Venom induced consumption coagulopathy and performance of 20-min whole blood clotting test for its detection in viperid envenomation

Abstract

Background: Venom induced consumption coagulopathy (VICC) and its underlying mechanisms have not been fully elucidated in viperid envenomation (VE), especially among Indian patients. We evaluated for VICC in VE, assessed the performance of 20-min whole blood clotting test (20WBCT) for VICC detection and also studied predictors of VICC. Methods: This hospital-based observational study enrolled 103 consecutive patients (age ⩾ 12 years) of snakebite admitted within 24 h of bite, with features of VE. They underwent 20WBCT, prothrombin time (PT)/international normalised ratio (INR), plasma fibrinogen and D-dimer testing during first 24 h after enrolment. Overt VICC (defined by overt bleeding), subclinical VICC (INR ⩾ 1.4 and/or fibrinogen < 2g/L, without overt bleeding), disseminated intravascular coagulation (DIC) (overt/non-overt, defined based on International Society on Thrombosis and Haemostasis (ISTH) DIC score) and primary defibrination (PDF) were evaluated among patients. Results: VICC overall was noted in 77 (≈75%) and overt VICC in 52 (≈50%). DIC (overt/non-overt) was noted in 59 (≈77%) and PDF in 2 (2.6%) patients with VICC. Sensitivity, specificity, positive predictive value and negative predictive value of 20WBCT for VICC detection were 98.7% (95%CI: 92.9–99.9%), 65.4% (95%CI: 44.3–82.8%), 89.4% (95%CI: 83.3–93.5%) and 94.4% (95%CI: 70.4–99.2%) respectively. Severe cellulitis in bitten limb predicted reduced VICC risk. Discussion: Majority (75%) of patients with VE had VICC and 68% with VICC had overt bleeding. DIC (overt/non-overt) was the predominant contributor to VICC. Though 20WBCT is a good screening test for VICC, false positive results should be kept in mind before deciding on snake antivenom treatment.