Haemorrhage just means the escape of blood from any artery or vein. The bleeding may occur externally via a wound or an injured blood vessel near the surface, as in a nosebleed. In other cases bleeding may be into the tissues, causing bruising, as in a ‘black eye’. Bleeding may also occur between tissues or into a natural internal space, causing a larger blood collection called a haematoma.Large blood collections can cause harm or danger by their effect on the structures next to them. Bleeding inside the skull is particularly dangerous because it compresses the brain. A person who suffers a head injury and recovers consciousness, but who later lapses again into unconsciousness, may die. This is because almost certainly a growing haematoma is compressing the brain and will eventually destroy the vital centres.

Bleeding into the brain is also very dangerous. This may occur suddenly from rupture of an internal artery, or from an artery on the surface of the brain, often on the underside. Such bleeding causes a stroke.

Bleeding into the bowel causes jet-black stools, if the blood is released high in the intestine. Blood released into the lower bowel has a more normal appearance.

Bleeding into the potential space between the lung and the chest wall forces the lung on that side to collapse. This is called a haemothorax.

Causes

Haemorrhage occurs from:

• Injury of any kind to blood vessels
• External disease processes that cause an opening in a blood vessel
• Weakness in the wall of an artery so that it bulges (Aneurysm) and bursts
• Excessively high blood pressure that bursts normal or diseased blood vessels
• Swelling and distortion of a vein (varicosity)

The main arterial disease, atherosclerosis, often weakens arteries, leading to local ballooning and possible rupture. Sometimes the wall of an atherosclerotic artery will split, with blood passing between the layers.

Varicose viens in the legs may bleed seriously. More serious varicose veins occur at the bottom end of the gullet when cirrhosis of the liver forces blood from the intestine (which normally passes through the liver) to find an alternative pathway back to the heart. Gullet varicose veins (oesophageal varices) can cause dangerous bleeding.

Treatment

Haemorrhage is controlled initially by direct pressure, then by tying off the bleeding vessel. Shock is treated by blood transfusion or fluid infusion.