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Fig. 1 | Journal of Venomous Animals and Toxins including Tropical Diseases

Fig. 1

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

Fig. 1

Collection and evaluation of the whole blood clotting test (WBCT). The WBCT20 should be taken from every suspected envenomation patient in Africa. The test must be performed in a clean dry, glass tube free of preservatives, soaps, or other contaminants – even plain vacutainers must be precleaned on site. A 10-mL glass test tube is well suited for this test. Measure out 2 mL into each tube, and when collecting from existing intravenous (IV) catheters perform a 2 mL waste draw to ensure collection of an undiluted sample. Assess at 20 and 30 min precisely. Partial clots and clots that rapidly degrade upon examination count as abnormal; this usually occurs within the first 5–30 sec after inversion of the tube. Solid clots that remain intact are considered normal. Test against blood from a healthy donor if results seem inconsistent with the clinical picture. The same tube may be used for both tests as long as it is not disturbed in between readings at 20 and 30 min. Note that the labeled vacutainer in the first two images was used to produce these photos for educational purposes and that vacutainers were not used for specimen collection during the study. The abnormal sample shown in the third picture was collected 3 h after antivenom administration in a patient suffering from an E. ocellatus envenomation during the study

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