Coagulation studies in preoperative neurosurgical patients

Unselected preoperative coagulation testing is known to have low positive y ield. However, no study has specifically evaluated neurosurgical patients. A retrospective study, of 1211 patients having neurosurgery over a one-year period was therefore conducted. Preoperative test results (activated parti al thromboplastin time [aPTT], prothrombin time [PT] and platelet count) an d historical factors indicating a potential bleeding tendency were recorded . Abnormality was defined as a test result outside the normal range for our laboratory. Seventeen per cent of all test results were abnormal. However if abnormality was redefined as a test result indicating potential bleeding tendency (low platelet count, prolonged aPTT and/or PT), only 7.2% of resu lts were abnormal. Many patients had factors on history indicating a potent ial bleeding tendency, but only a prolonged aPTT, cranial surgery and the u se of anti-hypertensive and anaesthetic drugs preoperatively predicted post operative bleeding. Prolonged aPTT was predictable on history in most patie nts. We conclude that routine screening of all preoperative neurosurgical p atients in our hospital is unnecessary.