Current evidence and guidelines suggest a time-based approach to the perioperative administration of direct oral anticoagulants (DOAC). Quantifying haematological concentrations of DOACs is possible however, the evidence suggests a large inter-individual variation and unlike INR is to warfarin, it does no correlation with anticoagulant effect. There are multiple confounding factors that affect DOAC metabolism and may result in a cohort of patients who satisfy one guideline (time based) but are ruled out using an objective, serum quantity-based guideline. The unsubstantiated use of DOAC level testing to inform surgical triage and use of reversal agents preoperatively may increase harm to patients.