Improved handling of the uremic haemolytic syndrome in renal failure brings forth the need to understand the extrarenal lesions (ERL). Few publications refer to them. Clinical data and autopsy material of 61 children dead with the uremic haemolytic syndrome (UHS) and less of 2 months of evolution were reviewed. 35 of them had ERL due to UHS with microthrombosis (MT). They were more frequent in those dying in the first 10 days of the acute stage: 27/34. Three of the 8 patients that had ERL after 10 days had repeated bouts of haemolisis and intravascular coagulation. Organs more frequently affected were: colon: 22 patients with MT, and also widespread necrosis in most of them; heart: 12 with MT and 5 of them with myocardial necrosis; brain: of 27 brains examined 9 had MT (mainly in the choroid plexuses), the others had edema, haemorrages, and spongiosis. Other organs with Mt were adrenals, pancreas, small bowel, etc.
We conclude that UHS is a generalized disease, and that ERL are frequent and important in the acute stage. They are responsable for many of the severe acute clinical signs, and they are also the inmediate cause of death in many patients or of severe sequelae in others.