Page 64 - JSOM Summer 2020

APPENDIX A:
WHOLE BLOOD CLOTTING TEST (WBCT)
FOR VENOM-INDUCED CONSUMPTIVE COAGULOPATHIES (VICC)

The whole blood clotting test (WBCT) is a simple but critical WBCT testing should continue throughout the course of care to
bedside gross examination used in the assessment, diagnosis, and monitor for secondary resumption of venom-induced consumptive
therapeutic monitoring of snakebite patients in the developing coagulopathy. 1,70,114 After control of the envenomation has been
world and remote environments. 78,112–120 Refer to the diagram be- achieved, reassess WBCT every 24 hours throughout the course
low regarding instructions for performing the test. At minutes 20 of hospitalization. It is important to remember that the WBCT
and 30, the tube is gently picked up and tilted 90 degrees; a stable must be interpreted in the context of the larger clinical picture. If
solid clot retained within the tube is scored “Grade 0” and in- a patient has improved in all parameters except for a persistent
dicates normal coagulation. Abnormal results are scored “Grade abnormal WBCT, it may reflect an inertia in replenishment of de-
1” for a partial, semisolid clot that breaks apart and detaches pleted clotting factors after a severe hemotoxic envenomation. If
78
from the glass tube shortly after it is turned or “Grade 2” for the venom is active then hematocrit should continue to decrease or
completely incoagulable liquid blood that pours out of the tube signs of ongoing hemolysis or bleeding should be present.
immediately. Attempting to score the test earlier than 20 minutes
will not yield accurate results due to the consumptive mechanism
of the coagulopathy. Using a healthy donor as a control is ideal to
confirm questionable findings.

WHOLE BLOOD CLOTTING TEST (WBCT)
Draw 2 mL of venous blood and After exactly 20 minutes, pick up If clot breaks down quickly upon
transfer directly into a clean and dry the tube and invert it. If a solid clot inversion of the tube or fails to
glass tube. Leave it upright, openm is retained, the test indicates normal coagulate, the test indicates a
undisturbed for 20 and/or 30minutes coagulation. coagulopathy.
at root temperature.

Collection: a blood sample for WBCT Normal: a solid clot is retained upon Abnormal: clot degrades rapidly
testing immediately after collection. inversion of the tube at 20 or 30 (Grade 1, friable clot) or fails to
minutes (Grade 0, no coagulopathy). coagulate whatsoever (Grade 2).

62 | JSOM Volume 20, Edition 2 / Summer 2020