The clinical impact of increased sensitivity PT and APTT coagulation assays

To determine how more-sensitive prothrombin time (PT) and activated partial thromboplastin time (aPTT) reagents affected the number and distribution o f abnormal test results and whether the increased sensitivity for deficienc ies resulted in improved diagnosis of clinically significant coagulopathies , we retrospectively compared preoperative coagulation screening data for 1 40 children undergoing open heart surgery after the reagent change with a s imilar group of 135 before the change. The more sensitive reagents resulted in a higher rate of abnormal values, but no increase in the identification of clinically significant hemostatic abnormalities. Of 67 patients with ab normal aPTTs in the group screened with more sensitive reagents, 63 had no further workup. No patients in either group were diagnosed subsequently wit h a coagulopathy because of unexpected bleeding. An abnormal test result di d not predict the need for perioperative blood products. We hypothesize tha t the high frequency of abnormal aPTTs bed to physician "desensitization" a bout the merit of coagulation screening. Therefore, we question the usefuln ess of preoperative coagulation screening of the pediatric cardiac surgery patient particularly since lasting changes in physician perception regardin g the clinical significance of abnormal values may lead to missed diagnoses in other settings.