Widow Spider Envenomation Workup

Updated: May 28, 2020
  • Author: Sean P Bush, MD, FACEP; Chief Editor: Joe Alcock, MD, MS  more...
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Laboratory Studies

Laboratory tests should be obtained if the diagnosis is uncertain to exclude alternative diagnoses (eg, acute abdomen, myocardial infarction [16] ). The authors recommend the following, as appropriate:

  • Complete blood cell count
  • Cardiac markers (eg, troponin)
  • Pregnancy test when applicable
  • Comprehensive metabolic profile
  • Lipase
  • Urinalysis
  • Creatine kinase

Laboratory studies also may be necessary to evaluate for end-organ damage following widow spider envenomation.

It is common for the creatine kinase and peripheral white blood cell count to be elevated following widow spider envenomations.


Imaging Studies

Consider performing an acute abdominal series or an abdominal CT scan if the diagnosis is unclear in a patient presenting with abdominal pain.

Patients with focal neurologic deficits in the setting of severe hypertension following widow envenomation may require neuroimaging (eg, head CT).


Other Tests

Skin testing variably may predict immediate hypersensitivity to antivenom and may influence the decision regarding its administration. Antivenom-induced anaphylaxis may be more life-threatening than the envenomation itself.

Obtain an electrocardiogram in patients with comorbid conditions such as hypertension, coronary artery disease, and congestive heart failure, and in patients with chest pain or respiratory symptoms.