Unpredicted late-, new-onset thrombocytopenia and hypofibrinogenemia in Fab antivenom-treated rattlesnake envenomation

Toxicon. 2020 Sep;184:55-56. doi: 10.1016/j.toxicon.2020.05.026. Epub 2020 Jun 4.


The use of Fab antivenom (Crotalidae Polyvalent Immune Fab (Ovine) (CroFab); Boston Scientific) against North American Crotalidae envenomation is associated with the development of late- (≥4 days post-envenomation), new-onset of hematological abnormalities. Although attempts have been made to identify predictive indicators during the acute phase of an envenomation, of patients who are not at-risk of late-, new-onset of hematological abnormalities, there has been at least one prior report of a patient who developed thrombocytopenia that was unpredicted by current indicators. We add three cases of unpredicted, late-, new-onset of hematological abnormalities in patients with Fab-treated rattlesnake bite.

Keywords: Antivenom; Envenomation; Fab; Fibrinogen; Platelets; Rattlesnake; Recurrence.

MeSH terms

  • Afibrinogenemia / chemically induced
  • Animals
  • Antivenins / therapeutic use*
  • Crotalid Venoms
  • Crotalus
  • Humans
  • Immunoglobulin Fab Fragments
  • Sheep
  • Snake Bites / complications
  • Snake Bites / drug therapy*
  • Thrombocytopenia / chemically induced*


  • Antivenins
  • Crotalid Venoms
  • Crotalidae Polyvalent immune Fab
  • Immunoglobulin Fab Fragments