An assessment of the utility of unselected coagulation screening in general hospital practice

Abstract

Coagulation screening using prothrombin time (PT) and activated partial thromboplastin time (APTT) is widely used. We performed an audit of coagulation screening in an Irish teaching hospital. We analysed PT and/or APTT results received during normal working hours during a 1-week period in our hospital. Abnormal results due to anticoagulants were excluded from further study. In samples with PT longer than 15.5 s and/or APTT longer than 42 s, we proceeded to 1: 1 mixing studies if the PT was prolonged and 1: 1 mixing studies, factor XII assay and lupus screen if the APTT was prolonged. We also obtained referral source for all samples and clinical details for abnormal samples. Six hundred and seventy-one coagulation requests were received during the study period. Three hundred and eighteen of 671 (47.4%) coagulation requests were for monitoring of anticoagulation. Three hundred and fifty-three of 671 (52.6%) requests were for coagulation screening rather than anticoagulant monitoring. In the coagulation screens received, PT was prolonged in 19 of 353 (5.4%). PT was longer than 20 s in four of 353 cases (1.1%). APTT was prolonged in 19 of 353 (5.4%). APTT was longer than 50 s in four of 353 (1.1%). No patients with abnormal PT or APTT had any bleeding sequelae during the study period. Unregulated coagulation screening has a low yield of abnormal results; the majority of these abnormal results show mild prolongation of PT or APTT with no evidence that they are associated with an increased bleeding risk.