In pit viper envenomation, what coagulation abnormality may be observed?

In pit viper envenomation, what coagulation abnormality may be observed?

• A. Elevated INR and PTT
• B. Decreased INR only
• C. Normal coagulation tests
• D. Decreased PTT only

Answer: (A)

Pit viper venom often triggers a consumptive coagulopathy: it activates clotting pathways and uses up clotting factors, so both the extrinsic and intrinsic pathways can be affected. That leads to prolongation of coagulation tests that reflect those pathways, namely an elevated INR (which measures PT) and an elevated PTT (aPTT). In this venom-induced coagulopathy, you’re seeing the body's clotting factors being consumed, so times to clot are longer. Normal tests are less likely, and seeing a prolongation of only one test (INR or PTT) doesn’t fit the typical pattern.

Pit viper venom often triggers a consumptive coagulopathy: it activates clotting pathways and uses up clotting factors, so both the extrinsic and intrinsic pathways can be affected. That leads to prolongation of coagulation tests that reflect those pathways, namely an elevated INR (which measures PT) and an elevated PTT (aPTT). In this venom-induced coagulopathy, you’re seeing the body's clotting factors being consumed, so times to clot are longer. Normal tests are less likely, and seeing a prolongation of only one test (INR or PTT) doesn’t fit the typical pattern.