“…The most pronounced changes postoperatively are found with respect to aPTT, which is normally prolonged after CPB both with and without residual heparinization 1,4,15 ; however, also fibrinogen, prothrombin time (PT ratio), and thrombin time (TT) are significantly altered after CPB. 1,4,15 Quite interestingly, changes outside the age-adjusted reference interval were observed for aPTT, PT, and TT in 40, 82, and 65% of children after surgery in one study, 1 whereas abnormalities in fibrinogen have been much more pronounced in other studies. 4,15 The predictive values (PV) of severe bleeding are comparable to those of viscoelastic tests, with positive-PV values ranging from 29 to 63% and negative-PV from 76 to 87%.…”