Blood coagulation abnormalities associated with envenoming by Trimeresurus albolabris in Hong Kong

Abstract

Snake bites in Hong Kong are most commonly due to Tr. albolabris (White-lipped pit viper, bamboo snake). We studied 21 cases of envenoming by Tr. albolabris prospectively in order to document the incidence and severity of associated coagulation abnormalities. Eighteen patients (86%) had increased blood concentrations of fibrin degradation products (FDP) ranging from 10-40 micrograms/l to greater than 200 micrograms/l (normal: less than 10 micrograms/l), the majority of whom also had detectable soluble fibrin monomers. Among these 21 patients, 10 had decreased blood concentrations of fibrinogen ranging from 0.3 kg/l to 1.9 g/l (normal: 2-4 gl/l). In 11 cases (52%), the euglobulin clot lysis time was shortened (less than 150 minutes) in association with elevated blood concentrations of FDP (n = 10) and decreased circulating fibrinogen levels (n = 8). Thrombocytopenia and/or prolongation of prothrombin time (PT), activated partial thromboplastin time (APTT) and/or thrombin time (TT) were present in 10 patients (28%). Increased blood concentrations of FDP and decreased circulating fibrinogen levels were present in most of these cases. Envenoming by Tr. albolabris is therefore frequently associated with a coagulopathy compatible with increased fibrin/fibrinogenolysis. Measurement of blood concentrations of FDP is the most sensitive test for detecting the coagulopathy. There is, however, little correlation between the patterns of clinical manifestations and coagulation abnormalities although more severe clinical features were usually associated with high circulating FDP levels. Only one patient developed systemic bleeding but no fatality was observed. The coagulation abnormalities are usually correctable by replacement therapy. Further studies are required to study the mechanisms of this coagulopathy and its relationship with venom antigenaemia.