The Kimray-Greenfield filter: evaluation by duplex real-time/pulsed Doppler ultrasound

The Kimray-Greenfield filter is a wire cage which is inserted into the inferior vena cava (IVC) to prevent thrombi originating in pelvic and leg veins from embolizing to the lungs. Duplex real-time/pulsed Doppler ultrasound was used to evaluate placement and function in 38 patients (46 examinations). Real-time examination successfully identified the IVC and filter in 89% of cases. Pulsed Doppler studies demonstrated flow above and below the filter in 76%, accurately predicting normal flow in most cases. In 4 patients, Doppler scans revealed little or no flow distal to the filter; contrast cavograms confirmed obstruction secondary to thrombosis. This appears to be an accurate, noninvasive method of assessing postoperative reliability of the Kimray-Greenfield filter.