This article was produced and financed by The Research Council of Norway

Blood clots in the leg can lead to long-term damage, but an additional treatment reduces that risk. (Photo: Shutterstock)

Less blood clot damage with extra treatment

Roughly half the people who get a serious blood clot in the leg experience lasting damage. A little-used supplementary treatment can help prevent such complications.

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The Research Council of Norway

The Research Council of Norway is a government agency responsible for awarding grands for research as well as promoting research and science. It also advises the government in matters related to research.

Pain, swelling, itching, eczema and venous ulcers are characteristic signs of post-thrombotic syndrome, a condition developed by roughly half the patients who have experienced serious deep vein thrombosis, or blood clots in the leg.

In a study carried out in twenty Norwegian hospitals it has been demonstrated for the first time that a treatment to dissolve blood clots prevented such complications in a substantial number of patients. The treatment is called catheter-directed thrombolytic therapy.

No longer experimental

Catheter-directed thrombolytic therapy has been in modest use in Norway since the early 1990s and is known in other countries as well. But it is a costly treatment and until now its effect had not been documented.

Professor Per Morten Sandset (Photo: Birgit S. Kjelvik)

“In our study we have shown for the first time that this treatment truly can reduce the long-term complications of blood clots in the legs,” says project manager Per Morten Sandset, a professor at Oslo University Hospital’s Department of Haematology.

“This means it is no longer considered an experimental treatment and will likely be offered on a far larger scale.”

Dissolves blood clots

Roughly half of the study’s 209 blood-clot patients were randomly selected to receive standard treatment with blood-thinning medicine. The other half received thrombolysis in addition, administered via catheter and intended to dissolve blood clots.

Based at Oslo University Hospital, the project is a collaboration between the Department of Haematology and the Department of Radiology; all the hospitals in the South-Eastern Norway Health Region have participated. The study has received funding under the Research Programme on Clinical Research (KLINISKFORSKNING), administered by the Research Council of Norway.

The effects of the treatments were measured after six months and after two years, and will be measured again after five years. After two years, 41 percent of patients who received both thrombolysis and conventional therapy had developed post-thrombotic syndrome (PTS) compared to 55 per cent of patients receiving conventional therapy only.

Professor Sandset believes that refinements in the therapy will be able to substantially increase the rate of patients avoiding complications.

Open veins lower the risks

The study’s researchers observed a clear correlation between thrombolytic therapy, unobstructed veins and lower risk of developing PTS.

In thrombolytic therapy, patients receive medication through a catheter in the blood vessel and directly into the clot. This enables physicians to use a much lower dose than with conventional treatment, which is given intravenously.

The study also identified a drawback to thrombolytic therapy: increased risk of haemorrhaging. The researchers therefore recommend not using the treatment on patients at high risk for haemorrhage.


Read the article in Norwegian at

Translated by: Darren McKellep/Carol B. Eckmann

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