Simple screening method for deep vein thrombosis by duplex ultrasonography using patients' active maximum ankle dorsiflexion.

We hypothesized that venous obstruction by deep vein thrombosis (DVT) only slightly augments venous outflow from lower limbs by active ankle movements. If our hypothesis is true, we thought that we could develop a new screening method for DVT using duplex ultrasonography. Subjects were 22 lower limbs of 11 patients who gave informed consent for venography after total hip or knee arthroplasty. Around postoperative 19.0 days (range 15-32 days), we measured the ratios, called flow ratios, of the peak flow signal with active maximum ankle dorsiflexion and that at rest using duplex ultrasonography in the bilateral femoral veins. On the same day, we then performed bilateral venography. Thrombosis was detected in 5 of the 22 lower limbs. The mean flow ratios with and without DVT were 1.18 (range 1.0-1.3) and 3.31 (range 1.8-4.8), respectively. The flow ratios with DVT were significantly lower than those without DVT. Pain or difficulty performing active maximum ankle dorsiflexion was not observed in any of the operated or unoperated lower limbs during the ultrasound examination. In conclusion, ultrasonographic measurement of flow ratios may become a simple screening method for DVT in lower limbs without the pain or difficulty of performing active maximum ankle dorsiflexion.