There are several reasons your fingers may turn blue. The most simple diagnosis may be bruising. Or it could be cyanosis, which manifests as blue colouration of the skin due to the lack of oxygen in the bloodstream. Cyanosis can be caused by anything from frostbite to more complex diseases. If parts of the body do not receive enough oxygen, the tissue will become necrotic, meaning the cells will die.
Bruising is one of the most common conditions where the fingers may turn blue. When there is damage to the capillaries, the blood will rush into the tissue to try to heal it, causing it to darken.
Congenital Heart Defects
If a baby is born with a congenital heart defect, there usually is not enough oxygen and blood flow throughout the body. One of the first symptoms of lack of oxygen is blueness in the fingers.
Shaken Baby Syndrome
If a baby is brought into the emergency room unconscious and the body is blue in colour, including the fingers, doctors will first consider shaken baby syndrome. This syndrome can easily cause brain damage.
Circulatory shock is a dangerous condition where insufficient blood flow reaches the body tissues. It can cause multiple organ failure and is one of the most common causes of death. If you are in shock, your fingertips will appear bluish, your skin will be clammy, you may be confused or unconscious.
Raynaud's syndrome is a condition thought to be caused by the sympathetic nervous system that causes the fingers to either turn white or blue due to a lack of blood flow. It usually comes on suddenly, and the hands and fingers need to be placed in warm water and rubbed to get blood flowing back to the fingers. Smoking and caffeine can worsen the syndrome for patients.
If a blood clot slows down the flow of blood to the fingers, they will turn blue due to lack of oxygen to the tissues. If a clot blocks blood flow to an artery in the heart or brain, it could cause a heart attack or stroke.