A Negative Venous Duplex Ultrasound Scan Alone Excludes Deep Venous Thrombosis in Clinical Practice

Abstract number: P1037

Gibbs H, Hetherington R, Gibb S, Catchpole I

Venous duplex ultrasound (VDU) is commonly the initial investigation for suspected deep venous thrombosis (DVT). VDU is often limited to a three site examination and the sensitivity of this has been reported to be too low to exclude DVT. We performed a prospective outcome study of a complete lower extremity VDU aiming to determine the incidence of clinical DVT developing after an initial negative VDU.

Methods:  All patients referred for VDU for suspected lower limb DVT during the twelve months to January 2004 were prospectively studied. All patients were in- or out-patients of a tertiary referral, teaching hospital. The deep veins of the lower extremity were examined throughout their length from the inguinal ligament to the ankle. DVT was diagnosed if venous incompressibility was present during transverse insonation.

Results:  614 patients underwent VDU for suspected acute lower extremity DVT during the study period. Of those, 436 patients had a negative VDU (224 males, 212 females; mean age 58.1 years). No other tests were performed to exclude DVT. Anti-coagulation (heparin, enoxaparin or warfarin) was subsequently administered to 40% of these patients, either for DVT prophylaxis, atrial fibrillation, prosthetic heart valves or vascular grafts. All patients were contacted by phone and underwent chart review to determine whether DVT or pulmonary embolism developed within three months of the initial VDU. Of the 436 patients with a negative VDU only 1 developed a DVT within the three month period. This patient was found to have DVT on repeat VDU 47 days later. The patient was hospitalized during this time with multiple medical conditions and had not received DVT prophylaxis due to epistaxis.

Conclusion:  A complete VDU examining all veins from the inguinal ligament to the ankle is effective at excluding DVT in clinical practice in a teaching hospital setting.