Bleeding, hemorrhage, or blood loss, is blood escaping from the circulatory system from damaged blood vessels.

It can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vagina or anus, or through a puncture in the skin. 

Major bleeding can lead to hypovolemia, a massive decrease in blood volume, and death by excessive loss of blood is referred to as exsanguination.

Typically, a healthy person can endure a loss of 10–15% of the total blood volume without serious medical difficulties.

Blood donation typically takes 8–10% of the donor’s blood volume.

Melena – upper gastrointestinal bleeding

Hematochezia – lower gastrointestinal bleeding, or brisk upper gastrointestinal bleeding


Ruptured aneurysm

Aortic transection

Iatrogenic injury

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

Traumatic bleeding is caused by some type of injury. 

There are different types of wounds which may cause traumatic bleeding:






Puncture Wound

Contusion – Also known as a bruise, this is a blunt trauma damaging tissue under the surface of the skin.

Crushing Injuries – Caused by a great or extreme amount of force applied over a period of time. 

Ballistic Trauma 

The pattern of injury, evaluation and treatment will varies with the type of injury. 

Blunt trauma causes injury via a shock effect; delivering energy over an area, are often not straight and unbroken skin may hide significant injury. 

Penetrating trauma follows the course of the injurious device. 

Any body organ, including bone and brain, can be injured and bleed. 

Bleeding may not be readily apparent, as with internal organs such as the liver, kidney and spleen that 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. 

Medical bleeding denotes hemorrhage as a result of an underlying medical condition not directly due to trauma.  

Blood can escape from blood vessels as a result of 3 basic patterns of injury:

Intravascular changes – changes of the blood within vessels such as ↑ hypertension blood pressure, or decreased clotting factors. 

Intramural changes of the walls of blood vessels-aneurysms, dissections, AVMs, vasculitides.

Extravascular changes – changes arising outside blood vessels-H pylori infection, brain abscess, brain tumor

Some medical conditions that affect the normal hemostatic (bleeding-control) functions of the body can make patients susceptible to bleeding. 

Such conditions either are, or cause, bleeding diatheses. 

Hemostasis involves the hemostatic system including  platelets and the coagulation system.

Platelets 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, in about ten days.

Other NSAIDs, such as ibuprofen and related drugs, are reversible and therefore, the effect on platelets is not as long-lived.

Deficiencies of coagulation factors are associated with clinical bleeding. 

Deficiency of Factor VIII causes classic hemophilia A while deficiencies of Factor IX cause hemophilia B.

Antibodies to Factor VIII can also inactivate the Factor VII and precipitate bleeding that is very difficult to control. 

Von Willebrand disease 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.

 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. 

Gut  bacteria make vitamin K and are killed by antibiotics, decreasing 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.

Hemorrhaging is broken down into four classes by the American College of Surgeons.

Class I Hemorrhage involves up to 15% of blood volume. 

There is typically no change in vital signs and fluid resuscitation is not usually necessary.

Class II Hemorrhage involves 15-30% of total blood volume. 

A patient is often tachycardic with a reduction in the difference between the systolic and diastolic blood pressures. 

Volume resuscitation with crystalloids is all that is typically required. 

Blood transfusion is not usually required.

Class III Hemorrhage involves loss of 30-40% of circulating blood volume. 

The patient’s blood pressure drops, the heart rate increases, peripheral hypoperfusion with diminished capillary refill occurs, and the mental status deteriorates. 

Fluid resuscitation with crystalloid and blood transfusion are usually necessary.

Class IV Hemorrhage involves loss of >40% of circulating blood volume. 

The limit of the body’s compensation is reached and aggressive resuscitation is required to prevent death.

Massive hemorrhage: no universally accepted definition of massive hemorrhage exists.

(i) blood loss exceeding circulating blood volume within a 24-hour 

(ii) blood loss of 50% of circulating blood volume within a 3-hour period, 

(iii) blood loss exceeding 150 ml/min,

 (iv) blood loss that necessitates plasma and platelet transfusion.

The World Health Organization standardized grading scale to measure the severity of bleeding.

Grade 0 no bleeding;

Grade 1 petechial bleeding;

Grade 2 mild blood loss (clinically significant);

Grade 3 gross blood loss, requires transfusion (severe);

Grade 4 debilitating blood loss, retinal or cerebral associated with fatality

Acute bleeding from an injury to the skin is often treated by the application of direct pressure.

For severely injured patients, tourniquets are helpful in preventing complications of shock.

Anticoagulant medications may need to be discontinued and possibly reversed in patients with clinically significant bleeding.

Patients that have lost excessive amounts of blood may require a blood transfusion.

Skin glue, is sometimes used instead of using traditional stitches used for small wounds that need to be closed at the skin level.

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