• Presence at 1 year of a severe post-thrombotic syndrome clinically defined. [ Time Frame: 1 year ]
  

• Post-thrombotic syndrome at 2 years; [ Time Frame: 2 years ]
  
• Quality of life: CIVIQ Scale; [ Time Frame: inclusion, 1, 2 years before and after thermal cure ]
  
• Intensity of the symptoms of venous insufficiency auto evaluation by patient [ Time Frame: monthly ]
  
• Deep venous reflux (evaluated by echo-doppler); [ Time Frame: inclusion, 1 and 2 years ]
  
• Persistence of a residual thrombus (echo-doppler); [ Time Frame: inclusion, 1 and 2 years ]
  
• Correlation between clinical evolution and echo-doppler evolution of the venous after-effects; [ Time Frame: 1 year ]
  
• Benefit of a late cure at 2 years. [ Time Frame: 2 years ]
  

Venous thrombo-embolic disease (VTED) is a frequent pathology. The incidence is about 5 to 20 cases for 10000 persons each year, in a general population. The immediate risk is the pulmonary embolism potentially fatal. So, it justifies all the works in clinical research during the last years. Those studies allow many progresses, diagnostic and therapeutic, for the immediate undertaking of the patients. Despite that, VTED is a major problem of public health and the diminution of the mortality lied to VTED is one of the objectives of the French law relative to the politics of Public Health (August 2004). At more long-term, the post-thrombotic syndrome lead to an incapacitating pathology, which requires many cares. The frequency of the post-thrombotic syndrome is evaluated between 25 and 60% at middle-term (1 or 2 years). It depends of the studies and of the clinical primary end-points or vascular explorations. Rehabilitation has never been validated in this indication by studies with a correct methodology. Deep venous thrombosis (not in acute phase) is recognized as an indication for about 10 spa in France. But the specific or global benefit of this water cure is not clearly and scientifically proved. The importance of the venous pump of the calf and of the hydrostatic pressure in the physiopathology of the post-thrombotic syndrome make natural the use of balneotherapy for the prevention of this pathology for patients with severe deep venous thrombosis of lower limbs (proximal and obstruent). The venous thermal techniques have well-defined physiopathological targets. The haemodynamic and microcirculatory effects of some of them have been proved. The high degree of satisfaction of the patients that benefit from phlebological water cure every year in France indirectly shows the benefits that they feel. In those indications, prevention of the post-thrombotic syndrome is one of the well-recognize by the medical profession. For all that, there was not really validation of this indication with an acceptable methodology for the canons of the modern medicine. That is the reason why we undertake this randomized, single-blind controlled study with for main objective to demonstrate that hydrotherapy in a specific place can reduce the risk of post-thrombotic syndrome.