Abstract

Background: Pulmonary embolism may develop due to unfavorable postearthquake living conditions and result in related deaths. Here we investigated the factors and characteristic ultrasonographic imaging 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 fromall participants, we retrospectively investigated the factors 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 ultrasonographic features as "the blowfish sign."

Conclusion: In middle-aged and elderly people, a higher prevalence of knee osteoarthritis was associated with FCMVT. FCMVT in the calf showed a characteristic finding termed as the blowfish sign.