Thromboelastometry (ROTEM) and thromboelastography (TEG) in copperhead snakebites: a case series.

Copperhead snakes account for approximately half of treated snakebites in the US, and bites can result in significant swelling, bruising and pain. While other pit vipers, such as rattlesnakes, frequently cause coagulopathy demonstrated by standard coagulation tests including international normalized ratio (INR), partial thromboplastin time (PTT), platelet count, and fibrinogen, copperheads do not appear to do so. Functional coagulation tests, such as rotational thromboelastometry (ROTEM) and thromboelastography (TEG) illustrate the clotting process and may detect coagulation defects that were not evident on standard tests. We reviewed a series of patients presenting with copperhead envenomation and compared coagulation parameters between those receiving standard coagulation tests and those receiving standard tests and ROTEM or TEG. Sixteen adults and children presented with copperhead snakebites, and four received ROTEM or TEG. None of the sixteen patients had abnormalities in PT, INR, PTT, platelets, or fibrinogen, and only one patient had an elevated D-dimer test. All four patients receiving ROTEM or TEG had normal values for ROTEM/TEG parameters and for standard coagulation tests. This corroborates previous research indicating that copperhead bites generally do not produce clinically significant coagulopathy. The role of thromboelastometry or thromboelastography in North American crotalid bites warrants further study.