Objective To explore the value of combining plasma D-dimer and bedside ultrasound examination for lower extremity deep venous thrombosis diagnosis.

Methods Sixty-nine patients with elevated plasma D-dimer in the intensive care unit received beside color Doppler ultrasound examination for lower limb venous in Xiamen Branch, Zhongshan Hospital, Fudan University from April 2018 to March 2019. The level of plasma D-dimer, and the result of the color Doppler ultrasound examination were recorded. The cutoff value of plasma D-dimer was calculated and the diagnostic efficiency of plasma D-dimer for lower limb deep venous thrombosis was analyzed retrospectively.

Results Thirty-nine non-thrombus cases and 30 thrombus cases were diagnosed by beside color Doppler ultrasound examination. There were 26 males and 13 females in the non-thrombus group, while 15 males and 15 females in the thrombus group. The average age was (63.7±13.8) years and (65.9±12.6) years, respectively. The level of plasma D-dimer were 3.26(0.91, 6.22) mg/L and 6.72(3.33, 13.24) mg/L (P < 0.05), respectively. The cutoff value of the level of plasma D-dimer was 4.54 mg/L, and the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were 66.7%, 69.2%, 60.6%, 72.2%, and 68.1%, respectively.

Conclusions The level of plasma D-dimer greater than 4.54 mg/L could be used as a meaningful bound value for clinical doctors to appoint bedside color Doppler ultrasound examination so as to reduce the waste of medical resources.