The long term sequelae of deep vein thrombosis.

Five hundred and sixty-four patients undergoing abdominal surgery, who were carefully assessed at the time of operation for evidence of venous thrombosis, have been followed up to determine the incidence of leg symptoms, varicose veins and post-thrombotic syndrome. Patients are frequently troubled by pain, swelling and phlebitis, which can persist for up to a year after operation. New varicose veins developed by 1 year in 20 per cent of patients. These occurred with increased frequency in patients who also developed a deep vein thrombosis, but they were also seen in patients who showed no clinical or isotopic evidence of thrombosis. The post-thrombotic syndrome was present in 26 patients by 3 years after the operation; half of these patients had suffered the syndrome before the definitive operation. Assessment of the long term effects of venous thrombosis must be carried out against the background of similar effects seen in patients without thrombi, and the development of the post-thrombotic syndrome may best be considered as the summation of a number of incidents, overt or occult, occurring throughout a lifetime.