ASYMMETRY OF THE CALVES IN THE ASSESSMENT OF PATIENTS WITH SUSPECTED ACUTE PULMONARY-EMBOLISM

Purpose: The purpose of this investigation was to evaluate measured as ymmetry of the calves in the assessment of patients with suspected pul monary embolism (PE). Methods: Patients randomized for pulmonary angio graphy in the collaborative study of the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) were evaluated, Only patients in whom the circumference of the calves was measured were included in th is evaluation of PIOPED data, Among these, 232 had angiographically di agnosed PE and 446 had no PE by angiography. For purposes of compariso n, measurements of the calves also were made in a nonrandomized curren t cohort of 101 healthy subjects. All calf measurements were made 10 c m below the tibial tuberosity. Results: Asymmetry in the circumference of the calves of 1 cm or more was measured in 101 of 232 or 44% (95% confidence interval [CI], 37 to 51%) with PE, 176 of 446 or 39% (95% C I, 34 to 44%) without PE, and in 6 of 101 or 6% (95%, CI, 1 to 11%) co ntrol subjects (PE vs control subjects, p<0.001; subjects without PE v s control subjects, p<0.001; PE vs no PE, p=NS). Among patients with P E, the addition of calf asymmetry of 1 cm or more to qualitative signs of deep venous thrombosis increased the prevalence of a detectable ab normality of the lower extremities from 62 of 232 or 27% (95% CI, 21 t o 33%) to 129 of 232 or 56% (95% CI, 49 to 63% [p<0.001]). Conclusion: Asymmetry of the calves of 1 cm or more is abnormal, Such asymmetry o f the calves did not distinguish between patients with PE and those wi th no PE. When considered in proper perspective with other nonspecific signs and symptoms in patients with suspected acute PE, however, subt le calf asymmetry may call attention to the possibility of thromboembo lic disease. The observation of subtle asymmetry may indicate a need f or noninvasive diagnostic tests of the lower extremities to determine whether deep venous thrombosis is present.