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Table 1 Grading system used to score WBCT results at both reading times

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

  Normal or abnormal? Visual appearance
Grade 0 Normal coagulation Stable, solid clot that maintains its shape and clings to the glass vessel without issues after rotation of the tube.
Grade 1 Abnormal, but there is some clotting activity apparent at the 20th and 30th minutes There is some blood in solid form, but it fails to adhere to the glass as a single plug and either disintegrates completely (friable clot) or partially degrades ≤30 sec after rotation.
Grade 2 Abnormal with no clotting activity apparent at the 20th and 30th minutes The entire blood sample remains in a free-flowing liquid state with no demonstrable clotting whatsoever upon rotation. This is immediately apparent during rotation of the tube.