[Isolated prolongation of the PTT: 2-year retrospective study].

The hemorrhagic risk associated with isolated prolongation of the PTT has been evaluated in a 2-year retrospective study. Of the 60 cases thus found, a hemorrhagic risk was present in 15 patients of whom 7 had hemophilia A, 5 von Willebrand's disease and 3 factor XI deficiency. Among the other etiologies not associated with a bleeding tendency, there were 31 proved or suspected cases with inhibitors of the PTT, most of whom were children, 2 factor XII deficiencies, 2 prekallikrein deficiencies and 4 contact phase activations. Isolated prolongation of the PTT is therefore without specificity and needs further investigation of hemostasis to determine the associated hemorrhagic risk.