Clinical outcomes of untreated symptomatic patients with negative findingson 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 o ther additional imaging is necessary in symptomatic patients who have negat ive findings on sonography of the thigh for deep vein thrombosis (DVT). MAT ERIALS AND METHODS. We retrospectively evaluated the clinical outcomes of 1 46 patients with physical signs or symptoms consistent with DVT in whom son ography of the thigh was negative for DVT. We combined our results with tho se of three prospective studies that evaluated symptomatic patients with su spected DVT in whom sonography of the thigh had negative findings. Propagat ed DVT (from calf to thigh) and pulmonary emboli were considered adverse ou tcomes. RESULTS. Only one pulmonary embolus (0.7%) occurred in our patient populati on. However, one (7.7%) of 13 patients who underwent second examinations be cause 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 sec ond sonographic examinations developed DVT of the thigh. No deaths from pul monary 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 necessa ry in symptomatic patients in whom sonography of the thigh is negative for DVT, given the exceedingly low risk of a pulmonary embolus. Follow-up sonog raphy is indicated in persistently symptomatic patients to detect propagati on of calf DVT into the thigh.