« Doctor, my legs are swollen! » It is not rare that we hear this sentence.

There are different levels of swelling. Most people who work standing all day can see the linings of their socks on their skin when they take them off in the evening.


Rest assured. The presence of a small marking is normal. The degree of the swelling varies greatly. However, having difficulty putting on your shoes is not normal.


Worried? You must talk about it

If you are worried about swollen legs, speak to your doctor about it.

There are many causes to this problem.

Your doctor can find the reason for yours.



Possible causes

The most frequent cause of swollen legs, at times of different sizes, is related to a malfunction with the veins of your legs, called venous insufficiency.

The other causes may be consequences of blood diseases, problems with kidneys or liver and certain intestinal sicknesses, to name a few.

The heart may also be the origin of the problem. In this case, the leg swelling is one of many symptoms present, like extreme fatigue that forces you to change routine activities, being out of breath and regularly having difficulty sleeping.


Review of how circulation works

The veins are vessels, hoses that bring used blood to the heart. It is important to know that blood makes it to the legs through the arteries. These arteries divide themselves into smaller arteries, then into arterioles, to finally deliver the oxygen to the muscles and other structures of the leg.


Everything takes place in the capillaries

The oxygen and nutriments are delivered through the systemic capillaries like everywhere else in the human body.

The systematic capillaries are the junction points between the arteries and the veins of the human body. They are microscopic vessels in which the blood cells travel one by one.


What is a capillary?

The capillaries are like drains with leaks covered with a thin membrane that prevent the proteins and the blood cells to leave, but that allow the blood fluids to escape and/or the blood circulation to resume.




It is a bit like if your sink in your kitchen. The water comes through pipes. You use it and it leaves through the drainage system. In the pipes or in the drain, everything is waterproof.




Stability point

Normally, there must be stability between what comes out and what goes in. There isn’t any accumulation of liquid in the capillaries. But, where does this equity in the liquid that exits the capillaries and the fluid that returns to them?


Human body cells are in water

It is important to know that the cells of the body must float in a liquid to correctly function and to allow the oxygen (O2) to travel to the cells and the carbon dioxide (CO2) to make it to the capillaries, then to the veins of the human body.



Three factors control the water

Three factors influence the water entering and exiting the capillary: one tries to keep it inside and the other allows it to escape and the third one is the pressure in the capillaries.


“Oncotic” factor

Let’s call the first factor, the oncotic factor or oncotic pressure. The "in" factor!

Water retention in the capillary is controlled by the blood cells and the proteins in the blood that cannot cross the capillary membrane and therefore stay inside.



“Osmotic” factor

The second factor that influences the entrance and exit of the water in the capillaries is the osmotic factor or pressure.

The term osmotic comes from the word “osmose”, meaning the freeway for water to neutralize the concentrations on the interior and on the exterior of the capillaries.

This way, the cells float without overflowing.



The veins in the legs are special

The blood exits the capillaries, pushed by the pressure made by the heart. This pushed is transmitted to the veins to carry the used blood to the heart. Gravity forces the weight of the blood to descend when standing.

To solve this problem, the veins have small valves that prevent the blood to go back down to the bottom of your legs. In other words, the valves work in the veins to maintain the blood in place until the next push made by the heart.

The contractions of the calf’s muscles also help circulate the blood towards the top of the leg.


The veins in the legs can dilate

With time, certain factors cause dilatation in the veins of the legs and from these, varicose veins are formed:

·        Pregnancies

·        People who are always standing

·        …

The dilatation of the veins alters the quality of the sealing of the valves in the veins, which causes the blood to head back down the legs, leading to stagnation.

The accumulation of the blood in the dilated veins increases the weight of the blood, which in turn causes an increase in the pressure in these veins.



This stagnation affects the capillaries where the liquid leaves the place where the cells are floating… overflow!






“Blood pressure in the capillaries” factor

This leads us to the 3rd factor that regulates the entrance and exiting of the liquid in the systemic capillaries.

The contraction of the heart pushes the blood throughout the human body, otherwise known as blood pressure. A normal blood pressure at the systemic capillary level is the equivalent of a few millimeters of mercury.

An increase in the pressure in the veins, as described here, is automatically transmitted to the capillaries. It will have the effect of creating blood congestion in these capillaries.


An ice jam in the river

Let us take the example of an ice jam in a river.

The water rises at the jam, finds its way out of its bed and floods the surroundings.




The water floods the surroundings

In legs, the stagnation created by the defective work of the veins and their small interior valves causes the water to accumulate in the cell “tub”, like the river that floods the land.


Vicious circle

Once the veins are dilated and their small valves cannot do their job of preventing the blood to go to the bottom of the legs, the vicious circle begins.

The higher the distension, the more the gravity effect is pronounced and the most important becomes the blood columns. The pressure in these stagnant veins increases and there are repercussions in the capillaries. It’s the venous “jam”.


Worse at the end of the day

People suffering from venous insufficiency in the legs get up in the morning with minor swelling, if any. The problem appears as the day progresses and is more evident in the evening. In the case of severe venous insufficiency, the situation is present a few hours after getting up in the morning.


Fingerprints can be seen in the swelling

If a light pressure is put on the ankle with your fingers, your fingerprints will mark your skin and the shape and form of your fingers will be seen on the skin.



This is more evident in people who are in an upright position over long periods in a day and it is even worse when it is hot.




Laying down stops the gravity effect

Once laying down, the gravity effect isn’t present anymore. The draining of the veins and the capillaries is easier.

The capillaries absorb the surplus once again. In the morning, the swelling (edema) of the ankles is pretty much resolve.



Deceiving treatment

The first step of a treatment is a change in habits, that is:

·        Try to keep the legs raised as much as possible when people are sitting;

·        Low salt food;

·        Diuretics, although often used, offer a disappointing result;

·        Graduated support stockings can help a lot, especially when the edema in the legs is painful. They must be put on in the morning, otherwise they will be difficult to put on your feet and calves later in the day.


Graduated pressure supportive stockings

The graduated pressure supportive stockings are expensive, uncomfortable and warm, especially in the summertime.

They can also be hard to put on; some people need assistance to put them on.



Other causes of venous congestion

Certain interventions in the veins in the legs may cause swollen legs as well.


Esthetic therapies for varicose veins

The same swelling problems can occur in patients who went through an esthetic intervention on varicose veins, once popular, but still possible nowadays.

The main vein at the bottom of the leg, the saphenous vein, is damaged by these treatments and becomes less or non-functional. Congestion occurs in the smaller blood vessels after the main one is damaged.


Using the veins in the legs for bypasses

Finally, we can see the same type of congestion described above (saphenous vein sclerosis) when a person has had a coronary bypass surgery.

The saphenous vein in one or both legs is cut and used to make the bypasses.

Edema in the legs in the patients will be asymmetric, but more present in the leg where the saphenous vein was taken.


Swelling of only one leg…

The other causes of edema located in the only one leg are usually related to another problem, not venous insufficiency.

If this is the case and in addition to this, redness or pain is associated to the swelling, consult a doctor as soon as possible.

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