Varicose veins are veins that have been subjected to high pressure. Like a balloon, they expand in all directions creating the characteristic tortuosity frequently seen. Spider veins are simply small veins that have been subjected to the same pressure.
Do I have varicose veins?
High pressure in the veins is called venous hypertension. This usually occurs when too much blood collects in the veins. There are pathological conditions where the blood can't drain from the veins of the legs and back to the heart. This is a condition called chronic venous hypertension.
One of the signs of chronic venous hypertension can be varicose veins, where the high pressure and the veins blowup the vessels like the balloon. The high pressure can cause fluid to leak out of the vessels causing swelling or edema. This condition can also stimulate inflammation causing the legs to feel tired, heavy, painful, and can even cause cramps. When severe, the inflammation can cause a rash on the legs that can develop into ulcers. The inflammation can cause chronic scarring of the skin causing it to become rigid and contracted (called lipodermatosclerosis). It can also cause the skin to become darkly colored(hyperpigmentation). The inflammation can also cause damage to veins causing a blood clot to form. The veins can also stretch out to such an extent that they rupture, causing spontaneous bleeding. The symptoms are usually worse when a person stands or sits for a long time. Not everybody gets all of these signs or symptoms. Some people only have one or two.
Normally, the veins in the leg work like a bellows to pump blood from the legs back to the heart. With every step, the deep veins are compressed by the muscles to push the blood back to the heart. When the muscles relax the vacuum now present in the deep veins sucks the blood from the skin into the deep veins. With the next step the blood that has now accumulated in the deep veins goes back to the heart. The superficial veins that are in the skin simply collect blood. They have valves that are supposed to allow the blood to collect in little pockets under the skin. With each step, the blood in these pockets, drain into the deep veins, and then is pumped back to the heart.
Anything that prevents the blood from being pumped back to the heart can cause chronic venous hypertension. When the valves are broken in the veins, it allows blood to pool in the legs rather than being pumped out. When the superficial vein valves are broken, this can be corrected surgically. The purpose of surgical treatment (vein stripping, vein ablation, sclerotherapy) is to fix the leaks so that the veins can pump blood back to the heart like they are supposed to do.
There are other things that can cause these symptoms, however. It is the job of your doctor to identify these, as some of these could be signs of other more dangerous conditions. These include:
DVT (Deep Vein Thrombosis)
Vein compression by an external mass (such as a tumor)
Obstructive Sleep Apnea
Muscle Weakness or Paralysis
Lymphedema is a rare condition where lymphatic channels are blocked, leading to swelling. This can be congenital, but also can be caused by trauma to the channels, obstruction by masses such as tumors, or the effect of radiation. This is usually diagnosed by a test called lymphoscintigraphy.
Lipedema is another condition where a genetic distribution of body fat causes the legs to appear swollen. In this condition edema is not present.