20WBCT
Definition
Twenty minute whole blood clotting test. A few millilitres of fresh venous blood are placed in a clean dry glass tube, left undisturbed for 20 minutes, and tilted. A normal clot indicates intact coagulation. A non-clotting sample is the bedside diagnosis of viperid envenomation.
- Full name
- 20-minute whole blood clotting test
- Sample
- Fresh venous blood in a clean, dry glass tube
- Procedure
- Left undisturbed 20 minutes, then tube tilted
- Diagnostic use
- Bedside screen for viperid envenomation
Common questions
Why must the tube be dry and left completely undisturbed?+
Contamination or agitation of the sample can artificially trigger or inhibit clotting, so a clean, dry, undisturbed tube ensures the observed clot forms solely from the blood's own coagulation status rather than an artefact of handling.
What does a non-clotting 20WBCT result mean clinically?+
It indicates a consumption coagulopathy consistent with viper envenomation, and can support a decision to start antivenom treatment at the bedside even before the snake species is confirmed.
Related terms
- Autonomic Storm
- The biphasic cardiovascular crisis of Indian red scorpion envenomation. An initial cholinergic phase of vomiting, salivation and bradycardia is followed by an...
- Neurotoxic Envenomation
- Venom-induced paralysis from blockade of the neuromuscular junction. The Indian cobra produces post-synaptic blockade through alpha-neurotoxins binding the acetylcholine receptor. The common...
- The Big Four
- The four Indian snake species responsible for the bulk of medically significant envenomation: Naja naja (Indian cobra), Bungarus caeruleus (common krait), Daboia...
- Venom ELISA
- An enzyme-linked immunosorbent assay in which species-specific anti-venom antibodies are used to detect residual venom antigen in serum, urine, bite-site exudate or...
- VICC
- Venom-induced consumption coagulopathy, the haemotoxic syndrome of Russell's viper and saw-scaled viper bites in which the venom activates coagulation factors, consumes fibrinogen...