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Chronic Venous Insufficiency and Post-Thrombotic Syndrome


James D. Douketis

, MD, McMaster University

Reviewed/Revised Dec 2023
Topic Resources

Chronic venous insufficiency is damage to leg veins that prevents blood from flowing normally. Post-thrombotic syndrome is chronic venous insufficiency that results from a blood clot in the veins and causes symptoms.

The number of people in the United States who have chronic venous insufficiency is unknown. Different studies have given estimates of the number of people affected, and those estimates vary greatly. Post-thrombotic syndrome may develop in 20 to 50% of people with deep vein thrombosis Deep Vein Thrombosis (DVT) Deep vein thrombosis is the formation of blood clots (thrombi) in the deep veins, usually in the legs. Blood clots may form in veins if the vein is injured, a disorder causes the blood to clot... read more Deep Vein Thrombosis (DVT) , usually within 1 to 2 years.

Causes of Chronic Venous Insufficiency

Blood Vessels

Arteries carry blood with oxygen and nutrients away from the heart to the rest of the body. Veins return blood to the heart from the rest of the body. Blood returns from the legs through shallow and deep veins. Contraction of leg muscles pushes blood through the deep veins Deep Veins of the Legs Deep Veins of the Legs . Valves in the veins keep blood flowing upward toward the heart and stop the blood from flowing backward.

Chronic venous insufficiency occurs when something widens the leg veins and/or damages the valves in the veins. These changes decrease blood flow in the veins and increase the pressure in the veins. The increased pressure and low blood flow cause fluid to accumulate in the legs and other symptoms.

One-Way Valves in the Veins

One-way valves consist of two flaps (cusps or leaflets) with edges that meet. These valves help veins return blood to the heart. As blood moves toward the heart, it pushes the flaps open like a pair of one-way swinging doors (shown on the left). If gravity or muscle contractions momentarily pull the blood backward or if blood begins to back up in a vein, the flaps are immediately pushed closed, preventing backward flow (shown on the right).

One-Way Valves in the Veins

The most common cause of chronic venous insufficiency is

A blood clot may cause chronic venous insufficiency because scar tissue from the clot may damage the valves in the veins. Some people may then develop post-thrombotic syndrome, which is chronic venous insufficiency with symptoms.

Other risk factors for chronic venous insufficiency include

Post-thrombotic syndrome

Not everyone who has a blood clot in the leg develops post-thrombotic syndrome. People who are at increased risk following a blood clot in the leg include those who have had

  • Several episodes of blood clots in the same leg

  • A blood clot in the upper part of the leg and/or pelvic region

People who have obesity also may be at increased risk of post-thrombotic syndrome.

Symptoms of Chronic Venous Insufficiency

People with chronic venous insufficiency have leg swelling (edema Swelling Swelling is due to excess fluid in the tissues. The fluid is predominantly water. Swelling may be widespread or confined to a single limb or part of a limb. Swelling is often in the feet and... read more Swelling ), which typically is worse at the end of the day because blood must flow upward against gravity when a person is standing or sitting. Overnight, edema subsides because the veins empty well when people lie down. The swelling may not cause any symptoms, but some people feel fullness, heaviness, aching, cramps, pain, tiredness, and tingling in the legs.

Later on, the skin on the inside of the ankle becomes scaly and itchy and may become discolored. The discoloration is caused by red blood cells that escape from swollen (distended) veins into the skin. The discolored skin is vulnerable, and even a minor injury, such as that from scratching or a bump, can break it open, resulting in an ulcer. Ulcers may also develop without any known injury, typically on the inside of the ankle. Ulcers are usually only slightly uncomfortable. A very painful ulcer might be infected.

Examples of Skin Problems in Chronic Venous Insufficiency

If edema is severe and persistent, scar tissue develops and traps fluid in the tissues. As a result, the calf permanently enlarges and feels hard. In such cases, ulcers are more likely to develop, and they heal less easily.

Diagnosis of Chronic Venous Insufficiency

  • Doctor's evaluation

  • Sometimes ultrasonography

Doctors usually can diagnose chronic venous insufficiency based on its appearance and symptoms.

Treatment of Chronic Venous Insufficiency

Treatment involves

  • Leg elevation

  • Compression using properly applied bandages, graduated compression stockings, and/or intermittent pneumatic compression devices

  • Wound care

Elevating the leg above the level of the heart decreases pressure in the veins, and should be done for 30 minutes or longer at least 3 times per day.

Compression is effective and used for all people to help reduce swelling and discomfort. Elastic bandages are used first. Once edema decreases and ulcers begin to heal, people can use commercial graduated compression stockings. Such stockings are available with different amounts of pressure (highest pressure at ankles and lower pressures higher on the leg). Higher pressure stockings are more effective for severe problems but are more uncomfortable. Stockings should be put on when people awaken, before leg edema worsens with activity, and worn all day. Many people have difficulty using the stockings regularly. People may consider the stockings unattractive. More active people may consider stockings irritating or restricting. Some people may have difficulty putting them on.

Intermittent pneumatic compression (IPC) uses a pump to repeatedly inflate and deflate hollow plastic leggings. IPC squeezes blood and fluid out of the lower legs but is cumbersome. IPC therapy is used when compression stockings are not effective or the person in unable to tolerate them.

Wound care is important to heal leg ulcers. Various dressings have been developed that can be left under compression stockings for several days to a week. The Unna boot dressing uses zinc oxide–impregnated bandages. Other dressings provide a moist environment for wound healing and promote growth of new tissue.

Medications and surgery do not help chronic venous insufficiency, although skin grafting can be a last resort for skin ulcers that have not healed with other measures. However, the grafted skin will reulcerate unless the person consistently follows leg elevation and compression instructions.

Prevention of Chronic Venous Insufficiency

Losing weight, participating in regular exercise, and reducing the amount of sodium in the diet can help keep blood pressure in the leg veins low.

People who have had deep venous thrombosis should take anticoagulants Anticoagulant medications Deep vein thrombosis is the formation of blood clots (thrombi) in the deep veins, usually in the legs. Blood clots may form in veins if the vein is injured, a disorder causes the blood to clot... read more Anticoagulant medications to prevent post-thrombotic syndrome. Compression stockings do not prevent the development of chronic venous insufficiency but are useful for treatment.

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Aquaphor 3 IN 1 Diaper Rash, Aquaphor Baby Fast Relief Diaper Rash, Aquaphor Fast Relief Diaper Rash, Balmex, Boudreaux Butt Paste, Boudreauxs Rask, Carlesta, Coppertone, COZIMA, DermacinRx Zinctral, Desitin, Desitin Maximum Strength, Desitin Rapid Relief, Diaper Rash , Dr. Smith Adult Barrier, Dr. Smith's, Dr. Smith's Diaper Rash, Dr. Smith's Rash + Skin, DynaShield, Eucerin Baby Sunscreen Sensitive Mineral , Eucerin Sunscreen Sensitive Mineral, Flanders Buttocks , Medi-Paste, Novana Protect, PanOxyl AM, Triple Paste, Triple Paste Adult Incontinence, Z-Bum
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