Patient Education Blog

DVT: Long-Term Damage – Post-Thrombotic Syndrome

While many people who have a DVT in a leg or arm recover completely, others can be left with some chronic symptoms: leg or arm swelling, pain, aching, heaviness, and cramping are some of the symptoms. These symptoms, in the case of a leg DVT, are typically worse after standing for a long time, and may be worse at the end of the day. They are improved in the morning or after elevating the limb. The pain and swelling can be disabling. The symptom complex is typically referred to as “Postthrombotic syndrome” (PTS) or “Postphlebitic syndrome”.


A number of other symptoms and finding may occur, and these are listed in Table 1. Dark pigmentation (image 1) may occur. It is due to the leakage of miniscule amounts of blood out of the veins into the soft tissues. Blood contains red cells (which are our oxygen carriers) and red cells contain iron. The iron from the red cells that leaked into the soft tissues is bound to a storage protein, and the complex is called hemosiderin, which is brown. The postthrombotic pigmentation may be unsightly; however, it does not cause symptoms and is not dangerous – it does not harm the skin.

If a person has significant chronic leg swelling, the skin may become hard, dry, and scaly (image 2).  If the chronic swelling is severe, skin breakdown may occur and an ulcer may form (venous stasis ulcer; image 3). Some people will develop what the physicians call “dermatoliposclerosis” (image 4): the tightness of the swollen leg leads to destruction of the skin and fat tissues. The person experiences this as hot, red, thickened, painful and tender areas of the skin, typically in the lower legs. This problem is not infrequently misdiagnosed as cellulitis (inflammation of the skin due to infection). If scar tissue forms in the skin without the development of ulcers, areas of white skin may arise.  This is referred to as “atrophie blanche” or “white atrophy (image 5).  Doctors may, subjectively, classify postthrombotic syndrome as mild, moderate or severe.  For clinical studies, more objective classification systems exist, the so-called Villalta and Ginsberg scales.

Who develops it?

An estimated 330,000 people in the United States have the postthrombotic syndrome. Typically, the more extensive the DVT, the more severe the symptoms of postthrombotic syndrome will be. However, this is not always so: even people who have had very extensive acute DVTs with severe symptoms may recover completely and may not be left with any chronic (long-term) symptoms. Approximately 60 % of patients will recover from a leg DVT without any residual symptoms, 40 % will have some degree of postthrombotic syndrome, and 4 % will have severe symptoms. The symptoms of postthrombotic syndrome usually occur within the first 6 months, but can occur up 2 years after the clot. If a patient has done well for ½ – 2 years after the clotting event, it is highly unlikely that he/she will develop the postthrombotic syndrome.

In people with arm DVT, postthrombotic syndrome develops in approximately 15 % of patients.  People with DVT of larger veins, i.e. those in the shoulder and upper chest area (in medial terms “axillary or subclavian vein thrombosis)” and people who still have left-over clot after the acute event (residual thrombosis) appear to be at particular risk for postthrombotic syndrome.

Little is known as to what predicts who will develop chronic symptoms and who will not. However, it is known, that people with DVT who wear daily compression stockings (see below) for several month after the acute DVT will develop significantly less postthrombotic syndrome.

What is it due to?

Normally, blood flows through veins out of the legs and arms back to the heart. Small valves in the veins enable the blood to flow in the right direction and prevent blood from flowing backwards and pooling in the veins of the legs and arms.  A clot (thrombosis) in the deep veins of legs or arms (deep vein thrombosis, DVT) leads to an obstruction of blood outflow from the extremities back to the heart. Acute leg swelling and pain, therefore, result. This is called an acute DVT. When the body tries to heal from these clots the valves in the veins are often damaged. The obstruction of the veins and the destruction of valves lead to impaired blood flow.

If a vein is completely blocked, neighboring smaller veins may enlarge to bypass the obstruction. These bypassing veins are called collaterals and can get quite large, particularly in the pelvis and abdomen in patients with thrombosis of the big vein in the abdomen (inferior vena cava). Such collaterals can sometimes be seen as prominent veins underneath the skin. If good collaterals have formed, symptoms of leg swelling and pain may not occur or may only be mild. However, in some people collaterals do not get very large and can, therefore, not carry all the blood needed to drain the legs or arms; this then leads to chronic leg or arm swelling, pressure and pain.

Several different terms are used for the chronic symptoms that can occur after a deep vein thrombosis: (a) postthrombotic syndrome, (b) postphlebitic syndrome, (c) venous insufficiency. These terms describe the same symptom complex. It is noteworthy that not all people who have these symptoms have had blood clots. Actually, the majority of people (88 %) have not had documented blood clots. The same symptoms occur in people with dysfunction of the valves in the veins, heart failure, obesity and other, often not clearly identifiable causes. The best, most accurate, and most widely used medical term for this condition is “venous stasis syndrome”. If one refers to venous stasis syndrome occurring after a DVT, an appropriate term is “postthrombotic syndrome”. “Lymphedema” also refers to swelling of one or both legs or arms and has the same symptoms and findings as post-thrombotic syndrome.  However, its causes are different: it is due obstruction of lymph vessels (and not the veins) that leads to a lack of drainage of fluid from the extremities, and, thus, to swelling.

Prevention and Treatment (Table 2)

Prevention is the key issue. If a person has leg swelling after an acute DVT, the person should wear a compression stocking to decrease the swelling. These should be custom fitted, i.e. a person’s leg should be measured to find a stocking that fits well. It needs to have a certain compression pressure, 35 mm Hg (mercury) at the ankle, 25 mm Hg at the mid-calf, and 18 mm Hg just below the knee. This is also sometimes called a “grade 2” stocking. If the leg swelling is below the knee, then a below-knee stocking is appropriate, but if swelling also involves the thigh, then an above-knee stocking should probably be worn. However, research on the benefit of compression stockings and prevention of the postthrombotic syndrome is ongoing. Sleeves (“gauntlets”) for postthrombotic syndrome in the arm also exist and should be worn if there is arm swelling or pain. Compression stockings and gauntlets can be purchased in medical supply stores and over the internet. It is preferrable that patient’s leg / arm sizes are individually fitted to  sure that the stockings / gauntlets fit right.  Also, knowledgeable personnel often has good suggestions/tricks how to get the tight stockings on more easily.

Unfortunately, compression stockings are often not worn because they are deemed unsightly or are uncomfortable. People should know that stockings come in various skin-tone and fashion colors, different shapes, sizes and materials, and from a variety of companies. It is worthwhile to make inquiries to find the right stocking that fits well, is relatively comfortable, and is acceptable in appearance. If stockings tend to roll down, you may want to choose a stocking that has a rubber strip at the upper end or you may want to wear a garter belt or compression pantyhose. Stockings should be worn during the day, while standing; stockings do not need to be worn at night. They should be worn for weeks, months, or years to control symptoms. For example, if swelling has disappeared a few weeks or months after the acute DVT with the use of the stockings, you may stop wearing the stocking. If swelling recurs then the stocking should be worn again. If there is no more swelling, then stockings are not needed any more.

So-called “Anti Embolism Stockings” or “TED hose” are often given to people who are hospitalized and have had surgery. They put mild pressure on the legs to prevent blood from clotting and can, to some degree, prevent blood clots in the legs (DVT). However, due to their low compression pressures they are NOT useful to prevent or treat the postthrombotic syndrome.

Elevation of the extremity above the level of the heart while resting or sleeping is also appropriate, if there is leg or arm swelling. Normalization of weight may also improve the symptoms. Moderate exercise immediately after the acute DVT (i.e. in the first 4 weeks) is not harmful. Physical exercise training and strengthening of the extremity muscles may improve the postthrombotic syndrome.  However, the role of physical exercise still needs to be investigated in clinical studies.  In cases of pronounced swelling that does not improve with compression stockings, a compression pump should be tried (see Table 3. Suppliers of Stockings and Pumps).  A battery-powered, transportable device is available (SCD EXPRESS by Tyco Healthcare), suitable for people who travel.

Pain management is important and needs to be individualized. Since many people with postthrombotic syndrome are on warfarin, pain medications that increase the risk for bleeding when taken regularly should not be used. Drugs that contain aspirin or the so-called non-steroidal anti-inflammatory drugs (NSAIDS), such as ibuprofen (Motrin®), naprosyn (Aleve®, Naproxen®, etc.) and others, should not be used.  Drugs that can be considered are (a) the non-narcotic drugs, such as acetaminophen (Tylenol®), Celebrex®, tramadol (Ultram®), and others, or (b) the narcotic drugs, such as acetaminophen with codeine or oxycodon (Tylenol® #2, 3 or 4, Tylox®, Percocet®, etc.), hydromorphone (Dilaudid®, etc.), fentanyl patch (Duragesic®), and others. Pain management can be complex and input from a specialized Pain Clinic may be helpful. Neurontin® (Gabapentin) is a pain modifier that has been used for so-called neuropathic pain associated with diabetic neuropathy and other pain syndromes. It has not been studied in the pain of postthrombotic syndrome, but could be tried for some time to see whether a person’s pain improves.

Sometimes, people with postthrombotic syndrome have a narrowing of one of the major veins in the pelvic area (iliac vein) or the abdomen (vena cava). This may be present from birth (called May-Thurner syndrome) or due to scarring of the blood vessel from a healed blood clot (stricture). If such a narrowing is present, it may be helpful to undergo a vascular radiology procedure during which the narrowing is ballooned open and can also be stented (see image: Balloon procedure and stenting). This should only be undertaken in a center that is experienced in doing these procedures.

Venous skin ulcers may be difficult to heal. Visits with a vein or wound care specialist may be helpful to get expert care. Elastic bandages (Unna boots: bandages that contain a combination of calamine lotion, glycerin, zinc oxide, and gelatin), or foam dressings (Profore™) often lead to wound healing. However, this is a slow process. Diligent wound care is necessary.

Psychological and social aspects:  The short and long-term impairment of physical functions may be frustrating, especially to people who were physically very active before their postthrombotic syndrome.  Oftentimes, such people will have to adjust their level of expectations, at least for the time being, and allow for their extremity function to slowly recover.  However, the impairment of extremity function may also lead to permanent inability to work in the previous occupation and the need for retraining or for disability application. A visit with a social worker to discuss these issues may be helpful.


  1. Kahn SR.  The postthrombotic syndrome. Am Soc Hemato Educ Program. 2010:216-220.
  2. Elman EE at al: The post-thrombotic syndrome after upper extremity deep venous thrombosis in adults: A systematic review. Thromb Res. In Press, Corrected Proof, Available online 6 July 2005.
  3. Villalta S et al: Assessment of validity and reproducability of a clinical scale for the post-thrombotic syndrome (abstract). Haemostasis 1994; 24(Suppl1):158a.
  4. Ginsberg JS et al: Postthrombotic syndrome after hip or knee arthroplasty: a cross-sectional study. Arch Intern Med 2000; 160:669-672.
  5. Heit JA et al: Trends in the incidence of venous stasis syndrome and venous ulcers: a 25 year population-based study. J Vasc Surg 2001;33:1022-1027.

Disclosure:  I have no financial conflict of interest relevant to this educational post.

Last updated:  July 20th, 2011

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11 Responses to “DVT: Long-Term Damage – Post-Thrombotic Syndrome”

  1. Bill says:

    Thank you so much for the blog. I have seen many doctors who thought the leg discoloration was a sun tan… I suffered from a DVT from my groin to the back of my knee and I have many of the symptom you described.

  2. natalie says:

    Thanks for this very informative post.

    Should mild PTS (no swelling or ulcers, but general achiness / cramping) after a very extensive DVT be managed by a primary care physician or a specialist? Who should prescribe the stockings?

    And is vein damage ever reversible? Conversely, if the vein is damaged, does it grow worse as one gets older? Or is the damage “done”?

    • Stephan Moll says:

      PTS can be managed and compression stockings prescribed by a primary care physician or a thrombosis specialist, as long as the MD prescribes the approrpiate ones (grade 2, individually fitted). Vein damage is typically not reversible. It has not been formally studied what happens with PTS after 2 years; however, it appears that, once a plateau of symptoms has been reached 1-2 years after the DVT, symptoms often stay the same and do not get worse. Weight loss, if the person is overweight, may lead to significant improvement in symptoms.

  3. Gail says:

    I really appreciate this well-written, thorough article. I have suffered with PTS since a misdiagnosed leg thrombosis 5 years ago. My physician advised me NOT to wear a compression stocking after the DVT. When I couldn’t stand it any longer, I went to a vascular specialist who told me I should wear it as much as possible during the day. I wear it everyday, even at the beach, which is completely embarrassing, but necessary. People are always asking questions when they see it, and it gives me an opportunity to educate them about DVT.

    • Stephan Moll says:

      As legs come short and long, spindle-shanked and chubby, it is better to have individually measured / fitted stockings, to make sure (a) they fit well, and (b) they supply the right pressure (30-40 mm Hg).

  4. Paul says:

    I had a severe blood clot to my left leg after an industrial accident tore the muscles in my leg and left me in an immobilizer. I am on warfarin daily and wear compression socks during the day. However i find as soon as i take the socks off at night, my left foot swells up, until the next morning when i put the compression socks back on and the swelling goes down. My vascular surgeon told me i will have this problem the rest of my life.

  5. SZia says:

    Hi, I had DVT (left leg) when I was pregnant with my second child. Was put on heparin and stockings and had a safe pregnancy and delivery. I continued with the heparin injections for 3 months post delivery and stockings for a year. Its 5 years now and I have been having issues with my arms – numbness in the hands, fingers, arm and shoulder pain and its worst when I wake up. I’ve seen a neuro, ortho, checked for rheumatism and even did a nerve test to check for carpal tunnel (I work long hours and use a computer) all tests came out clear. Is this PTS and is there any treatment for this?

    • Stephan Moll says:

      Postthrombotic syndrome (PTS) occurs in the extremity where the clot was. Thus, the history of leg DVT does not explain the arm symptoms. Could one postulate that the patient had an undiagnosed arm DVT at some point causing these arm symptoms now? Very unlikely, because: (a) It would be very unlikely to have such significant symptoms now without having had a clear episode of arm swelling in the past that would have suggested an arm DVT; (b) PTS symptoms are typically worse in the evening and lessened or gone in the morning; and (c) it would be unusual for numbness to be the predominant symptom. Could this be thoracic outlet syndrome or nerve irritation in the cervical spine? A good neurologist should be able to help with making a diagnosis.