What are the signs of blood clots in the leg?

What are the signs of blood clots in the leg?

Signs of blood clots in the leg depend on whether the clot is in the artery or the vein. Arteries are blood vessels carrying oxygenated blood to the legs. Veins return blood with less oxygen back to the heart and lungs for oxygen enrichment.

Arteries have bright red colour because of the higher oxygen content of the blood in them. They have thick muscular walls as blood travels at higher pressure in them. Heart pumps the blood into them with each heartbeat.

Veins have a bluish colour as they contain blood with lesser oxygen content, returning to the heart and lungs for oxygen enrichment. Blood moves in them when the muscles contract over them, that is when we walk about or move our limbs.

When the artery is blocked, it produces pain, pallor, coldness of the leg, loss of sensation and power of movement (paralysis). If the occlusion of the artery persists for a long period, the limb will become black with death of cells, called as gangrene.

This occurs when the block occurs abruptly. In a gradually progressing obstruction, one first notes pain in the legs on walking (claudication). This pain subsides with rest and recurs on walking. Distance at which pain starts is an important indication of the severity of obstruction. More severe obstructions produce pain on walking for a short while.

Claudication distance is the distance at which one has to stop walking due to the pain. Claudication distance can improve in the long run when the leg develops its own collateral blood vessels or natural bypass. This process can also be enhanced by a graduated exercise program and medications.

Clots in the veins can occur when one is bedridden after a major illness, operation or fracture. This can be prevented to some extent by active or passive movements of the legs while taking rest. Medications can also help to prevent clot formation in the veins.

Clots in the vein obstruct return of the blood from the legs to the heart and lungs for oxygenation. The legs will become swollen and painful, with a bluish red colour.

Clots in the veins can migrate to the lungs and produce pulmonary embolism, a potentially fatal condition if it is massive. Clots travel up from the blood vessels of the legs, through blood vessels of the tummy into the heart and then the lungs.

Clots blocking the blood vessels of the lungs produce breathlessness, fall in blood oxygen levels, fall in blood pressure and sometimes chest pain. This needs emergency treatment.