Role of peripheral blood smear in identifying thrombotic microangiopathy in snakebites with venom-induced consumption coagulopathy.

Abstract

Introduction: Thrombotic microangiopathy is a clinical syndrome that may occur following snake envenomation, and is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and microvascular thrombotic occlusion, often leading to acute kidney injury. This study investigates the role of peripheral blood smear analysis in predicting thrombotic microangiopathy in snakebite patients with coagulopathy at a South Indian tertiary care center.

Methods: This prospective observational study was conducted over a 20-month period. Patients with snakebite-induced coagulopathy were enrolled, and those with a history of transfusion, bleeding disorders, hemolytic anemia, or anticoagulant use were excluded. Clinical assessments and laboratory investigations, including full blood count, peripheral blood smear, kidney function tests, and lactate dehydrogenase activity, were performed at 48 h, 72 h, and 96 h post-bite.

Results: Out of 58 patients, 9% developed thrombotic microangiopathy, with all cases showing fragmented red blood cells (schistocytes) on blood smear. Thrombocytopenia occurred in 43% of patients, and 36% developed acute kidney injury, with 16 requiring hemodialysis. Patients with schistocytes had longer hospital stays with a median of 30 days (IQR: 28-48 days) compared to those without schistocytes who had a median hospital stay of 7 days (IQR: 5-10 days) (P = 0.001). The mortality rate was 3%.

Discussion: The presence of schistocytes in peripheral blood smear was strongly associated with acute kidney injury and prolonged hospitalization. Schistocytes may serve as an early indicator of thrombotic microangiopathy in snakebite patients, facilitating timely intervention. The use of a peripheral blood smear is a simple, cost-effective diagnostic tool in resource-limited settings to aid in the prediction of thrombotic microangiopathy and guide treatment, especially for optimal referral to specialized centers.

Conclusions: Peripheral blood smear analysis can be a valuable predictor of thrombotic microangiopathy in snakebite patients, with a potential role in improving outcomes in resource-constrained settings that need further evaluation.