Low accuracy of microscopic hematuria in detecting coagulopathy from Bothrops pit viper bites, Brazilian Amazon.

Introduction: The common lancehead snakes (Bothrops atrox) are responsible for up to 90% of snakebites in the Amazon, especially in remote areas. The prevalence of microhematuria is similar to that of coagulopathy in B. atrox envenomation in the Amazon. Thus, this study aimed to assess the reliability of microhematuria as an inexpensive and simple alternative to detect snake-induced consumption coagulopathy. Methods: We analyzed samples from patients with confirmed B. atrox envenomation in terms of plasma fibrinogen and microhematuria (>3 red blood cells per high power field) in order to access the reliability of microhematuria to detect snakebite-induced coagulopathy, within 12 hours from admission. Results: A total of 186 patients were recruited. From the total, 85.5% of patients had hypofibrinogenemia and only about 50% (n = 94) had a microscopic examination of urine within 12 hours where microhematuria was present in 39 (41.5%). Diagnostic performance showed 38.6% sensitivity and 36.4% specificity (cutpoint 200 mg/dL). No clear association was seen between microhematuria and hypofibrinogenemia (r: -0.10; p: .34). Conclusion: In this study, microhematuria presented poor diagnostic performance to detect coagulopathy. Further studies are necessary to screen inexpensive and simple alternative diagnostic tools.

Evidence that Crotalus durissus terrificus (South American rattlesnake) envenomation in humans causes myolysis rather than hemolysis.

The venom of the South American rattlesnake Crotalus durissus terrificus was originally reported to have a pathophysiological activity mainly involving hemolysis and neurotoxicity. The systemic myotoxic action of this venom was demonstrated in 1985. In the present paper we report clinical and laboratory data concerning three patients bitten by C. durissus terrificus and treated at the University Hospital of Ribeirão Preto, University of São Paulo. The normal haptoglobin levels detected in the serum of these patients during the first 48 hr after the accident, as well as the absence of hemoglobin in darkened urine samples as evaluated by immunodiffusion against anti-hemoglobin serum, rule out the occurrence of intravascular hemolysis. These data permit us to conclude that the signs and symptoms observed in human envenomation with C. durissus terrificus are due to a myotoxic and neurotoxic action of the venom.