Contributing Factors and Ultrasonographic Findings of Fresh and Chronic Mixed Venous Thrombosis in Post-Earthquake: A Cross-Sectional Study

Background: Pulmonary embolism may develop due to unfavorable postearthquake living conditions and result in related deaths. Here we investigated the factors and characteristic ultrasonographic imag-ing features associated with fresh and chronic mixed venous thrombosis (FCMVT) in the calf of middle-aged and elderly people after a major disaster.Methods: We included 791 individuals who underwent screening for deep venous thrombosis (DVT). After obtaining written informed consent from all participants, we retrospectively investigated the fac-tors contributing to FCMVT and characteristic findings of FCMVT in the calf based on interviews and ultrasonography results.Results: Patients with FCMVT were significantly older and had knee osteoarthritis significantly more frequently than patients with DVT and patients without thrombosis. Characteristic ultrasonographic images of FCMVT showed thrombi with mixed echogenicity. We referred to these characteristic ultra-sonographic features as "the blowfish sign."Conclusion: In middle-aged and elderly people, a higher prevalence of knee osteoarthritis was associ-ated with FCMVT. FCMVT in the calf showed a characteristic finding termed as the blowfish sign.