Heavy internal bleeding may occur in the abdominal cavity, chest cavity, digestive tract, or tissues surrounding large bones, such as the thighbone (femur) and pelvis, that are broken.
Initially, internal bleeding may cause no symptoms, although an injured organ that is bleeding may be painful. However, the person may be distracted from this pain by other injuries or may be unable to express pain because of confusion, drowsiness, or unconsciousness. Eventually, internal bleeding usually becomes apparent. For example, blood in the digestive tract may cause vomiting of blood or passage of bloody or black stool. Extensive blood loss causes low blood pressure, making the person feel weak and light-headed. The person may faint when standing or even sitting and, if blood pressure is very low, lose consciousness.
A lay person cannot stop internal bleeding. If extensive bleeding causes light-headedness or symptoms of shock (see Shock), the person should be laid down and the legs elevated. Medical assistance should be summoned as quickly as possible.