Clinical outcomes of untreated symptomatic patients with negative findings on sonography of the thigh for deep vein thrombosis: Our experience and a review of the literature

OBJECTIVE. Our objective was to determine whether immediate venography or other additional imaging is necessary in symptomatic patients who have negative findings on sonography of the thigh for deep vein thrombosis (DVT). MATERIALS AND METHODS. We retrospectively evaluated the clinical outcomes of 146 patients with physical signs or symptoms consistent with DVT in whom sonography of the thigh was negative for DVT. We combined our results with those of three prospective studies that evaluated symptomatic patients with suspected DVT in whom sonography of the thigh had negative findings. Propagated DVT (from calf to thigh) and pulmonary emboli were considered adverse outcomes. RESULTS. Only one pulmonary embolus (0.7%) occurred in our patient population. However, one (7.7%) of 13 patients who underwent second examinations because of persistent symptoms developed thigh DVT. Review of the literature found four (0.2%) of 1797 patients subsequently developed pulmonary emboli after undergoing sonography of the thigh that was initially interpreted as having negative findings. Fifteen (12.5%) of 120 patients who underwent second sonographic examinations developed DVT of the thigh. No deaths from pulmonary emboli occurred in patients in our study or patients in the studies published in the medical literature. CONCLUSION. Immediate venography or other additional imaging is not necessary in symptomatic patients in whom sonography of the thigh is negative for DVT, given the exceedingly low risk of a pulmonary embolus. Follow-up sonography is indicated in persistently symptomatic patients to detect propagation of calf DVT into the thigh.