Factors Associated with Systemic Bleeding in Envenomation in a Tertiary Hospital in the Brazilian Amazon.

snakebites usually present systemic bleeding, and the clinical⁻epidemiological and laboratorial factors associated with the development of this manifestation are not well established. In this study, we assessed the prevalence of snakebites with systemic bleeding reported at the , in Manaus, Amazonas State, Brazil, and the clinical⁻epidemiological and laboratorial factors associated with systemic bleeding. This is an observational, cross-sectional study carried out between August, 2013 and July, 2016. Patients who developed systemic bleeding on admission or during hospitalization were considered cases, and those with non-systemic bleeding were included in the control group. Systemic bleeding was observed in 63 (15.3%) of the 442 snakebites evaluated. snakebites mostly occurred in males (78.2%), in rural areas (89.0%) and in the age group of 11 to 30 years old (40.4%). It took most of the patients (59.8%) less than 3 h to receive medical assistance. Unclottable blood (AOR = 3.11 (95% CI = 1.53 to 6.31; = 0.002)) and thrombocytopenia (AOR = 4.52 (95% CI = 2.03 to 10.09; < 0.001)) on admission were independently associated with systemic bleeding during hospitalization. These hemostatic disorders on admission increase the chances of systemic bleeding during hospitalization. Prospective studies are needed to clarify the pathophysiology of systemic bleeding in snakebites in the Amazon region.