Ultrasound diagnosis and prognostic evaluation of free-floating thrombosis in popliteal vein

BO Ruting; DU Lilong; DAI Bing; YUAN Yu

doi:10.19300/j.2025.L20990

Abstract：Objective To analyze the ultrasound imaging characteristics of free-floating thrombosis(FFT)in the popliteal vein,follow up the recanalization after thrombolysis treatment,and to explore the relationship between ultrasound imaging characteristics and FFT prognosis.Methods A retrospective analysis was conducted on 48 patients with FFT in the popliteal vein caused by fractures around the knee joint,which were confirmed by digital subtraction angiography(DSA)or contrast-enhanced ultrasound.The FFT was diagnosed by the"sliding sign"on ultrasound,and the diagnostic accuracy of this sign for FFT was analyzed.Ultrasound follow-up was performed 1 week and l month after anticoagulant therapy to observe the recanalization of FFT in the popliteal vein,and patients were divided into the recanalization group(complete recanalization)and the thrombosis group(thrombus still existed).The chi-square test or Fisher's exact probability test was used to compare the echo,location,and floatability of FFT in the initial diagnosis of ultrasound between two groups.Results The diagnostic accuracy of the sliding sign for FFT was 100％.After 1 week of anticoagulant therapy,twenty-two patients(45.8％)were in the recanalization group and 26 patients(54.2％)were in the thrombosis group.The proportion of FFT with extremely low echo and high floatability on the initial diagnosis images in the recanalization group was higher than that in the thrombus group(all P＜0.05).After 1 month of anticoagulant therapy,there were 42 patients(87.5％)in the reperfusion group and 6 patients(12.5％)in the thrombosis group.The proportion of patients with FFT tail located in the distal segment of the popliteal vein on the initial diagnosis image in the recanalization group was higher than that in the thrombus group(P＜0.05).Conclusion Ultrasound is an effective diagnostic tool for identifying FFT.FFT exhibits extremely low echo,high floatability,and tail located in the distal segment of the popliteal vein,the patients have a more favorable prognosis.