Delayed double reading of whole blood clotting test (WBCT) results at 20 and 30 minutes enhances diagnosis and treatment of viper envenomation

Abstract

BackgroundThe whole blood clotting test (WBCT) is a simple test of coagulation that is often used in the assessment, diagnosis, and therapeutic monitoring of snakebite patients in sub-Saharan Africa. WBCT requires only a clean glass tube and several milliliters of venous blood and is ideal for use in poorly equipped health centers throughout the rural areas where 95% of snakebites occur. However, questions surrounding the accuracy and reliability of the test remain unanswered due to variations in testing conditions and a lack of comparative research with which to validate them. This is the first study to evaluate WBCT results at both 20-min (WBCT20) and 30-min (WBCT30) reading times in the same group of snakebite patients.MethodsIn order to define the best reading time, the authors compared the results of serial WBCT evaluation at both 20 and 30 min after collection in 23 patients treated for snake envenomation in Bembèrèkè, northern Benin.ResultsWBCT results were identical at both reading times in patients without coagulopathy or when coagulation was restored permanently following a single dose of antivenom. Out of 17 patients with coagulopathy, 14 showed discrepancies between WBCT20 and WBCT30 results in at least one pair of serial evaluations. These could be completely contradictory results (e.g. normal clot at WBCT20 and no clot at WBCT30) or a marked difference in the quality of the clot (e.g. no clotting activity at WBCT20 and an unstable partial clot at WBCT30). WBCT discrepancies were encountered most frequently in three situations: initial normalization of hemostasis following antivenom therapy, detection of a secondary resumption of coagulopathy, or final restoration of hemostasis after a secondary resumption had occurred.ConclusionsThis study suggests that the WBCT is robust and that a sequential reading should improve the diagnosis and monitoring of venom-induced coagulopathies. It also indicates the possibility of discrepancies in the sensitivity of WBCT20 and WBCT30 for detecting the resolution or reoccurrence of coagulopathy and identifies how these findings, if confirmed, may be used to increase the efficacy and efficiency of antivenom treatment in the field.

Snakebite associated thrombotic microangiopathy: a systematic review of clinical features, outcomes, and evidence for interventions including plasmapheresis

“…Whole blood clotting times have limitations with respect to requirements for standardisation of glassware equipment and samples which can affect sensitivity and specificity in diagnosis of coagulopathy after snakebite. However, they remain in use globally as they are a simple bedside test available in resource limited settings [95][96][97]. Anaemia and thrombocytopenia were almost universally present, as seen in other TMAs such as HUS [98].…”

Hemorragia cerebral fatal después de una mordedura de serpiente Bothrops asper en la región del Catatumbo, Colombia

“…Una manera rápida, sencilla y eficaz para detectar el consumo de fibrinógeno es hacer la prueba de coagulación de sangre total a los 20 minutos (se puede complementar con la medición a los 30 minutos), la cual indica coagulopatía por consumo cuando no se forma coágulo en el tiempo estipulado (22,23). Esta prueba es útil en la valoración inicial del paciente con mordedura de serpiente en sitios en donde no se dispone de un laboratorio; se hace a la cabecera del paciente y su sensibilidad y especificidad son aceptables (23). Una prueba positiva significa que se han inoculado unos 300 mg de veneno.…”

Treatment of Chronic Venous Ulcers With Heterologous Fibrin Sealant: A Phase I/II Clinical Trial

“…To ascertain laboratory safety, particularly the possible AEs of the thrombin-like enzyme extracted from the venom of Crotalus durissus terrificus, the blood coagulation system of the participants was evaluated. According to the medical literature, envenomation caused by these snakes triggers important changes in blood coagulation through the consumption of coagulation factors, mainly fibrinogen and platelets (38)(39)(40)(41). In the present study, there were no significant alterations in the levels of platelets, fibrinogen, or the erythrocyte sedimentation rate (ESR) compared to the evaluations made before, during, and at the end of treatment.…”