. Coagulopathy can be caused by thinning of the skin, such that the skin is weakened and is bruised easily and frequently without any trauma or injury to the body. Also, coagulopathy can be contributed by impaired wound healing or impaired clot formation.

Glanzmanns thrombasthenia

Glanzmann's thrombasthenia is an abnormality of the platelets. It is an extremely rare coagulopathy, in which the platelets contain defective or low levels of glycoprotein IIb/IIIa (GpIIb/IIIa), which is a receptor for fibrinogen. As a result, no fibrinogen bridging of platelets to other platelets can occur, and the bleeding time is significantly prolonged.

Hypovolemic shock is a medical emergency and an advanced form of hypovolemia due to insufficient amounts of blood and/or fluid inside the human body to let the heart pump enough blood to the body. More specifically, hypovolemic shock occurs when there is decreased intravascular volume to the point of cardiovascular compromise. The hypovolemic shock could be due to severe dehydration through a variety of mechanisms or from blood loss.

Coagulopathy Condition in which the blood’s ability to coagulate (form clots) is impaired

Coagulopathy is a condition in which the blood's ability to coagulate is impaired. This condition can cause a tendency toward prolonged or excessive bleeding, which may occur spontaneously or following an injury or medical and dental procedures. Of note, coagulopathies are sometimes erroneously referred to as "clotting disorders"; a clotting disorder is a predisposition to clot formation (thrombus), also known as a hypercoagulable state or thrombophilia.

An antihemorrhagic (antihæmorrhagic) agent is a substance that promotes hemostasis. It may also be known as a hemostatic agent.

Thromboelastography (TEG) is a method of testing the efficiency of blood coagulation. It is a test mainly used in surgery and anesthesiology, although increasingly used in resuscitations in Emergency Departments, intensive care units, and labor and delivery suites. More common tests of blood coagulation include prothrombin time (PT) and partial thromboplastin time (aPTT) which measure coagulation factor function, but TEG also can assess platelet function, clot strength, and fibrinolysis which these other tests cannot.


Hypoprothrombinemia is a rare blood disorder in which a deficiency in immunoreactive prothrombin, produced in the liver, results in an impaired blood clotting reaction, leading to an increased physiological risk for spontaneous bleeding. This condition can be observed in the gastrointestinal system, cranial vault, and superficial integumentary system, affecting both the male and female population. Prothrombin is a critical protein that is involved in the process of hemostasis, as well as illustrating procoagulant activities. This condition is characterized as an autosomal recessive inheritance congenital coagulation disorder affecting 1 per 2,000,000 of the population, worldwide, but is also attributed as acquired.

Permissive hypotension or hypotensive resuscitation is the use of restrictive fluid therapy, specifically in the trauma patient, that increases systemic blood pressure without reaching normotension. The goal blood pressure for these patients is a mean arterial pressure of 40-50mmHg or a systolic blood pressure less than or equal to 80. This goes along with certain clinical criteria. Following traumatic injury some patients experience hypotension that is usually due to blood loss (hemorrhage) but can be due to other causes as well. In the past, physicians were very aggressive with fluid resuscitation to try to bring the blood pressure to normal values. Recent studies have found that there is some benefit to allowing specific patients to experience some degree of hypotension in certain settings. This concept does not exclude therapy by means of i.v. fluid, inotropes or vasopressors, the only restriction is to avoid completely normalizing blood pressure in a context where blood loss may be enhanced. When a person starts to bleed the body starts a natural coagulation process that eventually stops the bleed. Issues with fluid resuscitation without control of bleeding is thought to be secondary to dislodgement of the thrombus that is helping to control further bleeding. Thrombus dislodgement was found to occur at a systolic pressure greater than 80mm Hg. In addition, fluid resuscitation will dilute coagulation factors that help form and stabilize a clot, hence making it harder for the body to use its natural mechanisms to stop the bleeding. These factors are aggravated by hypothermia.


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