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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 post exposure. Coagulopathy might manifest as epistaxis, gingival bleeding, hematemesis, hematuria, hematochezia, menometrorrhagia, ecchymosis, petechial hemorrhages, intracranial hemorrhages, or bleeding that is not in proportion with 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, as determined by FDA.

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. Corke PJ. Superwarfarin (brodifacoum) poisoning. Anaesth Intensive Care 1997;25:707-9.
  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.
  • Page last reviewed February 22, 2006
  • Page last updated March 04, 2005
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