Key investigations

Key investigations for superwarfarin poisoning are:

• INR—measure in all patients who present following deliberate ingestions, and unintentional ingestions of more than 1 mg; repeat every 6 hours (initially) to define the extent of anticoagulation. The risk of serious bleeding based on the INR is the same as for warfarin poisoning—see Risk of serious bleeding from warfarin poisoning based on INR
• full blood count
• blood group and cross-match
• serum concentrations of the agent ingested (if available)—may help guide the duration of phytomenadione (vitamin K₁) therapy in patients who develop significant anticoagulation.