Internal bleeding is bleeding

Bleeding

Bleeding, technically known as hemorrhaging or haemorrhaging is the loss of blood or blood escape from the circulatory system...

 occurring inside the body

Body

With regard to living things, a body is the physical body of an individual. "Body" often is used in connection with appearance, health issues and death...

. It can be a serious medical emergency

Medical emergency

A medical emergency is an injury or illness that is acute and poses an immediate risk to a person's life or long term health. These emergencies may require assistance from another person, who should ideally be suitably qualified to do so, although some of these emergencies can be dealt with by the...

 depending on where it occurs (e.g. brain, stomach, lungs), and can potentially cause death

Death

Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....

 and cardiac arrest

Cardiac arrest

Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...

 if proper medical treatment is not received quickly.
Internal bleeding can occur by traumatic injury

Trauma (medicine)

Trauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...

 such as high speed deceleration

Acceleration

In physics, acceleration is the rate of change of velocity with time. In one dimension, acceleration is the rate at which something speeds up or slows down. However, since velocity is a vector, acceleration describes the rate of change of both the magnitude and the direction of velocity. ...

 in an automobile accident, or by blood vessel

Blood vessel

The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...

 rupture from high blood pressure

Blood pressure

Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...

. Also, internal bleeding can be caused by hitting or running against a sharp object in that area.http://www.articleworld.org/index.php/Internal_bleeding Some diseases may also cause internal bleeding, such as the Filovirus Ebola

Ebola

Ebola virus disease is the name for the human disease which may be caused by any of the four known ebolaviruses. These four viruses are: Bundibugyo virus , Ebola virus , Sudan virus , and Taï Forest virus...

.