Case Definition: Long-Acting Anticoagulant (Super Warfarin)

Clinical description

After an acute unintentional ingestion of a long-acting anticoagulant, the majority of patients are entirely asymptomatic. After a substantial ingestion of a long-acting anticoagulant, clinical signs of coagulopathy typically occur within 24-72 hours. Coagulopathy might manifest as epistaxis, gingival bleeding, hematemesis, hematuria, hematochezia, menometrorrhagia, ecchymosis, petechial hemorrhages, intracranial hemorrhages, or bleeding that is disproportionate to the level of the injury (1-3).

Laboratory criteria for diagnosis

Biologic: The criteria for diagnosis of a long-acting anticoagulant is the presence of one of the following factors:

  • Prolonged prothrombin time (PT) and international normalized ratio (INR) (24 to 72 hours after exposure) persisting for weeks to months, as determined by hospital laboratory tests.
  • Abnormal assays for factors II and VII in patients with unexplained bleeding and a normal PT, partial thromboplastin time, or INR, as determined by hospital or commercial laboratory tests.
  • Detection of a long-acting anticoagulant (e.g., brodifacoum) in serum, plasma, or urine, as determined by commercial laboratory tests.

– OR –

  • Environmental: Detection of a long-acting anticoagulant in environmental samples.Case classification

Suspected: A case in which a potentially exposed person is being evaluated by health-care workers or public health officials for poisoning by a particular chemical agent, but no specific credible threat exists.

Probable: A clinically compatible case in which a high index of suspicion (credible threat or patient history regarding location and time) exists for a long-acting anticoagulant exposure, or an epidemiologic link exists between this case and a laboratory-confirmed case.

Confirmed: A clinically compatible case in which laboratory tests have confirmed exposure.

Additional resources

  1. Caravati EM, Erdman AR, Scharman EJ, et al. Long-acting anticoagulant rodenticide poisoning: an evidence-based consensus guideline for out-of-hospital management. Clin Toxicology 2007;45(1):1-22.
  2. Kruse JA, Carlson RW. Fatal rodenticide poisoning with brodifacoum. Ann Emerg Med 1992;21:331-6.
  3. Chua JD, Friedenberg WR. Superwarfarin poisoning. Arch Intern Med 1998;158:1929-32.
  4. NIOSH. NIOSH manual of analytical methods [online]. 2003. [cited 2013 Apr 5]. Available from URL:
  5. OSHA. Sampling and analytical methods [online]. 2010. [cited 2013 Apr 5]. Available from URL: icon.
  6. FDA. Food: Laboratory methods [online]. 2013. [cited 2013 Apr 5]. Available from URL: icon.
  7. EPA. Selected analytical methods: chemical methods query [online]. 2013. [cited 2013 Apr 5]. Available from URL: icon.
Page last reviewed: April 4, 2018