Lower extremity venous sonography in the high-risk cancer population: one leg or two?

We correlated the diagnostic yield of unilateral and bilateral lower extremity venous sonograms in a high-risk cancer population with the clinical indication for the examination.

Reports from 433 bilateral and 619 unilateral lower extremity Doppler sonograms obtained over an 18-month period in patients with cancer were retrospectively reviewed, and clinical indication and findings were determined.

Overall, 228 (22%) of 1052 examinations revealed deep venous thrombosis (DVT): 83 (19%) of 433 bilateral and 145 (23%) of 619 unilateral. Among studies performed for unilateral symptoms (pain, edema, or postorthopedic procedure), 23% (135/581) of unilateral and 27% (44/162) of bilateral studies revealed DVT. Among these 44 bilateral studies with positive findings performed for unilateral symptoms, there were 30 DVT in the symptomatic side, 12 bilaterally, and two in the asymptomatic side alone. Ten percent (11/110) of the bilateral studies performed for bilateral symmetric symptoms revealed DVT. Among studies performed for bilateral asymmetric symptoms, 13% (1/8) of the unilateral and 8% (2/25) of the bilateral studies revealed DVT; both bilateral studies showed positive findings in the more symptomatic side. Among studies performed for suspected or proven pulmonary embolus, 20% (23/113) of bilateral and 54% (7/13) of unilateral studies had positive findings.

In a high-risk cancer population, the incidence of DVT in patients with unilateral symptoms is more than twice that of patients with bilateral symptoms. Because DVT isolated to an asymptomatic lower extremity is rare (1%), bilateral sonographic examination is generally unnecessary with unilateral lower extremity symptoms.