Bedside Coagulation Tests in Diagnosing Venom-Induced Consumption Coagulopathy in Snakebite

Abstract

Venom-induced consumption coagulopathy is the most important systemic effect of snake envenoming. Coagulation tests are helpful to accurately and promptly diagnose venom-induced consumption coagulopathy and administer antivenom, which is the only specific treatment available. However, bedside clotting tests play a major role in diagnosing coagulopathy in low-income settings, where the majority of snakebites occur. We conducted a literature search in MEDLINE® from 1946 to 30 November 2019, looking for research articles describing clinical studies on bedside coagulation tests in snakebite patients. Out of 442 articles identified, 147 articles describing bedside clotting assays were included in the review. Three main bedside clotting tests were identified, namely the Lee–White clotting test, 20-min whole blood clotting time and venous clotting time. Although the original Lee–White clotting test has never been validated for snake envenoming, a recently validated version has been used in some South American countries. The 20-min whole blood clotting time test is the most commonly used test in a wide range of settings and for taxonomically diverse snake species. Venous clotting time is almost exclusively used in Thailand. Many validation studies have methodological limitations, including small sample size, lack of case-authentication, the inclusion of a heterogeneous mix of snakebites and inappropriate uses of gold standard tests. The observation times for bedside clotting tests were arbitrary, without proper scientific justification. Future research needs to focus on improving the existing 20-min whole blood clotting test, and also on looking for alternative bedside coagulation tests which are cheap, reliable and quicker.

Malayan Pit Viper Envenomation and Treatment in Thailand

“…Additionally, VCT is subjected to methodological and analytical errors yielding false-positive results for hypofibrinogenemia caused by pit vipers. 15 Other methods with better sensitivity and specificity should be utilized to detect bleeding disorder in MPV envenomation such as 20minute WBCT and INR. 16 More appropriate diagnostic tools would also reduce inappropriate antivenin administration.…”

Clinical management of snakebite envenoming: Future perspectives

“…Given the challenges in diagnosis and known limitations of the 20WBCT, exploring alternative bedside tests, which are affordable, reliable, and quicker is a priority ( Wedasingha et al, 2020 ). At present, there is only one commonly available commercial diagnostic test available: Seqirus’ Snake Venom Detection Kit.…”

Snake Venoms in Diagnostic Hemostasis and Thrombosis

“…35,36 However, such coagulation studies are not necessarily widely accessible in low-income countries, where the majority of snakebites occur, and simple bedside methods are more commonly employed to detect VICC. 36 Tests such as the Lee-White clotting test, 20-minute whole blood clotting test, and venous clotting time are all variations on a theme of adding unanticoagulated whole blood to a glass test tube and assessing time to clot, or whether it clots at all. 36 Assessment of aPTT-based clot waveform analysis has been used to diagnose VICC in victims of Russell's viper venom envenomation, and has been shown to detect changes in coagulation before aPTT or whole blood clotting times became abnormal.…”

“…36 Tests such as the Lee-White clotting test, 20-minute whole blood clotting test, and venous clotting time are all variations on a theme of adding unanticoagulated whole blood to a glass test tube and assessing time to clot, or whether it clots at all. 36 Assessment of aPTT-based clot waveform analysis has been used to diagnose VICC in victims of Russell's viper venom envenomation, and has been shown to detect changes in coagulation before aPTT or whole blood clotting times became abnormal. 37 von Willebrand Factor Analysis Platelet adhesion to the subendothelial matrix is driven in vivo by shear stress, which induces a conformational change in von Willebrand factor (VWF), allowing it to bind to the platelet surface receptor glycoprotein Ib (GPIb).…”