Preoperative history and coagulation screening in children undergoing tonsillectomy.

To evaluate the usefulness of preoperative screening for coagulation disorders in children, we prospectively studied laboratory and bleeding histories in 1603 children undergoing tonsillectomy. All patients had preoperative laboratory screening with a complete blood count, prothrombin time, activated partial thromboplastin time, and bleeding time. Persistent abnormalities on repeat testing 1 week later were investigated further by a standardized schema. A subset of 129 patients, including all those who bled perioperatively or had laboratory abnormalities, completed a standard historical questionnaire. Thirteen patients had persistent laboratory abnormalities diagnostic of lupus inhibitor (5), non-lupus inhibitor (6), mild hemophilia A (1), and vonWillebrand disease (1). Two patients had persistently prolonged activated partial thromboplastin times of undefined cause. Fourteen patients (10.8%) interviewed reported positive bleeding histories. Of these, five, including the patient with vonWillebrand disease, had persistent laboratory abnormalities. History alone failed to detect the patient with hemophilia A. For patients with inhibitors or prolonged activated partial thromboplastin times of unknown cause, surgery was delayed until the coagulation abnormalities resolved, and there was no perioperative bleeding. The patient with vonWillebrand disease had severe postoperative bleeding despite treatment with cryoprecipitate. In predicting perioperative bleeding, history and laboratory screening had a high specificity but a very low positive predictive value due to poor sensitivity and a low prevalence of bleeding. Some children with bleeding disorders may be identified first during routine preoperative coagulation testing, and replacement therapy or delay or cancellation of surgery may reduce or prevent perioperative hemorrhage. However, the large number of false positive laboratory tests and bleeding histories, coupled with the relative rarity of inherited and acquired coagulopathies, raises doubts about the overall value of routine screening.